Showing posts with label Blazor. Show all posts
Showing posts with label Blazor. Show all posts

Sunday, 15 February 2026

Blazor Property Grid - Updated version

Blazor Property Grid

I wrote a Blazor Property Grid component back in 2021, the updated the version is now available some five years later.

You will find the property grid available on Nuget here:

https://www.nuget.org/packages/BlazorPropertyGridComponents/1.2.4

The property grid allows inspection of an object's properties and also edit them. Supported data types are the fundamental data types, which means integers, date times, booleans, strings and numbers.

The property grid supports nested properties, properties that are compound objects themselves. I have not yet added template supported for custom data types, but fundamentals nested properties inside the complex property are shown. This means you can drill down into an object and both inspect the object and also edit the properties that are the mentioned fundamental data types.

This project delivers a Blazor property‑grid component capable of inspecting and editing both top‑level and deeply nested properties of an object. It works smoothly with nested structures and internal members.

It has been verified using Blazor WebAssembly running on .NET. 10. A sample client is included in the BlazorSampleClient project.

The component implementation is located inside the Razor Class Library BlazorPropertyGridComponents.

Licensing is MIT and the component is provided as‑is. If used in production, you are responsible for validating its suitability. Forks, modifications, and commercial reuse are allowed. The project originated as a personal learning exercise.

The screenshot below (from the sample client) illustrates the property grid on the right side updating the same model that the form on the left is bound to.

The component expects your project to include Bootstrap and Font Awesome. You can inspect exact versions inside libman.json. Additional styling resides in styles.css.

libman.json example

{
  "version": "1.0",
  "defaultProvider": "cdnjs",
  "libraries": [
    {
      "library": "bootstrap@5.3.3",
      "destination": "wwwroot/bootstrap/"
    },
    {
      "library": "font-awesome@6.5.1",
      "destination": "wwwroot/font-awesome/"
    }
  ]
}

Supported Property Types

  • DateTime (full or date‑only)
  • Float
  • Decimal
  • Int
  • Double
  • String
  • Bool
  • Enums (rendered using <select> and <option>)

Using the Component – API

Below is a Razor example showing how to use the component. The PropertySetValueCallback is optional and only required if you want UI changes reflected elsewhere immediately.

<div class="col-md-6"> <!-- Property grid shown in the right column -->
  <h4 class="mb-3">Property Grid Component Demo</h4>

  <PropertyGridComponent
      PropertySetValueCallback="OnPropertyValueSet"
      ObjectTitle="Property grid - Edit form for : 'Customer Details'"
      DataContext="@exampleModel">
  </PropertyGridComponent>
</div>

@code {
  private void OnPropertyValueSet(PropertyChangedInfoNotificationInfoPayload pi)
  {
    if (pi != null)
    {
      JsRunTime.InvokeVoidAsync(
        "updateEditableField",
        pi.FieldName,
        pi.FullPropertyPath,
        pi.Value
      );
    }
  }

  private CustomerModel exampleModel = new CustomerModel
  {
    Address = new AddressInfo
    {
      Zipcode = 7045,
      AddressDetails = new AddressInfoDetails
      {
        Box = "PO Box 123"
      }
    }
  };

  private void HandleValidSubmit()
  {
  }
}

The JavaScript function updateEditableField is located in script.js.

Updating via C# Instead of JS

You can also update the model directly through reflection. This approach ensures proper Blazor re‑rendering. Be sure to call StateHasChanged(). Note that this code is only required in case you use the property grid for editing properties and show the object you edit other places on the same page.

@code {

  private void OnPropertyValueSet(PropertyChangedInfoNotificationInfoPayload pi)
  {
    if (pi == null)
      return;

    SetPropertyByPath(exampleModel, pi.FullPropertyPath, pi.Value, pi.ValueType);
    StateHasChanged();
  }

  private void SetPropertyByPath(object target, string propertyPath, object value, string valueType)
  {
    if (target == null || string.IsNullOrEmpty(propertyPath))
      return;

    var parts = propertyPath.Split('.');
    var current = target;

    // Move to parent object

        // Navigate to the parent object
        for (int i = 0; i < parts.Length - 1; i++)
        {
            var prop = current.GetType().GetProperty(parts[i]);
            if (prop == null) return;
            current = prop.GetValue(current);
            if (current == null) return;
        }

        // Set the final property
        var finalProp = current.GetType().GetProperty(parts[^1]);
        if (finalProp == null) return;

        try
        {
            object convertedValue = value;

            if (finalProp.PropertyType.IsEnum && value != null)
            {
                var valStr = value.ToString();
                if (int.TryParse(valStr, out int intVal))
                    convertedValue = Enum.ToObject(finalProp.PropertyType, intVal);
                else
                    convertedValue = Enum.Parse(finalProp.PropertyType, valStr, ignoreCase: true);
            }
            else if (finalProp.PropertyType == typeof(bool) && value != null)
            {
                convertedValue = Convert.ToBoolean(value);
            }
            else if (value != null && finalProp.PropertyType != typeof(string))
            {
                convertedValue = Convert.ChangeType(value, finalProp.PropertyType);
            }

            finalProp.SetValue(current, convertedValue);
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Failed to set {propertyPath}: {ex.Message}");
        }
    }

    private CustomerModel exampleModel = new CustomerModel
    {
        Address = new AddressInfo
        {
            Zipcode = 7045,
            AddressDetails = new AddressInfoDetails
            {
                Box = "PO Box 123"
            }
        }
    };

    private void HandleValidSubmit()
    {

    }

}

I have used Claude Haiku 4.5 LLM to create a nice Architecture Documentation of my component so it is more convenient to see the structure of the Blazor property grid component. This is handy for those developers who wants to work on the component and add features and understood its structure. As mentioned before, the component is licensed with MIT license and you can adjust the component as needed free of use (and responsiblity).

πŸ”· Blazor Property Grid Component - Architecture Documentation


πŸ“Š Property Grid Component Structure

PROPERTY GRID COMPONENT ARCHITECTURE
====================================

ROOT CONTAINER: PropertyGridComponent.razor
├── EditForm (wraps the entire grid)
└── .property-grid-container
    ├── Header Table (.property-grid-header-table)
    │   └── thead (.property-grid-header)
    │       └── tr
    │           ├── th: "Property"
    │           ├── th: "Value"
    │           └── th: Edit Button (pencil icon)
    │
    └── Body Table (.property-grid-body-table)
        └── tbody (.property-grid-body)
            └── foreach KeyValuePair in Props
                ├── IF: Simple Property (IsClass = false)
                │   └── [COMMENTED OUT - NOT DISPLAYED]
                │
                └── IF: Nested Class (IsClass = true)
                    └── tr
                        ├── td (colspan=2)
                        │   ├── Expand/Collapse Button (minus icon)
                        │   └── div (.collapse .show)
                        │       └── PropertyRowComponent [Depth=1]
                        └── td (empty)


PROPERTY ROW COMPONENT: PropertyRowComponent.razor
====================================================

FOR EACH SubProperty in PropertyInfoAtLevel.SubProperties:
├── IF: Simple Type (not a class or System namespace)
│   └── tr (.property-row)
│       ├── td (.property-name-cell)
│       │   └── span (.property-name) = Property Name
│       │
│       └── td (.property-value-cell)
│           ├── IF: DateTime
│           │   └── InputDate (if editable) OR span (if readonly)
│           │
│           ├── IF: bool
│           │   └── InputCheckbox (if editable) OR span (if readonly)
│           │
│           ├── IF: int
│           │   └── InputNumber (if editable) OR span (if readonly)
│           │
│           ├── IF: double
│           │   └── InputText type="number" (if editable) OR span (if readonly)
│           │
│           ├── IF: decimal
│           │   └── InputText type="number" (if editable) OR span (if readonly)
│           │
│           ├── IF: float
│           │   └── InputText type="number" (if editable) OR span (if readonly)
│           │
│           ├── IF: string
│           │   └── InputText type="text" (if editable) OR span (if readonly)
│           │
│           ├── IF: Enum
│           │   └── select (if editable)
│           │       └── option foreach Enum value
│           │       OR span (if readonly)
│           │
│           └── ELSE: Unknown Type
│               └── span = Raw Value
│
└── IF: Nested Class (PropertyValue is HierarchicalPropertyInfo)
    └── tr (.property-row .nested-property-row)
        ├── td (colspan=2, .nested-property-cell)
        │   ├── span (.nested-property-name) = Nested Class Name
        │   ├── Expand/Collapse Button (plus icon)
        │   └── div (.collapse or .collapse.show)
        │       └── PropertyRowComponent [Depth+1] (RECURSIVE)
        └── [Empty td]


DATA STRUCTURE: HierarchicalPropertyInfo
================================================

HierarchicalPropertyInfo
├── PropertyName: string
├── PropertyValue: object
├── PropertyType: Type
├── SubProperties: Dictionary<string, HierarchicalPropertyInfo>
├── FullPropertyPath: string (dot-separated path)
├── IsClass: bool (indicates if this is a class type)
├── IsEditable: bool
├── NewValue: object (for tracking changes)
└── ValueSetCallback: EventCallback

HIERARCHY BUILD PROCESS:
========================

MapPropertiesOfDataContext(root object)
├── Create ROOT HierarchicalPropertyInfo
├── For each Public Property:
│   ├── IF: Simple Type (not class or not System namespace)
│   │   └── Add to SubProperties as leaf node (IsClass=false)
│   │
│   └── IF: Nested Class (class type, not System namespace)
│       └── Recursively call MapPropertiesOfDataContext
│           └── Add to SubProperties with nested tree (IsClass=true)
│
└── Return complete tree structure


INTERACTIVITY:
==============

Edit Mode Toggle:
├── ToggleEditButton() → IsEditingAllowed = !IsEditingAllowed
└── SetEditFlagRecursive() → walks entire tree setting IsEditable on all nodes

Value Changes:
├── SetValue() called on input change
├── Handles type conversion (enums, numbers, dates, etc.)
├── Updates PropertyValue immediately for UI reflection
└── Invokes ValueSetCallback → OnValueSetCallback()

Property Change Callback:
└── PropertySetValueCallback emits PropertyChangedInfoNotificationInfoPayload with:
    ├── FieldName
    ├── FullPropertyPath
    ├── Value
    └── ValueType (text, boolean, number, date, enum)

Expand/Collapse:
└── ToggleExpandButton() → JavaScript: blazorPropertyGrid.toggleExpandButton()
    └── Toggles Bootstrap collapse class on nested div

πŸ”§ Component Descriptions and Roles

1. PropertyGridComponent (PropertyGridComponent.razor + PropertyGridComponent.razor.cs)

Role: Root container and orchestrator for the entire property grid UI

Primary Responsibility:

Accepts a data object and transforms it into a hierarchical property structure

Key Functions:

  • OnParametersSet() - Initializes the component when parameters are passed
  • MapPropertiesOfDataContext() - Recursively walks the object graph and builds the HierarchicalPropertyInfo tree
  • IsNestedProperty() - Determines if a property should be expanded (nested classes)
  • ToggleEditButton() - Handles the edit mode button click (pencil icon in header)
  • SetEditFlag() / SetEditFlagRecursive() - Propagates the IsEditable flag through the entire tree
  • OnValueSetCallback() - Listens for value changes and emits PropertySetValueCallback events to the parent component

Parameters:

  • DataContext (object) - The root object to display
  • ObjectTitle (string) - Display title for the grid
  • IsEditingAllowed (bool) - Whether fields are editable
  • PropertySetValueCallback (EventCallback) - Callback when a property value changes

Rendering:

Header table with Property/Value columns and edit button. Body table containing rows for top-level properties (delegates nested properties to PropertyRowComponent)

2. PropertyRowComponent (PropertyRowComponent.razor + PropertyRowComponent.razor.cs)

Role: Recursive component that renders individual property rows and handles nested object expansion

Primary Responsibility:

Display a single level of properties and recursively display nested levels

Key Functions:

  • SetValue() - Handles input change events, performs type conversion, and invokes callbacks
  • ToggleExpandButton() - JS interop to toggle Bootstrap collapse classes for expand/collapse UI
  • Property type detection - Conditionally renders different input controls based on property type

Type Support:

  • DateTime → InputDate (HTML5 datetime-local)
  • bool → InputCheckbox
  • int → InputNumber
  • double, decimal, float → InputText with type="number"
  • string → InputText with type="text"
  • Enum → HTML select dropdown with enum values
  • Nested Classes → Recursive PropertyRowComponent call with Depth+1
  • Unknown Types → Raw span display

Parameters:

  • PropertyInfoAtLevel (HierarchicalPropertyInfo) - The current property node to render
  • Depth (int) - Nesting depth for styling and collapse behavior
  • DisplayedFullPropertyPaths (List<string>) - Tracks which paths have been rendered (prevents duplication)

Features:

  • Editable/Read-only modes based on IsEditable flag
  • Collapse/expand functionality for nested objects
  • Visual styling (beige background for read-only values)
  • Full property path as tooltip for clarity

3. HierarchicalPropertyInfo (HierarchicalPropertyInfo.cs)

Role: Data structure representing a single property node in the object hierarchy

Primary Responsibility:

Act as a node in a tree structure that mirrors the original object's property graph

Properties:

  • PropertyName (string) - Name of the property
  • PropertyValue (object) - Current value of the property
  • PropertyType (Type) - CLR type of the property
  • SubProperties (Dictionary<string, HierarchicalPropertyInfo>) - Child properties (for nested objects)
  • FullPropertyPath (string) - Dot-separated path from root (e.g., "Customer.Address.Street")
  • IsClass (bool) - Whether this represents a class type (true = nested object, false = leaf value)
  • IsEditable (bool) - Whether the property can be edited in the current UI state
  • NewValue (object) - Tracks modified value before submission
  • ValueSetCallback (EventCallback) - Callback when this property's value changes

4. PropertyChangedInfoNotificationInfoPayload (PropertyChangedInfoNotificationInfoPayload.cs)

Role: Payload object that carries change notification information back to the parent

Primary Responsibility:

Communicate property change events with detailed context

Properties:

  • FieldName (string) - Name of the property
  • FullPropertyPath (string) - Complete path to the property
  • Value (object) - New value
  • ValueType (string) - Type of value ("text", "number", "boolean", "date", "enum")

πŸ”„ Component Interaction Flow

User interacts with PropertyGrid
    ↓
PropertyGridComponent receives DataContext
    ↓
MapPropertiesOfDataContext() builds tree of HierarchicalPropertyInfo
    ↓
Renders PropertyRowComponent for each top-level property
    ↓
PropertyRowComponent renders based on type:
  ├─ Simple types → InputControl (text, number, checkbox, date, select)
  └─ Nested classes → Recursive PropertyRowComponent
    ↓
User edits a value
    ↓
PropertyRowComponent.SetValue() processes input
    ↓
ValueSetCallback invoked
    ↓
OnValueSetCallback() determines value type and emits PropertySetValueCallback
    ↓
Parent component receives PropertyChangedInfoNotificationInfoPayload

🎯 Key Design Patterns

1. Recursive Composition

PropertyRowComponent calls itself recursively for nested objects, allowing unlimited nesting depth.

2. Tree Structure

HierarchicalPropertyInfo forms a tree that mirrors the object graph, enabling efficient traversal and state management.

3. Event Cascading

Value changes propagate up through callbacks, maintaining separation of concerns between components.

4. Type-Driven Rendering

PropertyRowComponent dynamically renders different input controls based on CLR type, supporting datetime, enum, numeric, boolean, and string types.

5. Bootstrap Collapse Integration

Nested objects use Bootstrap's collapse classes for expand/collapse functionality, toggled via JavaScript interop.


πŸ“Š Data Flow Summary

DataContext (Object)
    ↓
MapPropertiesOfDataContext() [Reflection-based tree building]
    ↓
HierarchicalPropertyInfo Tree
    ↓
PropertyGridComponent → PropertyRowComponent Chain [Rendering]
    ↓
HTML Tables + Form Controls
    ↓
[User edits value]
    ↓
ValueSetCallback Events [Bubbling up]
    ↓
PropertyChangedInfoNotificationInfoPayload [Event payload]
    ↓
Parent Component [Handles business logic]

Sunday, 25 January 2026

Rendering Blazor components using HtmlRenderer

Rendering Blazor Components Dynamically with HtmlRenderer in .NET 8

πŸš€ Rendering Blazor Components Dynamically with HtmlRenderer in .NET 8

A practical example using a generic component renderer

Source code available here:
πŸ‘‰ https://github.com/toreaurstadboss/BlazorIntroCourse/tree/main/Components/Demos/TemplatedComponents

Blazor has always been about component‑driven UI, but until .NET 8, components were tightly coupled to the Blazor runtime — either WebAssembly or Server. With the introduction of HtmlRenderer, that boundary disappears.

You can now render any .razor component into pure HTML on the server, without a browser, without WebAssembly, and without a running Blazor app. This opens up a whole new world of scenarios:

  • Rendering components inside MVC, Razor Pages, or Minimal APIs
  • Generating HTML for emails, PDFs, reports, or static site generation
  • Using Blazor components as server‑side templates
  • Building dynamic component renderers that choose components at runtime
  • Running components in background services or unit tests

In this post, I’ll walk through a practical example: A generic Blazor component that uses HtmlRenderer to render any component dynamically, and a simple Bootstrap‑style Alert component to demonstrate how it works.


🎯 Why HtmlRenderer Matters

Here’s the short version — arguments you can inform other developers why HtmlRenderer opens up so many possibilities for using Blazor components many places:

  • Render Blazor components anywhere — MVC, Razor Pages, Minimal APIs, background jobs.
  • Generate static HTML — perfect for emails, PDFs, SEO, caching, and static sites.
  • Use Blazor components as templates — no need for Razor Views or TagHelpers.
  • Full component lifecycle — DI, parameters, cascading values, child content all work.
  • No browser required — everything runs server‑side.
  • Dynamic component composition — choose components at runtime using generics.
  • Great for testing — render components without a browser or JS runtime.

πŸ–Ό️ Diagram: How HtmlRenderer Works

Your Blazor Component (e.g., <Alert>) Generic Renderer (TComponent + parameters) HtmlRenderer .NET 8 server-side renderer HTML Output (string / MarkupString)

πŸ“¦Sample Blazor component used | Alert.razor — A Simple Bootstrap‑Style Alert Component


<div 
    class=@($"alert {(IsDismissable ? "alert-dismissible fade show" : "")} alert-{AlertType.ToString().ToLower()}")
    role="alert">
    @if (IsDismissable)
    {
        <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
    }
    @ChildContent
</div>

@code {

    [Parameter]
    public required RenderFragment ChildContent { get; set; } = @<b>Default message</b>;

    [Parameter]
    public bool IsDismissable { get; set; }

    [Parameter]
    public AlertTypeEnum AlertType { get; set; } = AlertTypeEnum.Success;

}


🧩 The alert type enum | AlertTypeEnum.cs


namespace DependencyInjectionDemo.Components.Demos.TemplatedComponents
{
    public enum AlertTypeEnum
    {
        Primary,
        Secondary,
        Success,
        Danger,
        Warning,
        Info,
        Light,
        Dark
    }
}


🧠 The Generic HTML Renderer Component | GenericHtmlRenderer.razor


@((MarkupString)RenderedHtml)

@typeparam TComponent

@code {
    [Parameter] public RenderFragment? ChildContent { get; set; }
    [Parameter] public Dictionary<string, object?> Parameters { get; set; } = new();

    [Inject] IServiceProvider ServiceProvider { get; set; } = default!;
    [Inject] ILoggerFactory LoggerFactory { get; set; } = default!;

    private string RenderedHtml { get; set; } = string.Empty;

    protected override async Task OnInitializedAsync()
    {
        if (ChildContent != null)
        {
            Parameters["ChildContent"] = ChildContent;
        }

        RenderedHtml = await RenderComponentAsync(Parameters);
    }

    private async Task<string> RenderComponentAsync(Dictionary<string, object?> parameters)
    {
        if (!typeof(IComponent).IsAssignableFrom(typeof(TComponent)))
        {
            throw new InvalidOperationException($"{typeof(TComponent).Name} is not a valid Blazor component.");
        }

        using var htmlRenderer = new HtmlRenderer(ServiceProvider, LoggerFactory);
        var parameterView = ParameterView.FromDictionary(parameters);

        var html = await htmlRenderer.Dispatcher.InvokeAsync(async () =>
        {
            var result = await htmlRenderer.RenderComponentAsync(typeof(TComponent), parameterView);
            return result.ToHtmlString();
        });

        return html;
    }
}

Note that we must also check if the parameters sent in here actually are present in the component. That means the parameter is a public property with attribute Parameter. The revised code of the method RenderComponentAsync is shown below.

private async Task<string> RenderComponentAsync(Dictionary<string, object?> parameters)
{

    if (!typeof(IComponent).IsAssignableFrom(typeof(TComponent)))
    {
        throw new InvalidOperationException($"{typeof(TComponent).Name} is not a valid Blazor component.");
    }

    using var htmlRenderer = new HtmlRenderer(ServiceProvider, LoggerFactory);

    var filteredParameters = GetValidParameters(parameters);

    var parameterView = ParameterView.FromDictionary(filteredParameters);

    var html = await htmlRenderer.Dispatcher.InvokeAsync(async () =>
    {
        var result = await htmlRenderer.RenderComponentAsync(typeof(TComponent), parameterView);
        return result.ToHtmlString();
    });

    return html;
}

private Dictionary<string, object?> GetValidParameters(Dictionary<string, object?> parameters)
{
    var validnames = typeof(TComponent).GetProperties(BindingFlags.Public | BindingFlags.Instance)
        .Where(p => p.IsDefined(typeof(ParameterAttribute), true))
        .Select(p => p.Name)
        .ToHashSet(StringComparer.OrdinalIgnoreCase);   
    validnames.Add("ChildContent");

    var filteredParameters = parameters
        .Where(kvp => validnames.Contains(kvp.Key))
        .ToDictionary(kvp => kvp.Key, kvp => kvp.Value);

    var unknownKeys = parameters.Keys.Except(filteredParameters.Keys, StringComparer.OrdinalIgnoreCase).ToList();
    if (unknownKeys.Count > 0)
    {
        var logger = LoggerFactory.CreateLogger("GenericHtmlRenderer");
        string warningmsg = $"Dropped unknown component parameters for {typeof(TComponent).FullName}: {string.Join(",", unknownKeys)}";
        logger.LogWarning(warningmsg);
        Console.WriteLine(warningmsg);
    }

    return filteredParameters;
}

This adjustment makes the code more resilient in case a non-existent parameter is sent in. Please note that an invalid parameter value will still give a runtime exception, so further validation could be added here, such as using TypeConverter to check if we can convert the parameter value sent in to the parameter in the component. The revised code is shown below.

@using System.Reflection
@using System.ComponentModel
@using Microsoft.AspNetCore.Components
@((MarkupString)RenderedHtml)

@typeparam TComponent

@code {
    [Parameter] public RenderFragment? ChildContent { get; set; }
    [Parameter] public Dictionary<string, object?> Parameters { get; set; } = new();

    [Inject] IServiceProvider ServiceProvider { get; set; } = default!;
    [Inject] ILoggerFactory LoggerFactory { get; set; } = default!;

    private string RenderedHtml { get; set; } = string.Empty;

    protected override async Task OnInitializedAsync()
    {
        if (ChildContent != null)
        {
            Parameters["ChildContent"] = ChildContent;
        }

        RenderedHtml = await RenderComponentAsync(Parameters);
    }

    private async Task<string> RenderComponentAsync(Dictionary<string, object?> parameters)
    {

        if (!typeof(Microsoft.AspNetCore.Components.IComponent).IsAssignableFrom(typeof(TComponent)))
        {
            throw new InvalidOperationException($"{typeof(TComponent).Name} is not a valid Blazor component.");
        }

        using var htmlRenderer = new HtmlRenderer(ServiceProvider, LoggerFactory);

        var filteredParameters = GetValidParameters(parameters);

        var parameterView = ParameterView.FromDictionary(filteredParameters);

        var html = await htmlRenderer.Dispatcher.InvokeAsync(async () =>
        {
            var result = await htmlRenderer.RenderComponentAsync(typeof(TComponent), parameterView);
            return result.ToHtmlString();
        });

        return html;
    }


    private Dictionary<string, object?> GetValidParameters(Dictionary<string, object?> parameters)
    {
        var componentType = typeof(TComponent);

        // Get valid property names and their PropertyInfo
        var validProperties = componentType.GetProperties(BindingFlags.Public | BindingFlags.Instance)
            .Where(p => p.IsDefined(typeof(ParameterAttribute), true))
            .ToDictionary(p => p.Name, p => p, StringComparer.OrdinalIgnoreCase);

        // Add ChildContent as a special case
        validProperties["ChildContent"] = null!;

        var filteredParameters = new Dictionary<string, object?>(StringComparer.OrdinalIgnoreCase);

        foreach (var kvp in parameters)
        {
            if (validProperties.ContainsKey(kvp.Key))
            {
                var propertyInfo = validProperties[kvp.Key];

                if (propertyInfo != null)
                {
                    var targetType = propertyInfo.PropertyType;
                    var value = kvp.Value;

                    // Check if value is null or already assignable
                    if (value == null || targetType.IsInstanceOfType(value))
                    {
                        filteredParameters[kvp.Key] = value;
                    }
                    else
                    {
                        // Use TypeDescriptor to check conversion
                        var converter = TypeDescriptor.GetConverter(targetType);
                        if (converter != null && converter.CanConvertFrom(value.GetType()))
                        {
                            try
                            {
                                filteredParameters[kvp.Key] = converter.ConvertFrom(value);
                            }
                            catch
                            {
                                LogConversionWarning(kvp.Key, value);
                            }
                        }
                        else
                        {
                            LogConversionWarning(kvp.Key, value);
                        }
                    }



πŸ§ͺ Demo Page — Rendering Alerts Dynamically | GenericHtmlRendererDemo.razor


@page "/GenericHtmlRendererDemo"
@using BlazorIntroCourse.Components.Demos.TemplatedComponents

<h3>GenericHtmlRendererDemo - Dynamic Alert rendering</h3>

<h6>Here the parameters are set in code</h6>
<GenericHtmlRenderer TComponent="Alert"
                     ChildContent="alertContent"
                     Parameters="alternateAlertParameters" />

<h6>Here we use the ChildContent element to enter in the html</h6>
<GenericHtmlRenderer TComponent="Alert"
                     Parameters="alertParameters">
    <ChildContent>
        <text>This is the second alert</text>
    </ChildContent>                 
</GenericHtmlRenderer>

<h6>Here we use inline object initializer for parameters</h6>
<GenericHtmlRenderer TComponent="Alert"
                     Parameters="@(new Dictionary<string, object>{
    [ "AlertType" ] = AlertTypeEnum.Danger,
    [ "IsDismissable" ] = true
})">
    <ChildContent>
        <text>This is the third alert</text>
    </ChildContent>  
</GenericHtmlRenderer>

@code {

    private RenderFragment alertContent = @<text>This is the first Alert</text>;
    Dictionary<string, object?> alertParameters = new()
    {
        { "AlertType", AlertTypeEnum.Info}, 
        { "IsDismissable", true }
    };

    Dictionary<string, object?> alternateAlertParameters = new()
    {
        { "AlertType", AlertTypeEnum.Success }, 
        { "IsDismissable", true }
    };

}


πŸ“˜ Diagram: Where You Can Use HtmlRenderer

HtmlRenderer API .NET 8 MVC Razor Pages Minimal APIs Background Jobs (emails, PDFs, reports) Static HTML Generation

🏁 Wrapping Up

HtmlRenderer in .NET 8 is one of those features that quietly unlocks a huge amount of flexibility. It turns Blazor components into universal UI building blocks that can be rendered:

  • in a browser
  • on the server
  • inside MVC
  • inside Razor Pages
  • inside Minimal APIs
  • inside background services
  • inside unit tests
  • or even at build time

The generic component renderer shown here is a concrete example of how powerful this can be — dynamic component rendering, runtime composition, and server‑side HTML generation all in one.

If you’re curious, you can explore the full source code here: (part of a larger repo I am looking into currently as a playground for misc Blazor functionality):
πŸ‘‰ https://github.com/toreaurstadboss/BlazorIntroCourse/tree/main/Components/Demos/TemplatedComponents

Sunday, 6 July 2025

Blazorise Datepicker with highlighting of dates

The Blazorise Datepicker is a date picker control for setting dates in Blazor WASM web assembly apps. It uses Flatpickr to provide a user friendly UI for selecting a date and navigate among months and years. It is used in web apps that use Blazor. The date picker is documented here :
https://blazorise.com/docs/components/date-picker
This date picker does not support highlighting certain dates. It do support enabling specified dates or disabling specified dates. But highlighting dates is not possible. I have added a Github repo where this is added support for :

https://github.com/toreaurstadboss/BlazoriseDatePickerWithHolidays

First off, the following custom Blazor component provides the custom date picker with the support for highlighting specified dates.

CustomDatePicker.razor




@using Blazorise
@using Blazorise.Localization
@using BlazoriseDatePickerWithHolidays.Service
@using System.Globalization
@using static BlazoriseDatePickerWithHolidays.Service.HolidayService
@inject IJSRuntime JS
@inject ITextLocalizerService TextLocalizerService

<Addons>
    <Addon AddonType="AddonType.Body">
        <DatePicker TValue="DateTime"
                    Date="@SelectedDate"
                    FirstDayOfWeek="@FirstDayOfWeek"
                    DateChanged="@OnDateChanged"
                    InputFormat="@InputFormat"   
                    InputMode="@InputMode"
                    DisplayFormat="@DisplayFormat"                    
                    Placeholder="@Placeholder"
                    TimeAs24hr="@TimeAs24hr"
                    @attributes="@AdditionalAttributes"
                    @ref="datePicker" />
    </Addon>
    <Addon AddonType="AddonType.End">
        <Button Class="addon-margin" Color="Color.Primary" Clicked="@(() => datePicker?.ToggleAsync())">
            <Icon Name="IconName.CalendarDay" />
        </Button>
    </Addon>
</Addons>

@code {
    /// <summary>
    /// List of dates to be highlighted in the date picker. Each date can have an annotation (e.g., holiday name) that will be shown as a tooltip.
    /// </summary>
    [Parameter]
    [EditorRequired]
    public List<AnnotatedDateTime> HighlightedDays { get; set; }

    /// <summary>
    /// The CSS class to apply to highlighted dates in the calendar.
    /// </summary>
    [Parameter]
    public string HighlightCssClass { get; set; } = "pink-day"; //Default CSS class pink-day is a custom CSS class defined in wwwroot/css/app.css

    /// <summary>
    /// The first day of the week in the date picker calendar. Defaults to Monday.
    /// </summary>
    [Parameter]
    public DayOfWeek FirstDayOfWeek { get; set; } = DayOfWeek.Monday;

    /// <summary>
    /// Whether to display time in 24-hour format. Defaults to true.
    /// </summary>
    [Parameter]
    public bool TimeAs24hr { get; set; } = true;

    /// <summary>   
    /// The locale to use for the date picker, which affects date formatting and localization. 
    /// Supported locales : https://blazorise.com/docs/helpers/localization
    /// </summary>
    [Parameter]
    public string Locale { get; set; } = "en-US";

    /// <summary>
    /// The input mode for the date picker, which can be either Date or DateTime or Month.
    /// </summary>
    [Parameter]
    public DateInputMode InputMode { get; set; } = DateInputMode.Date;

    /// <summary>
    /// The currently selected date in the date picker.
    /// </summary>
    [Parameter] 
    public DateTime SelectedDate { get; set; }

    /// <summary>
    /// Event callback triggered when the selected date changes.
    /// </summary>
    [Parameter] 
    public EventCallback<DateTime> SelectedDateChanged { get; set; }

    /// <summary>
    /// The input format string for displaying the date in the input field.
    /// </summary>
    [Parameter] 
    public string? InputFormat { get; set; } = "dd.MM.yyyy";

    /// <summary>
    /// The display format string for showing the date in the calendar.
    /// </summary>
    [Parameter] 
    public string? DisplayFormat { get; set; } = "dd.MM.yyyy";

    /// <summary>
    /// Placeholder text to display when no date is selected.
    /// </summary>
    [Parameter] 
    public string? Placeholder { get; set; }

    /// <summary>
    /// Whether to show the clear button in the date picker.
    /// </summary>
    [Parameter] 
    public bool ShowClearButton { get; set; } = true;

    /// <summary>
    /// Additional attributes to be splatted onto the underlying DatePicker component.
    /// </summary>
    [Parameter(CaptureUnmatchedValues = true)] 
    public Dictionary<string, object>? AdditionalAttributes { get; set; }

    /// <summary>
    /// Handles component rendering and registers JS interop for month and year changes.
    /// </summary>
    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            _dotNetRef = DotNetObjectReference.Create(this);
            await JS.InvokeVoidAsync("registerFlatpickrMonthChange", "input.flatpickr-input", _dotNetRef);
            await JS.InvokeVoidAsync("registerFlatpickrYearChange", "input.flatpickr-input", _dotNetRef);
        }
        await ReloadDatesToHighlight();
    }

    protected override void OnParametersSet()
    {
        if (Locale != null){
            TextLocalizerService.ChangeLanguage(Locale);
        }
    }

    /// <summary>
    /// Invoked from JS when the month is changed in the calendar.
    /// </summary>
    [JSInvokable]
    public async Task OnMonthChanged()
    {
        await ReloadDatesToHighlight();
    }

    /// <summary>
    /// Invoked from JS when the year is changed in the calendar.
    /// </summary>
    [JSInvokable]
    public async Task OnYearChanged()
    {
        await ReloadDatesToHighlight();
    }

    /// <summary>
    /// Disposes JS interop references and the DatePicker component.
    /// </summary>
    public async ValueTask DisposeAsync()
    {
        _dotNetRef?.Dispose();
        if (datePicker != null)
            await datePicker.DisposeAsync();
    }
    
    /// <summary>
    /// Highlights the specified dates in the calendar using JS interop.
    /// </summary>
    private async Task ReloadDatesToHighlight()
    {
        if (HighlightedDays == null)
            return;

        string chosenLocale = this.Locale ?? "en-US";

        //Console.WriteLine("chosenLocale:" + chosenLocale);

        var datesToHighlight = HighlightedDays
            .Select(d => new { annotation = d.Annotation, date = d.Value.ToString("MMMM d, yyyy", new CultureInfo(chosenLocale)) })
            .ToArray();

        //Console.WriteLine(System.Text.Json.JsonSerializer.Serialize(datesToHighlight));

        await JS.InvokeVoidAsync(
            "highlightFlatpickrDates",
            ".flatpickr-calendar",
            datesToHighlight,
            HighlightCssClass // Pass the class as an extra argument
        );
    }

    /// <summary>
    /// Optionally provides a CSS class for a given date. Not used in this implementation.
    /// </summary>
    private string GetDateClass(DateTime date)
    {
        return string.Empty;
    }

    /// <summary>
    /// Handles the date change event from the DatePicker and propagates it to the parent component.
    /// </summary>
    private async Task OnDateChanged(DateTime newValue)
    {
        SelectedDate = newValue;
        await SelectedDateChanged.InvokeAsync(newValue);
    }

    private DatePicker<DateTime>? datePicker;
    private DotNetObjectReference<CustomDatePicker>? _dotNetRef;
}


Notice the trick done to capture unmatched values in case some parameters of DatePicker in the custom date picker is missing and we still want the user of this component to set a parameter of the date picker component :


    /// 
    /// Additional attributes to be splatted onto the underlying DatePicker component.
    /// 
    [Parameter(CaptureUnmatchedValues = true)] 
    public Dictionary<string, object>? AdditionalAttributes { get; set; }


The calls to IJSRunTime to register callback script handlers will register callbacks for the component, this is done in this line :

_dotNetRef = DotNetObjectReference.Create(this);
await JS.InvokeVoidAsync("registerFlatpickrMonthChange", "input.flatpickr-input", _dotNetRef); 
await JS.InvokeVoidAsync("registerFlatpickrYearChange", "input.flatpickr-input", _dotNetRef);           

The following client side script is registeret into the global window object to provide script event handlers that will be called when the end-user changes selected year or month, either via the UI controls or just entering the date.

datepicker-highlight.js


window.highlightFlatpickrDates = (selector, dates, highlightCssClass) => {
    //debugger
    const calendar = document.querySelector(selector); 
    if (!calendar) {
        return; //Wait for Flatpickr to render days
    }
    //debugger
    setTimeout(() => {
        //
        dates.forEach(date => {
            //debugger
            const dayElem = calendar.querySelector(`.flatpickr-day[aria-label="${date.date}"]`);
            if (dayElem) {
                dayElem.classList.add(highlightCssClass);
                dayElem.setAttribute('title', date.annotation);
            }
        });
    }, 50);
};

window.registerFlatpickrMonthChange = (selector, dotNetHelper) => {
    const fpInput = document.querySelector(selector);
    if (!fpInput || !fpInput._flatpickr) {
        setTimeout(() => window.registerFlatpickrMonthChange(selector, dotNetHelper), 50);
        return;
    }
    fpInput._flatpickr.config.onMonthChange.push(function () {
        dotNetHelper.invokeMethodAsync('OnMonthChanged');
    });
};

window.registerFlatpickrYearChange = (selector, dotNetHelper) => {
    const fpInput = document.querySelector(selector);
    if (!fpInput || !fpInput._flatpickr) {
        setTimeout(() => window.registerFlatpickrYearChange(selector, dotNetHelper), 50);
        return;
    }
    fpInput._flatpickr.config.onYearChange.push(function () {
        dotNetHelper.invokeMethodAsync('OnYearChanged');
    });
};

The following test page test out the component.

StyledDatePicker.razor



@page "/"
@using BlazoriseDatePickerWithHolidays.Components
@using BlazoriseDatePickerWithHolidays.Service
@using System.Globalization
@using static BlazoriseDatePickerWithHolidays.Service.HolidayService
@inject IHolidayService HolidayService

<h3>Custom Date Picker with Highlighted Days</h3>

<p>

    <b>The date picker used here is from Blazorise library and customized to allow setting days to highlight including tooltips annotating a description of the date being highlighted.</b>
    <br />
    Blazorise DatePicker component is described here:
    <br /><br />
    <a href="https://blazorise.com/docs/components/date-picker">https://blazorise.com/docs/components/date-picker</a>
    <br /><br />
    The highlighted dates selected for this demo are Christian Holidays and other public days off in Norway.
    In Norwegian, these days off are called 'Offentlige hΓΈytidsdager'.<br />
    These days are marked with a pink background, white foreground and rounded corners. <br />
    Tooltips are added showing the Holiday name <br/>

</p>

<div class="container-fluid">
    <div class="row">
        <div class="col-md-2">
            <CustomDatePicker
                @bind-SelectedDate="selectedDate" 
                Locale="en-US"
                FirstDayOfWeek="DayOfWeek.Monday"
                InputMode="DateInputMode.DateTime"
                DisplayFormat="HH:mm dd.MM.yyyy"
                InputFormat="HH:mm dd.MM.yyyy"
                TimeAs24hr="true"
                HighlightedDays="_holidays"
                @ref="@_datePicker" />
        </div>
    </div>
</div>

@{
    var chosenLocale = new CultureInfo(_datePicker?.Locale ?? "en-US");
}

<p class="mt-3">Selected date <strong>@selectedDate.ToString("HH:mm dd.MM.yyyy", chosenLocale)</strong></p>

@code {
    private DateTime selectedDate = new DateTime(2025, 5, 4);
    private static int minYear = DateTime.Today.AddYears(-20).Year;
    private List<AnnotatedDateTime>? _holidays;

    private CustomDatePicker? _datePicker;

    protected override void OnParametersSet()
    {  
        _holidays = Enumerable.Range(minYear, 40)
            .SelectMany(y => HolidayService.GetHolidays(y))
            .ToList();
    }

}


The dates to select uses an implementation of IHolidayService. This implemented like this, note that this finds 'Offentlige hΓΈytidsdager' and (Christian-belief) holidays in Norway.

HolidayService.cs



namespace BlazoriseDatePickerWithHolidays.Service;

public interface IHolidayService
{
    DateTime AddWorkingDaysToDate(DateTime date, int days);
    List<string> GetHolidayNames();
    IEnumerable<HolidayService.AnnotatedDateTime> GetHolidays(int year);
    bool IsHoliday(DateTime date);
    bool IsWorkingDay(DateTime date);
}

public partial class HolidayService : IHolidayService
{

    private static MemoryCache<int, HashSet<AnnotatedDateTime>> holidays = new();

    private static readonly List<string> holidayNames = new List<string> {
            "1. nyttΓ₯rsdag",
            "PalmesΓΈndag",
            "Skjærtorsdag",
            "Langfredag",
            "1. pΓ₯skedag",
            "2. pΓ₯skedag",
            "Offentlig hΓΈytidsdag",
            "Grunnlovsdag",
            "Kristi Himmelfartsdag",
            "1. pinsedag",
            "2. pinsedag",
            "1. juledag",
            "2. juledag"
    };

    /// <summary>
    /// Adds the given number of working days to the given date. A working day is
    /// specified as a regular Norwegian working day, excluding weekends and all
    /// national holidays.
    /// 
    /// Example 1:
    /// - Add 5 working days to Wednesday 21.03.2007 -> Yields Wednesday
    /// 28.03.2007. (skipping saturday and sunday)
    /// 
    /// Example 2:
    /// - Add 5 working days to Wednesday 04.04.2007 (day before
    /// easter-long-weekend) -> yields Monday 16.04.2007 (skipping 2 weekends and
    /// 3 weekday holidays).
    /// </summary>
    /// <param name="date">The original date</param>
    /// <param name="days">The number of working days to add</param>
    /// <returns>The new date</returns>
    public DateTime AddWorkingDaysToDate(DateTime date, int days)
    {
        var localDate = date;
        for (var i = 0; i < days; i++)
        {
            localDate = localDate.AddDays(1);
            while (!IsWorkingDay(localDate))
            {
                localDate = localDate.AddDays(1);
            }
        }
        return localDate;
    }

    /// <summary>
    /// Will check if the given date is a working day. That is check if the given
    /// date is a weekend day or a national holiday.
    /// </summary>
    /// <param name="date">The date to check</param>
    /// <returns>true if the given date is a working day, false otherwise</returns>
    public bool IsWorkingDay(DateTime date)
    {
        return date.DayOfWeek != DayOfWeek.Saturday && date.DayOfWeek != DayOfWeek.Sunday
               && !IsHoliday(date);
    }

    public List<string> GetHolidayNames()
    {
        return holidayNames;
    }

    /// <summary>
    /// Check if given Date object is a holiday.
    /// </summary>
    /// <param name="date">date to check if is a holiday</param>
    /// <returns>true if holiday, false otherwise</returns>
    public bool IsHoliday(DateTime date)
    {
        var year = date.Year;
        var holidaysForYear = GetHolidaySet(year);
        foreach (var holiday in holidaysForYear)
        {
            if (CheckDate(date, holiday.Value))
            {
                return true;
            }
        }
        return false;
    }

    /// <summary>
    /// Return a sorted array of holidays for a given year.
    /// </summary>
    /// <param name="year">The year to get holidays for</param>
    /// <returns>Holidays, sorted by date</returns>
    public IEnumerable<AnnotatedDateTime> GetHolidays(int year)
    {
        var days = GetHolidaySet(year);
        var listOfHolidays = new List<AnnotatedDateTime>(days);
        listOfHolidays.Sort((date1, date2) => date1.Value.CompareTo(date2.Value));
        return listOfHolidays;
    }

    /// <summary>
    /// Get a set of holidays for a given year
    /// </summary>
    /// <param name="year">The year to get holidays for</param>
    /// <returns>Holidays for year</returns>
    private IEnumerable<AnnotatedDateTime> GetHolidaySet(int year)
    {
        if (holidays == null)
        {
            holidays = new MemoryCache<int, HashSet<AnnotatedDateTime>>();
        }
        if (holidays.Get(year) == null)
        {
            var yearSet = new HashSet<AnnotatedDateTime>();

            // Add set holidays.
            yearSet.Add(new AnnotatedDateTime("1. nyttΓ₯rsdag " + year, new DateTime(year, 1, 1)));
            yearSet.Add(new AnnotatedDateTime("Offentlig hΓΈytidsdag " + year, new DateTime(year, 5, 1)));
            yearSet.Add(new AnnotatedDateTime("Grunnlovsdag " + year, new DateTime(year, 5, 17)));
            yearSet.Add(new AnnotatedDateTime("1. juledag " + year, new DateTime(year, 12, 25)));
            yearSet.Add(new AnnotatedDateTime("2. juledag " + year, new DateTime(year, 12, 26)));

            // Add movable holidays - based on easter day.
            var easterDay = GetEasterDay(year);

            // Sunday before easter.
            yearSet.Add(new AnnotatedDateTime("PalmesΓΈndag " + year, easterDay.AddDays(-7)));

            // Thurday before easter.
            yearSet.Add(new AnnotatedDateTime("Skjærtorsdag " + year, easterDay.AddDays(-3)));

            // Friday before easter.
            yearSet.Add(new AnnotatedDateTime("Langfredag " + year, easterDay.AddDays(-2)));

            // Easter day.
            yearSet.Add(new AnnotatedDateTime("1. pΓ₯skedag " + year, easterDay));

            // Second easter day.
            yearSet.Add(new AnnotatedDateTime("2. pΓ₯skedag " + year, easterDay.AddDays(1)));

            // "Kristi himmelfart" day.
            yearSet.Add(new AnnotatedDateTime("Kristi Himmelfartsdag " + year, easterDay.AddDays(39)));

            // "Pinse" day.
            yearSet.Add(new AnnotatedDateTime("1. pinsedag " + year, easterDay.AddDays(49)));

            // Second "Pinse" day.
            yearSet.Add(new AnnotatedDateTime("2. pinsedag " + year, easterDay.AddDays(50)));

            holidays.Add(year, yearSet);
        }
        return holidays.GetAsValue(year)!;
    }

    /// <summary>
    ///  Calculates easter day (sunday) by using Spencer Jones formula found here:
    ///  http://no.wikipedia.org/wiki/P%C3%A5skeformelen
    /// </summary>
    /// <param name="year">year</param>
    /// <returns>easterday for year</returns>
    private DateTime GetEasterDay(int year)
    {
        int a = year % 19;
        int b = year / 100;
        int c = year % 100;
        int d = b / 4;
        int e = b % 4;
        int f = (b + 8) / 25;
        int g = (b - f + 1) / 3;
        int h = (19 * a + b - d - g + 15) % 30;
        int i = c / 4;
        int k = c % 4;
        int l = (32 + 2 * e + 2 * i - h - k) % 7;
        int m = (a + 11 * h + 22 * l) / 451;
        int n = (h + l - 7 * m + 114) / 31; // This is the month number.
        int p = (h + l - 7 * m + 114) % 31; // This is the date minus one.

        return new DateTime(year, n, p + 1);
    }

    private bool CheckDate(DateTime date, DateTime other)
    {
        return date.Day == other.Day && date.Month == other.Month;
    }

}


Also, some CSS rules are added here for the custom control :

App.css



.flatpickr-day.pink-day {
    background: #ff69b4 !important; /* Hot pink */   
    color: white !important;
    border-radius: 50%;
}

.addon-margin {
    margin-left: 0.25rem !important; /* Adjust as needed */
}


Finally, a screenshot showing how the Custom date picker works. We have highlighted dates in May 2025 here, I chose to generate holidays for +- 20 years here. Obviously, an optimization would be the possibility to only pass in the chose year of the date picker and not a wide range of years. This is however looking to be fast anyways and I believe you can pass in a large number of dates to highlight here. Hopefully, this article has given you more inspiration how to add highlighting of dates into the Blazorise Datepicker component for Blazor !

Sunday, 9 March 2025

Generating dropdowns for enums in Blazor

This article will look into generating dropdown for enums in Blazor. The repository for the source code listed in the article is here: https://github.com/toreaurstadboss/DallEImageGenerationImgeDemoV4 First off, a helper class for enums that will use the InputSelect control. The helper class will support setting the display text for enum options / alternatives via resources files using the display attribute.

Enumhelper.cs | C# source code



using DallEImageGenerationImageDemoV4.Models;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Forms;
using System.ComponentModel.DataAnnotations;
using System.Linq.Expressions;
using System.Resources;

namespace DallEImageGenerationImageDemoV4.Utility
{
  
    public static class EnumHelper
    {
      
        public static RenderFragment GenerateEnumDropDown<TEnum>(
            object receiver,
            TEnum selectedValue,
            Action<TEnum> valueChanged) 
            where TEnum : Enum
        {
            Expression<Func<TEnum>> onValueExpression = () => selectedValue;
            var onValueChanged = EventCallback.Factory.Create<TEnum>(receiver, valueChanged);
            return builder =>
            {
                // Set the selectedValue to the first enum value if it is not set
                if (EqualityComparer<TEnum>.Default.Equals(selectedValue, default))
                {
                    object? firstEnum = Enum.GetValues(typeof(TEnum)).GetValue(0);
                    if (firstEnum != null)
                    {
                        selectedValue = (TEnum)firstEnum;
                    }
                }

                builder.OpenComponent<InputSelect<TEnum>>(0);
                builder.AddAttribute(1, "Value", selectedValue);
                builder.AddAttribute(2, "ValueChanged", onValueChanged);
                builder.AddAttribute(3, "ValueExpression", onValueExpression);
                builder.AddAttribute(4, "class", "form-select");  // Adding Bootstrap class for styling
                builder.AddAttribute(5, "ChildContent", (RenderFragment)(childBuilder =>
                {
                    foreach (var value in Enum.GetValues(typeof(TEnum)))
                    {
                        childBuilder.OpenElement(6, "option");
                        childBuilder.AddAttribute(7, "value", value?.ToString());
                        childBuilder.AddContent(8, GetEnumOptionDisplayText(value)?.ToString()?.Replace("_", " ")); // Ensure the display text is clean
                        childBuilder.CloseElement();
                    }
                }));
                builder.CloseComponent();
            };
        }

        /// <summary>
        /// Retrieves the display text of an enum alternative 
        /// </summary>
        private static string? GetEnumOptionDisplayText<T>(T value)
        {
            string? result = value!.ToString()!; 

            var displayAttribute = value
                .GetType()
                .GetField(value!.ToString()!)
                ?.GetCustomAttributes(typeof(DisplayAttribute), false)?
                .OfType<DisplayAttribute>()
                .FirstOrDefault();
            if (displayAttribute != null)
            {
                if (displayAttribute.ResourceType != null && !string.IsNullOrWhiteSpace(displayAttribute.Name))
                {
                    result = new ResourceManager(displayAttribute.ResourceType).GetString(displayAttribute!.Name!);                    
                }
                else if (!string.IsNullOrWhiteSpace(displayAttribute.Name))
                {
                    result = displayAttribute.Name;
                }           
            }
            return result;          
        }


    }
}



The following razor component shows how to use this helper.


 <div class="form-group">
     <label for="Quality" class="form-class fw-bold">GeneratedImageQuality</label>
     @EnumHelper.GenerateEnumDropDown(this, homeModel.Quality,v => homeModel.Quality = v)
     <ValidationMessage For="@(() => homeModel.Quality)" class="text-danger" />
 </div>
 <div class="form-group">
     <label for="Size" class="form-label fw-bold">GeneratedImageSize</label>
     @EnumHelper.GenerateEnumDropDown(this, homeModel.Size, v => homeModel.Size = v)
     <ValidationMessage For="@(() => homeModel.Size)" class="text-danger" />
 </div>
 <div class="form-group">
     <label for="Style" class="form-label fw-bold">GeneratedImageStyle</label>
     @EnumHelper.GenerateEnumDropDown(this, homeModel.Style, v => homeModel.Style = v)
     <ValidationMessage For="@(() => homeModel.Style)" class="text-danger" />
 </div>


It would be possible to instead make a component than such a helper method that just passes a typeref parameter of the enum type. But using such a programmatic helper returning a RenderFragment. As the code shows, returning a builder which uses the RenderTreeBuilder let's you register the rendertree to return here. It is possible to use OpenComponent and CloseComponent. Using AddAttribute to add attributes to the InputSelect. And a childbuilder for the option values. Sometimes it is easier to just make such a class with helper method instead of a component. The downside is that it is a more manual process, it is similar to how MVC uses HtmlHelpers. What is the best option from using a component or such a RenderFragment helper is not clear, it is a technique many developers using Blazor should be aware of.

Saturday, 18 January 2025

Monitoring User Secrets inside Blazor

This article shows how you can add User Secrets for a Blazor app, or other related .NET client technology supporting them. User secrets are stored on the individual computer, so one do not have to expose them to others. They can still be shared between different people if they are told what the secrets are, but is practical in many cases where one for example do not want to expose the secrets such as a password, by checking it into
source code repositories. This is due to the fact as mentioned that the user secrets are as noted saved on the individual computer.

User secrets was added in .NET Core 1.0, already released in 2016. Not all developers are familiar with them. Inside Visual Studio 2022, you can right click on the Project of a solution and choose Manage User Secrets. When you choose that option, a file called secrets.json is opened. The file location for this file is shown if you hover over the file. The file location is saved here:

  
    %APPDATA%\Microsoft\UserSecrets\<user_secrets_id>\secrets.json
  
  
You can find the id here, the user_secrets_id, inside the project file (the .csproj file).
Example of such a setting below:
  
  <Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <UserSecretsId>339fab44-57cf-400c-89f9-46e037bb0392</UserSecretsId>
  </PropertyGroup>

</Project>

  

Let's first look at the way we can set up user secrets inside a startup file for the application. Note the usage of reloadOnChange set to true. And adding the user secrets as a singleton service wrapped inside IOptionsMonitor.

Program.cs



builder.Configuration.Sources.Clear();
builder.Configuration
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .AddJsonFile($"appsettings.{builder.Environment.EnvironmentName}.json", optional: true, reloadOnChange: true)
        .AddUserSecrets(Assembly.GetEntryAssembly()!, optional:false, reloadOnChange: true)
        .AddEnvironmentVariables();

builder.Services.Configure<ModelSecrets>(builder.Configuration.GetSection("ModelSecrets"));
builder.Services.AddSingleton<IOptionsMonitor<ModelSecrets>>, OptionsMonitor<ModelSecrets>>();



The Model secrets class looks like the following.



namespace StoringSecrets
{
    public class ModelSecrets
    {
        public string ApiKey { get; set; } = string.Empty;
    }
}


Home.razor.cs

Let's then look how we can fetch values from the user secrets. The code file for a file Home.razor is put in a file of its own, Home.razor.cs


using Microsoft.AspNetCore.Components;
using Microsoft.Extensions.Options;

namespace ToreAurstadIt.StoringSecrets.Components.Pages
{
    public partial class Home
    {
        [Inject]
        public required IOptionsMonitor<ModelSecrets> ModelSecretsMonitor { get; set; }

        public ModelSecrets? ModelSecrets  { get; set; }

        protected override async Task OnInitializedAsync()
        {
            ModelSecrets = ModelSecretsMonitor.CurrentValue;
            ModelSecretsMonitor.OnChange(updatedSecrets =>
            {
                ModelSecrets = updatedSecrets;
                InvokeAsync(StateHasChanged);

            });
            await Task.CompletedTask;
        }
    }
}

Note that IOptionsMonitor<ModelSecrets> is injected here and that in the OnInitializedAsync method, the injected value uses the OnChange method and and action callback then sets the value of the ModelSecrets and calls InvokeAsync method with StateHasChanged. We output the CurrentValue into the razor view of the Blazor app.

Home.razor



@page "/"

<PageTitle>Home</PageTitle>

<h1>Hello, world!</h1>

Welcome to your new app.

Your user secret is: 
<div>
    @ModelSecrets?.ApiKey
</div>


The secret.json file looks like this:

secrets.json



{
  "ModelSecrets": {
    "ApiKey": "SAMPLE_VALUE_UPDATE_9"
  }
}


A small app shows how this can be done, by changing the user secrets file and then reloading the page, changes should be immediately seen:

Saturday, 4 January 2025

Slider component for Blazor

I have added a Blazor component for Blazor, which uses INPUT of type range and additional CSS styling for more flexible setup of look and feel. The Blazor component is available on Github in my repo here:

https://github.com/toreaurstadboss/BlazorSlider

Blazor lib component

This repository contains Blazor lib Slider component that shows an input of type 'range'.

The slider got default horizontal layout, where the minimum value for the slider is shown to the most left of the scale, which goes along the x-axis for the slider got towards higher values and the maximum value is the value to the most right. The slider x-axis goes along the 'slider track'.

The value of the slider is indicated by the 'slider thumb'. Below the slider are shown 'tick marks', which are controlled by the Minimum and Maximum values and StepSize. Note that the supported data types are the data types that are IConvertible and struct, and the code expects types that can be converted to double. You can use integers for example, but also decimals or floats and so on. In addition, enums can be used, but it works only if your enum got consecutive values, for example 0,1,2,3,4 . The best results are if these consecutive values got the same StepSize. To start using the Blazor slider, add this using in your .razor file where you want to use the component.
 
@using BlazorSliderLib

Please note that the slider has been tested using Bootstrap, more specifically this version:

"bootstrap@5.3.3"
Here is sample markup you can add to test out the Blazor slider (3 sliders are rendered using a custom model and the updated values are shown in labels below :

    <div class="container"> 

        <div class="row">
            <div class="form-control col-md-4">
                <p><b>EQ5D-5L question 1.</b> <br />Mobility. Ability to walk.</p>
                <BlazorSliderLib.Slider T="Eq5dWalk" UseAlternateStyle="AlternateStyle.AlternateStyleInverseColorScale" Title="Ability to walk" ValueChanged="@((e) => UpdateEq5dQ1(e))"
                MinimumDescription="No Problems = The best ability to walk you can imagine" MaximumDescription="Incapable = The worst ability to walk you can imagine" />
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <p><b>EQ5D-5L question 6.</b> <br />We would like to how good or bad your health is TODAY.</p>
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <BlazorSliderLib.Slider T="int" UseAlternateStyle="AlternateStyle.AlternateStyle" Minimum="0" Maximum="100" @bind-Value="@(Model.Data.Eq5dq6)" Stepsize="5" Title="Your health today"
                MinimumDescription="0 = The worst health you can imagine" MaximumDescription="100 = The best health you can imagine" />
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <p><b>EQ5D-5L question 6.</b> <br />We would like to how good or bad your health is TODAY. V2 field.</p>
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <BlazorSliderLib.Slider T="int" Minimum="0" Maximum="100" ValueChanged="@((e) => UpdateEq5dq6V2(e))" Stepsize="5" Title="Your health today (v2 field)"
                MinimumDescription="0 = The worst health you can imagine" MaximumDescription="100 = The best health you can imagine" />
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <p>Value of Model.Data.Eq5dq1</p>
                @Model.Data.Eq5dq1
            </div>
        </div>

        <div class="row">
            <div class="form-control col-md-4"> <p>Value of Model.Data.Eq5d6</p>
                @Model.Data.Eq5dq6 
            </div> 
        </div>

        <div class="row">
            <div class="form-control col-md-4">
                <p>Value of Model.Data.Eq5d6V2</p>
                @Model.Data.Eq5dq6V2
            </div>
        </div>

    </div>

The different setup of sliders

The slider is set up either with an alternate style or using the default styling for sliders, that is, the slider uses an input type of 'range' and the default documented styling on Mozilla Developer Network (MDN) to render a Blazor slider. In addition, it is possible to set up the alternate style to use a inverted color range where higher values will get a reddish color and lower values will get a greenish color. The standard alternate style will show greenish colors for higher values. The following screenshot shows the possible styling that is possible. Note that the default styling is shown in the slider at the bottom, which will render a bit different in different browsers. In Chrome for example, the slider will render with a bluish color. In Edge Chromium, a grayish color is used for the 'slider tick' and 'slider thumb'. Screenshots showing the sliders: The following parameters can be used:
Title
Required. The title is shown below the slider component and centered horizontally along the center of the x-axis which the slider is oriented.
Value
The value of the slider. It can be data bound using either the @bind-Value directive attribute that supports two-way data binding. You can instead use the @ValueChanged event callback, if desired.
Minimum
The minimum value along the slider. It is default set to 0 for numbers. For enums, the lowest value is chosen of the enum (minimum enum alternative, converted to double internally).
Maximum
The maximum value along the slider. It is default set to 100 for numbers. For enums, the higheset value is chosen of the enum (maximum enum alternative, converted to double internally).
Stepsize
The step size for the slider. It is default set to 5 for numbers. For enums, it is set to 1. (note that internally the slider must use double values to work with the _tickmarks_, which expects double values).
ShowTickmarks
Shows tick marks for slider. It is default set to 'true'. Tick marks are generated from the values of Minimum, Maximum and StepSize.
MinimumDescription
Shows additionally description for the minimum value, shown as a small label below the slider. It will only be shown in the value is not empty.
UseAlternateStyle
If the UseAlternateStyle is set to either AlternateStyle and AlternateStyleInverseColorScale, alternate styling is used.

CSS rules to enable the slider

Actually, it is necessary to define a set of CSS rules to make the slider work. The slider's css rules are defined in two different files.

Default CSS rules

`Slider.css` The CSS rules below are taken from MDN Mozilla Developer Network page for the input type 'range' control. Input type 'range' control MDN article:

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/range

Additional settings are set up. The width is set to 100% so the slider can get as much horizontal space as possible and 'stretch'. There are also basic styles set up for both the tick label and datalist.The datalist is the tickmarks for the slider. The tick marks are automatically generated for the slider.


.sliderv2
{
    width:100%;
}

.sliderv2Label {
    font-weight: 400;
    text-align: center;
    left: 50%;
    font-size:0.7em;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, margin-bottom: 2px;
}

datalist {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    writing-mode: vertical-lr;
    width: 100%;
}

.tick-label {

    justify-content: space-between;
    font-size:0.6em;

    top: 20px; /* Adjust this value as needed */
}

input[type="range"] {
    width: 100%;
    margin: 0;
}


Alternate CSS rules

`SliderAlternate.css` The alternate CSS rules are setting up additional styling, where color encoding is used for the 'slider track' where higher values along the 'slider track' get a more 'greenish color', while lower values gets 'reddish values'. It is possible to set up the inverse color encoding here, with higher values getting 'reddish color'. Lower values gets more 'greenish colors' in this setup.


.alternate-style input[type="range"] {
    -webkit-appearance: none; /* Remove default styling */
    width: 100%;
    height: 8px;
    background: #ddd;
    outline: none;
    opacity: 0.7;
    transition: opacity .2s;
}

    .alternate-style input[type="range"]:hover {
        opacity: 1;
    }

    .alternate-style input[type="range"]::-webkit-slider-runnable-track {
        width: 100%;
        height: 8px;
        background: linear-gradient(to left, #A5D6A7, #FFF9C4, #FFCDD2); /* More desaturated gradient color */
        border: none;
        border-radius: 3px;
    }

        .alternate-style-inverse-colorscale input[type="range"]::-webkit-slider-runnable-track {
            background: linear-gradient(to right, #A5D6A7, #FFF9C4, #FFCDD2) !important; /* More desaturated gradient color, inverted color range */
        }


.alternate-style input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none; /* Remove default styling */
    appearance: none;
    width: 25px;
    height: 25px;
    background: #2E7D32; /* Even darker green thumb color */
    cursor: pointer;
    border-radius: 50%;
    margin-top: -15px !important; /* Move the thumb up */
}

    .alternate-style input[type="range"]::-moz-range-track {
        width: 100%;
        height: 8px;
        background: linear-gradient(to left, #A5D6A7, #FFF9C4, #FFCDD2); /* More desaturated gradient color */
        border: none;
        border-radius: 3px;
    }

        .alternate-style-inverse-colorscale input[type="range"]::-moz-range-track {
            background: linear-gradient(to right, #A5D6A7, #FFF9C4, #FFCDD2 !important; /* More desaturated gradient color, inverted color range */
        }

    .alternate-style input[type="range"]::-moz-range-thumb {
        width: 25px;
        height: 25px;
        background: #2E7D32; /* Even darker green thumb color */
        cursor: pointer;
        border-radius: 50%;
        transform: translateY(-15px); /* Move the thumb up */
    }


The implementation for the Blazor slider looks like this, in the codebehind file for the Slider:


using Microsoft.AspNetCore.Components;

namespace BlazorSliderLib
{

    /// <summary>
    /// Slider to be used in Blazor. Uses input type='range' with HTML5 element datalist and custom css to show a slider.
    /// To add tick marks, set the <see cref="ShowTickmarks"/> to true (this is default)
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public partial class Slider<T> : ComponentBase
        where T : struct, IComparable
    {

        /// <summary>
        /// Initial value to set to the slider, data bound so it can also be read out
        /// </summary>
        [Parameter]
        public T Value { get; set; }

        public double ValueAsDouble { get; set; }

        public double GetValueAsDouble()
        {
            if (typeof(T).IsEnum)
            {
                if (_isInitialized)
                {
                    var e = _enumValues.FirstOrDefault(v => Convert.ToDouble(v).Equals(Convert.ToDouble(Value)));
                    return Convert.ToDouble(Convert.ChangeType(Value, typeof(int)));
                }
                else
                {
                    return 0;
                }
            }
            else
            {
                return Convert.ToDouble(Value);
            }
        }        

        [Parameter, EditorRequired]
        public required string Title { get; set; }

        [Parameter]
        public string? MinimumDescription { get; set; }

        [Parameter]
        public string? MaximumDescription { get; set; }

        [Parameter]
        public double Minimum { get; set; } = typeof(T).IsEnum ? Enum.GetValues(typeof(T)).Cast<int>().Select(e => Convert.ToDouble(e)).Min() : 0.0;

        [Parameter]
        public double Maximum { get; set; } = typeof(T).IsEnum ? Enum.GetValues(typeof(T)).Cast<int>().Select(e => Convert.ToDouble(e)).Max() : 100.0;

        [Parameter]
        public double? Stepsize { get; set; } = typeof(T).IsEnum ? 1 : 5.0;

        [Parameter]
        public bool ShowTickmarks { get; set; } = true;

        [Parameter]
        public AlternateStyle UseAlternateStyle { get; set; } = AlternateStyle.None;

        [Parameter]
        public EventCallback<T> ValueChanged { get; set; }

        public List<double> Tickmarks { get; set; } = new List<double>();

        private List<T> _enumValues { get; set; } = new List<T>();

        private bool _isInitialized = false;

        private async Task OnValueChanged(ChangeEventArgs e)
        {
            if (e.Value == null)
            {
                return;
            }
            if (typeof(T).IsEnum && e.Value != null)
            {
                var enumValue = _enumValues.FirstOrDefault(v => Convert.ToDouble(v).Equals(Convert.ToDouble(e.Value))); 
                if (Enum.TryParse(typeof(T), enumValue.ToString(), out _)) {
                    Value = enumValue; //check that it was a non-null value set from the slider
                }
                else
                {
                    return; //if we cannot handle the enum value set, do not process further
                }
            }
            else
            {
                Value = (T)Convert.ChangeType(e.Value!, typeof(T));
            }

            ValueAsDouble = GetValueAsDouble();

            await ValueChanged.InvokeAsync(Value);
        }


        private string TickmarksId = "ticksmarks_" + Guid.NewGuid().ToString("N");

        protected override async Task OnParametersSetAsync()
        {
            if (_isInitialized)
            {
                return ; //initialize ONCE 
            }

            if (!typeof(T).IsEnum && Value.CompareTo(0) == 0)
            {
                Value = (T)Convert.ChangeType((Convert.ToDouble(Maximum) - Convert.ToDouble(Minimum)) / 2, typeof(T));
                ValueAsDouble = GetValueAsDouble();
            }

            if (Maximum.CompareTo(Minimum) < 1)
            {
                throw new ArgumentException("The value for parameter 'Maximum' is set to a smaller value than {Minimum}");
            }
            GenerateTickMarks();

            BuildEnumValuesListIfRequired();

            _isInitialized = true;

            await Task.CompletedTask;
        }

        private void BuildEnumValuesListIfRequired()
        {
            if (typeof(T).IsEnum)
            {
                foreach (var item in Enum.GetValues(typeof(T)))
                {
                    _enumValues.Add((T)item);
                }
            }
        }

        private void GenerateTickMarks()
        {
            Tickmarks.Clear();
            if (!ShowTickmarks)
            {
                return;
            }
            if (typeof(T).IsEnum)
            {
                int enumValuesCount = Enum.GetValues(typeof(T)).Length;
                double offsetEnum = 0;
                double minDoubleValue = Enum.GetValues(typeof(T)).Cast<int>().Select(e => Convert.ToDouble(e)).Min();
                double maxDoubleValue = Enum.GetValues(typeof(T)).Cast<int>().Select(e => Convert.ToDouble(e)).Max();
                double enumStepSizeCalculated = (maxDoubleValue - minDoubleValue) / enumValuesCount;

                foreach (var enumValue in Enum.GetValues(typeof(T)))
                {
                    Tickmarks.Add(offsetEnum);
                    offsetEnum += Math.Round(enumStepSizeCalculated, 0);
                }
                return;
            }

            for (double i = Convert.ToDouble(Minimum); i <= Convert.ToDouble(Maximum); i += Convert.ToDouble(Stepsize))
            {
                Tickmarks.Add(i);
            }

        }      

    }

    public enum AlternateStyle
    {
        /// <summary>
        /// No alternate style. Uses the ordinary styling for the slider (browser default of input type 'range')
        /// </summary>
        None,

        /// <summary>
        /// Applies alternate style, using in addition to the 'slider track' an additional visual hint with an additional 'slider track' right below that shows a reddish color for lowest parts of the scale to the slider and towards yellow and greenish hues for higher values
        /// The alternate style uses a larger 'slider thumb' and alternate style to the 'slider-track'. The alternate style gives a more interesting look, especially in Microsoft Edge Chromium.
        /// </summary>
        AlternateStyle,

        /// <summary>
        /// Similar in style to the alternate style, but uses the inverse scale for the colors along the slider
        /// </summary>
        AlternateStyleInverseColorScale
    }

}


The markup of the Slider looks like this:


@using Microsoft.AspNetCore.Components.Forms
@using BlazorSliderLib
@typeparam T where T : struct, IComparable

<div class="slider-container sliderv2 @((UseAlternateStyle == AlternateStyle.AlternateStyle || (UseAlternateStyle == AlternateStyle.AlternateStyleInverseColorScale))? "alternate-style" : "") @(UseAlternateStyle == AlternateStyle.AlternateStyleInverseColorScale ? "alternate-style-inverse-colorscale" : "")">
<input type="range" @bind="@ValueAsDouble" min="@Minimum" max="@Maximum" step="@Stepsize" list="@TickmarksId" @oninput="OnValueChanged" />
<datalist id="@TickmarksId">
    @{
        var itemIndex = 0;
    }
    @foreach (var value in Tickmarks){
        if (typeof(T).IsEnum){
            var itemLabel = _enumValues.ElementAt(itemIndex);
            <option class="tick-label" value="@value" label="@itemLabel"></option>
        }
        else {
            <option class="tick-label" value="@value" label="@value"></option>
        }
        itemIndex++;    
    }
</datalist>

<div class="row">
@if (!string.IsNullOrWhiteSpace(MinimumDescription)){
    <div class="col-md-4">
        <label class="sliderv2Label text-muted">@MinimumDescription</label>
    </div>
}
@if (!string.IsNullOrWhiteSpace(Title)){
    <div class="col-md-4">
        <label class="sliderv2Label text-muted" style="text-align:center">@Title: @Value</label>
    </div>
}

@if (!string.IsNullOrWhiteSpace(MaximumDescription)){
    <div class="col-md-4" style="text-align:right">
        <label class="sliderv2Label tet-muted text-end">@MaximumDescription</label>
    </div>
}

</div>

<link rel="stylesheet" href="_content/BlazorSliderLib/Slider.css" />
<link rel="stylesheet" href="_content/BlazorSliderLib/SliderAlternate.css" />

<link rel="shortcut icon" type="image/x-icon" href="favicon.ico"/>


</div>


The slider control is provided "as is" and is free to change and use of no charge.

https://github.com/toreaurstadboss/BlazorSlider?tab=MIT-1-ov-file#readme

Monday, 22 April 2024

Pii - Detecting Personally Identifiable Information using Azure Cognitive Services

This article will look at detecting Person Identifiable Information (Pii) using Azure Cognitive Services. I have created a demo using .NET Maui Blazor has been created and the Github repo is here:
https://github.com/toreaurstadboss/PiiDetectionDemo

Person Identifiable Information (Pii) is desired to detect and also redact, that is using censorship or obscuring Pii to prepare documents for publication. The Pii feature in Azure Cognitive Services is a part of the Language resource service. A quickstart for using Pii is available here:
https://learn.microsoft.com/en-us/azure/ai-services/language-service/personally-identifiable-information/quickstart?pivots=programming-language-csharp

After creating the Language resource, look up the keys and endpoints for you service. Using Azure CLI inside Cloud shell, you can enter this command to find the keys, in Azure many services has got two keys you can exchange with new keys through regeneration:

az cognitiveservices account keys list --resource-group SomeAzureResourceGroup --name SomeAccountAzureCognitiveServices
This is how you can query after endpoint of language resource using Azure CLI : az cognitiveservices account show --query "properties.endpoint" --resource-group SomeAzureResourceGroup --name SomeAccountAzureCognitiveServices
Next, the demo of this article. Connecting to the Pii Removal Text Analytics is possible using this Nuget package (REST calls can also be done manually): - Azure.AI.TextAnalytics version 5.3.0 Here is the other Nugets of my Demo included from the .csproj file :

PiiDetectionDemo.csproj


  <ItemGroup>
        <PackageReference Include="Azure.AI.TextAnalytics" Version="5.3.0" />
        <PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiVersion)" />
        <PackageReference Include="Microsoft.Maui.Controls.Compatibility" Version="$(MauiVersion)" />
        <PackageReference Include="Microsoft.AspNetCore.Components.WebView.Maui" Version="$(MauiVersion)" />
        <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="8.0.0" />
    </ItemGroup>


A service using this Pii removal feature is simply making use of a TextAnalyticsClient and method RecognizePiiEntitiesAsync.

PiiRemovalTextClientService.cs IPiiRemovalTextClientService.cs



using Azure;
using Azure.AI.TextAnalytics;

namespace PiiDetectionDemo.Util
{
    public interface IPiiRemovalTextAnalyticsClientService
    {
        Task<Response<PiiEntityCollection>> RecognizePiiEntitiesAsync(string? document, string? language);
    }
}


namespace PiiDetectionDemo.Util
{
    public class PiiRemovalTextAnalyticsClientService : IPiiRemovalTextAnalyticsClientService
    {

        private TextAnalyticsClient _client;

        public PiiRemovalTextAnalyticsClientService()
        {
            var azureEndpoint = Environment.GetEnvironmentVariable("AZURE_COGNITIVE_SERVICE_ENDPOINT");
            var azureKey = Environment.GetEnvironmentVariable("AZURE_COGNITIVE_SERVICE_KEY");

            if (string.IsNullOrWhiteSpace(azureEndpoint))
            {
                throw new ArgumentNullException(nameof(azureEndpoint), "Missing system environment variable: AZURE_COGNITIVE_SERVICE_ENDPOINT");
            }
            if (string.IsNullOrWhiteSpace(azureKey))
            {
                throw new ArgumentNullException(nameof(azureKey), "Missing system environment variable: AZURE_COGNITIVE_SERVICE_KEY");
            }

            _client = new TextAnalyticsClient(new Uri(azureEndpoint), new AzureKeyCredential(azureKey));
        }

        public async Task<Response<PiiEntityCollection>> RecognizePiiEntitiesAsync(string? document, string? language)
        {
            var piiEntities = await _client.RecognizePiiEntitiesAsync(document, language);
            return piiEntities;
        }

    }
}


The UI codebehind of the razor component page showing the UI looks like this:

Home.razor.cs


using Azure;
using Microsoft.AspNetCore.Components;
using PiiDetectionDemo.Models;
using PiiDetectionDemo.Util;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PiiDetectionDemo.Components.Pages
{
    public partial class Home
    {

        private IndexModel Model = new();
        private bool isProcessing = false;
        private bool isSearchPerformed = false;

        private async Task Submit()
        {
            isSearchPerformed = false;
            isProcessing = true;
            try
            {
                var response = await _piiRemovalTextAnalyticsClientService.RecognizePiiEntitiesAsync(Model.InputText, null);
                Model.RedactedText = response?.Value?.RedactedText;
                Model.UpdateHtmlRedactedText();
                Model.AnalysisResult = response?.Value;
                StateHasChanged();
            }
            catch (Exception ex)
            {
                await Console.Out.WriteLineAsync(ex.ToString());
            }
            isProcessing = false;
            isSearchPerformed = true;
        }

        private void removeWhitespace(ChangeEventArgs args)
        {
            Model.InputText = args.Value?.ToString()?.CleanupAllWhiteSpace();
            StateHasChanged();
        }



    }
}



To get the redacted or censored text void of any Pii that the Pii detection feature was able to detect, access the Value of type Azure.AI.TextAnalytics.PiiEntityCollection. Inside this object, the string RedactedText contains the censored / redacted text. The IndexModel looks like this :


using Azure.AI.TextAnalytics;
using Microsoft.AspNetCore.Components;
using PiiDetectionDemo.Util;
using System.ComponentModel.DataAnnotations;
using System.Text;

namespace PiiDetectionDemo.Models
{

    public class IndexModel
    {

        [Required]
        public string? InputText { get; set; }

        public string? RedactedText { get; set; }

        public string? HtmlRedactedText { get; set; }

        public MarkupString HtmlRedactedTextMarkupString { get; set; }

        public void UpdateHtmlRedactedText()
        {
            var sb = new StringBuilder(RedactedText);
            if (AnalysisResult != null && RedactedText != null)
            {
                foreach (var piiEntity in AnalysisResult.OrderByDescending(a => a.Offset))
                {
                    sb.Insert(piiEntity.Offset + piiEntity.Length, "</b></span>");
                    sb.Insert(piiEntity.Offset, $"<span style='background-color:lightgray;border:1px solid black;corner-radius:2px; color:{GetBackgroundColor(piiEntity)}' title='{piiEntity.Category}: {piiEntity.SubCategory} Confidence: {piiEntity.ConfidenceScore} Redacted Text: {piiEntity.Text}'><b>");
                }
            }
            HtmlRedactedText = sb.ToString()?.CleanupAllWhiteSpace();    
            HtmlRedactedTextMarkupString = new MarkupString(HtmlRedactedText ?? string.Empty);
        }

        private string GetBackgroundColor(PiiEntity piiEntity)
        {
            if (piiEntity.Category == PiiEntityCategory.PhoneNumber)
            {
                return "yellow";
            }
            if (piiEntity.Category == PiiEntityCategory.Organization)
            {
                return "orange";
            }
            if (piiEntity.Category == PiiEntityCategory.Address)
            {
                return "green";
            }
            return "gray";                   
        }

        public long ExecutionTime { get; set; }
        public PiiEntityCollection? AnalysisResult { get; set; }

    }
}




Frontend UI looks like this: Home.razor


@page "/"
@using PiiDetectionDemo.Util

@inject IPiiRemovalTextAnalyticsClientService _piiRemovalTextAnalyticsClientService;

<h3>Azure HealthCare Text Analysis - Pii detection feature - Azure Cognitive Services</h3>

<em>Pii = Person identifiable information</em>

<EditForm Model="@Model" OnValidSubmit="@Submit">
    <DataAnnotationsValidator />
    <ValidationSummary />

    <div class="form-group row">
        <label><strong>Text input</strong></label>
        <InputTextArea @oninput="removeWhitespace" class="overflow-scroll" style="max-height:500px;max-width:900px;font-size: 10pt;font-family:Verdana, Geneva, Tahoma, sans-serif" @bind-Value="@Model.InputText" rows="5" />
    </div>

    <div class="form-group row">
        <div class="col">
            <br />
            <button class="btn btn-outline-primary" type="submit">Run</button>
        </div>
        <div class="col">
        </div>
        <div class="col">
        </div>
    </div>

    <br />

    @if (isProcessing)
    {

        <div class="progress" style="max-width: 90%">
            <div class="progress-bar progress-bar-striped progress-bar-animated"
                 style="width: 100%; background-color: green">
                Retrieving result from Azure Text Analysis Pii detection feature. Processing..
            </div>
        </div>
        <br />

    }

    <div class="form-group row">
        <label><strong>Analysis result</strong></label>

        @if (isSearchPerformed)
        {
            <br />
            <b>Execution time took: @Model.ExecutionTime ms (milliseconds)</b>

            <br />
            <br />

            <b>Redacted text (Pii removed)</b>
            <br />

            <div class="form-group row">
               <label><strong>Categorized Pii redacted text</strong></label>
               <div>
               @Model.HtmlRedactedTextMarkupString
               </div>
            </div>

            <br />
            <br />

            <table class="table table-striped table-dark table-hover">
                <thead>
                <th>Pii text</th>
                <th>Category</th>
                <th>SubCategory</th>
                <th>Offset</th>
                <th>Length</th>
                <th>ConfidenceScore</th>
                </thead>
                <tbody>
                    @if (Model.AnalysisResult != null) {
                        @foreach (var entity in Model.AnalysisResult)
                        {
                            <tr>
                                <td>@entity.Text</td>
                                <td>@entity.Category.ToString()</td>
                                <td>@entity.SubCategory</td>
                                <td>@entity.Offset</td>
                                <td>@entity.Length</td>
                                <td>@entity.ConfidenceScore</td>                                        
                            </tr>
                        }
                    }
                </tbody>
            </table>

        }
    </div>

</EditForm>



The Demo uses Bootstrap 5 to build up a HTML table styled and showing the Azure.AI.TextAnalytics.PiiEntity properties.