Thursday 20 December 2018

React Native apps with Expo - Radio buttons

This article will present how you can add Radio buttons into your React Native app. I am using Expo to build the React Native app and Visual Studio code as the editor and IDE. You can run this app by downloading the Expo app from App Store and run the following sample by opening the Camera on your mobile and scan the QR code. This will launch Expo app and run the app. WidgetDemos - React Native app with radio buttons demo First off, you can install Expo using npm and the following command: npm install expo-cli --global You can initialize a project using these two commands: expo init MyRadioButtonProject cd MyRadioButtonProject expo start Expo's website contains good documentation here: We can use the built in React Native control SegmentedControlIOS from React native and the following code:

import React, { Component } from 'react';
import { StyleSheet, Text, View, SegmentedControlIOS } from 'react-native';

export default class Widget extends Component {

    constructor(props) {
        super(props);

    this.state = {
            selectedMoreFruitIndex: 0,
        };

    }

    setMoreFruitIndex(event) {
        this.setState({ selectedMoreFruitIndex: event.nativeEvent.selectedSegmentIndex })
    };

   render(){

   return (
            <View>

                <SegmentedControlIOS
                    values={['banana', 'apple']}
                    selectedIndex={this.state.selectedMoreFruitIndex}
                    onChange={(event) => this.setMoreFruitIndex(event)}
                />

                
            </View >
        );

  };

..


The SegmentControlIOS is simple to get started with, but it is not so easy to set up with compound objects, it only supports a string array. Hence, you cannot specify a label and a value to each radio button item. Instead use the SegmentedControls from the 'react-native-radio-buttons' package. We import this npm package using: npm install react-native-radio-buttons --save The npm package has got a home and documentation here: https://www.npmjs.com/package/react-native-radio-buttons First off, we define an array of fruit objects and put these into a state variable (array of objects) inside the constructor

 constructor(props) { 
..
 let moreFruits = [{ label: 'Strawberry', value: 'Strawberry' },
        { label: 'Melon', value: 'Melon' },
        { label: 'Pineapple', value: 'Pineapple' },
        { label: 'Grapes', value: 'Grapes' },
        ];

        this.state = {
            selectedFruit: 'Pick your favorite fruit',
            selectedMoreFruitIndex: 0,
            selectedMoreFruit: null,
            moreFruits: moreFruits
        } 

.. }
We use the SegmentedControls by importing at the top and defining it inside the View returned in the render method:

import RadioButtons, { SegmentedControls } from 'react-native-radio-buttons'; //RadioButtons not needed in this example

//..inside views of render

  <SegmentedControls
                    options={this.state.moreFruits}
                    direction='row'
                    onSelection={option => this.setSelectedOption(option)}
                    selectedOption={this.state.selectedMoreFruit}
                    extractText={(option) => option.label}
                ></SegmentedControls>

The method setSelectedOption and more can be read in the code listing below of Widget.js. I include also App.js below, the starting component: Widget.js
import React, { Component } from 'react';
import { StyleSheet, Text, View, TextInput, Button, RadioGroup, TouchableWithoutFeedback, SegmentedControlIOS } from 'react-native';
import { Dropdown } from 'react-native-material-dropdown';
import PropTypes from 'prop-types';
import { withStyles } from '@material-ui/core/styles';
import RadioButtons, { SegmentedControls } from 'react-native-radio-buttons';

export default class Widget extends Component {

    constructor(props) {
        super(props);


        let moreFruits = [{ label: 'Strawberry', value: 'Strawberry' },
        { label: 'Melon', value: 'Melon' },
        { label: 'Pineapple', value: 'Pineapple' },
        { label: 'Grapes', value: 'Grapes' },
        ];

        this.state = {
            selectedFruit: 'Pick your favorite fruit',
            reasonFruit: '',
            isFruitButtonClicked: 'no',
            selectedMoreFruitIndex: 0,
            moreFruits: moreFruits
        }
    }

    setSelectedOption(selectedOption) {
        var selectedMoreFruit = this.state.moreFruits.find(item => item.label == selectedOption.label);
        this.setState({ selectedMoreFruit: selectedMoreFruit })
    }

    renderOption(option, selected, onSelect, index) {
        const style = selected ? { backgroundColor: 'blue' } : { backgroundColor: 'red' };

        return (
            <TouchableWithoutFeedback onPress={onSelect} key={index}>
                <Text style={style}>{option.label}</Text>
            </TouchableWithoutFeedback>
        );
    }

    renderContainer(optionNodes) {
        return <View>optionNodes</View>;
    }

    setMoreFruitIndex(event) {
        this.setState({ selectedMoreFruitIndex: event.nativeEvent.selectedSegmentIndex })
    }


    render() {
        let data = [
            { label: 'Banana', value: 'Banana' },
            { label: 'Apple', value: 'Apple' },
            { label: 'Kiwi', value: 'Kiwi' }

        ];

        return (
            <View>

                <SegmentedControlIOS
                    values={['one', 'two']}
                    selectedIndex={this.state.selectedMoreFruitIndex}
                    onChange={(event) => this.setMoreFruitIndex(event)}
                />

                <Text>Selected option of react-native-radio-buttons: {this.state.selectedMoreFruit ? this.state.selectedMoreFruit.value : 'no fruit'}</Text>

                <SegmentedControls
                    options={this.state.moreFruits}
                    direction='row'
                    onSelection={option => this.setSelectedOption(option)}
                    selectedOption={this.state.selectedMoreFruit}
                    extractText={(option) => option.label}
                ></SegmentedControls>

                <Text style={{ fontWeight: 'bold' }}>Select favorite fruit then</Text>
                <Dropdown onChangeText={(val) => this.setState({ selectedFruit: val })} style={{ backgroundColor: 'aliceblue' }} data={data} />
                <Text>You selected: {this.state.selectedFruit}</Text>
                <Text></Text>


                <Text>Reason for fruit choice: {this.state.reasonFruit}</Text>
                <TextInput onChangeText={(val) => this.setState({ reasonFruit: val })} style={{ borderColor: 'black', borderRadius: 4, borderWidth: 1, backgroundColor: 'aliceblue' }} value={this.state.reasonFruit}></TextInput>

                <Text></Text>




                {/* <Button color="#841584" accessibilityLabel="Click this button!" onPress={(val) => this.setState({ isFruitButtonClicked: 'yes' })} title="Fruit button" />
                <Text>Is Fruit button clicked: {this.state.isFruitButtonClicked}</Text> */}

            </View >
        );
    }

    sayHello(val) {
        this.setState({ selectedFruit: 'You selected: ' + val })
    }


}

App.js

import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
import Widget from './Widget'
import { Col, Row, Grid } from 'react-native-easy-grid';

export default class App extends React.Component {
  render() {
    return (
      // Try setting `alignItems` to 'flex-start'
      // Try setting `justifyContent` to `flex-end`.
      // Try setting `flexDirection` to `row`.
      <View style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'stretch',
      }}>
        <View style={{ width: '80%', height: 50 }}>
          <Text style={{ fontSize: 18, flexWrap: 'wrap' }} >Welcome to the React Native apps demo!</Text>
        </View>
        <View style={{ height: 150 }}>
          <Widget />
        </View>
        <View style={{ height: 100 }} />
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    flexDirection: 'column',
    backgroundColor: '#fff',
    alignItems: 'stretch'
  },
});


Lastly, remember to set the selected object in the correct manner, using the find method for example on the state variable. This to ensure we are pointing at the right selected object in the SegmentedControls control.

   setSelectedOption(selectedOption) {
        var selectedMoreFruit = this.state.moreFruits.find(item => item.label == selectedOption.label);
        this.setState({ selectedMoreFruit: selectedMoreFruit })
    }

Thursday 22 November 2018

Displaying branch history in Git

I desired to have an easy branch log today. The following alias commands makes this easier. These go under the [alias] section in the .gitconfig file you are using in your repository.

latest = "!f() { echo "Latest \"${1:-11}\" commits accross all branches:"; git log  --abbrev-commit --date=relative --branches --all --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset%n' -n ${1:-11};  } ; f"
logbranch = "!f() { echo "Latest \"${1:-11}\" commits in current branch against master:"; git log master..${1:git branch}  --abbrev-commit --date=relative  --pretty=format:'%C(yellow)%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(white blue bold)<%an>%Creset%n' -n ${1:-11};  } ; f"

git logbranch will display only the latest commit for the specified branch or defaulting to the current branch, defaulting to last 11 commits using a shell function. Note that we compare against the master branch. And we get the following sample output:

Sunday 4 November 2018

Closing branches in Git

Git unlike Mercurial has no builtin support for closing branches. This leads to a proliferation of branches and running git branch -a to view remote branches or git branch will show ever more branches. Actually, closing a branch in Git can be supported through the use of tags. We decide to keep the tag for future use, so that we can use it to check out a new branch from this tag. Another way would of course be to just delete a brach local and/or remote, but that is not the same as closing a branch. Closing a branch in Mercurial still makes it possible to reopen it again for later work. Anyways, in this article, I will show two aliases which can be used to close a branch, either both local and remote or just remote. Put the following into the [alias] section of your .gitConfig file:

closebranch = "!w() { echo Attempting to close local and remote branch: $1 Processing...; echo Checking the branch $1 out..; git checkout $1; echo Trying to create a new tag archive/$1; git tag archive/\"$1\"; git push origin archive/\"$1\"; echo Deleting the local branch $1; git branch -d $1;  echo Deleting the remote branch $1; git push origin --delete $1; echo Done. To restore the closed branch later, enter: git checkout -b MyNewBranch archive/\"$1\"; }; w"

closebranchpassive = "!w() { echo Attempting to close local and remote branch: $1 Processing...; echo Checking the branch $1 out..; git checkout $1; echo Trying to create a new tag archive/$1; git tag archive/\"$1\"; git push origin archive/$1; echo Deleting the local branch $1;   echo Deleting the remote branch $1;  echo Done. To restore the closed branch later, enter: git checkout -b MyNewBranch archive/\"$1\"; }; w"

closeremotebranch =  "!w() { echo Attempting to close remote branch: $1 Processing...; echo Checking the branch $1 out..; git checkout $1;  echo Trying to create a new tag archive/$1; git tag archive/\"$1\"; git push origin archive/\"$1\"; echo Deleting the remote branch $1; git push origin --delete $1; echo Done. To restore the closed branch later, enter: git checkout -b MyNewBranch archive/\"$1\"; }; w"

What we do here is the following:
  • Check out the branch to close
  • Tag this branch as archive/branchname
  • Important - push the tag the remote e.g. origin in the provided aliased commands above
  • (Delete the local branch)
  • Delete the remote branch
  • Display a friendly output message how to restore the branch later through a tag
What we use here is a shell function in each alias. This allows us to do multiple commands in Git through a simple aliased command. Say you want to close a local and remote branch called MyBranchToBeClosed. Just enter: git closebranch MyBranchToBeClosed If you just want to close the remote branch and keep the local one, enter: git closeremotebranch MyBranchToBeClosed To restore the branch MyBranchToBeClosed (which now is actually closed!) later, just enter: git checkout -b MyRestoredBranch archive/MyBranchToBeClosed This lets you keep old branch around as tags and not proliferate the branch listings. We however have moved the branch(es) over to tags prefixed with archive/ I wish Git was simpler to use sometimes so we did not have to use such hacks, closing branches should be easy.