patbi / redux_learning

Redux_Learning

WE COVER

*Full React Redux with testing Tutorial *

Table of Contents

1. What is Redux
2. What Redux include
3. Implement simplest Redux
4. Create Redux store with ReactJs
5. Adding Actions and Reducers to store
6. Redux Devtool
7. Combine Reducers
8. Providers
9. Connects
10. Redux thunk
11. Testing

1. What is Redux — #

• Redux is a predictable state container for JavaScript apps.
• Run in different environments(client, server and native)
• It is tiny (2KB, including dependencies)

2. What Redux include — #

3. Three principes of Redux — #

4. Implement simplest Redux — #

• Create React App

npm install create-react-app && create-react-app your_application_name

• Run Project

npm start

• Install Redux

npm install redux

5. Adding Actions and Reducers to store — #

• In your src->index.js

import {createStore} from 'redux';

Next create store

const store = createStore();

An error will be displayed due to the absence of the reducer function. to correct this error you just have to create the reducer function as follows, before create store.

const reducer = () => {}

const store = createStore(reducer)

console.log(store);

• can see

dispatch, subscribe, getState, replaceReducer...

• We're going to look at the getState

console.log(store.getState());

• undefined message -> because our application does not yet have a state

• So we create our state this way

const reducer = () => {
	return {name:'Patrick'}
}

• run

console.log(store.getState());

• So we can see our state.

• Then we move on to our state update.

const reducer = (state, actions) => {
	 if(actions.type=== 'UPDATE_NAME'){
		return {name:actions.payload}
	 }
	return {name:'Patrick'}
}

• add the method dispatch() for update

store.dispatch({type:'UPDATE_NAME', payload:'Isaac'})

console.log(store.getState());

So the three elements to remember are the following:

• Create reducer

• Create store

• Create actions

6. Redux Devtool — #

redux-devtools-extension

Next step Combine Reducers

7. Combine Reducers — #

So what does this step consist of? Just manipulating two reducers. And to do that we proceed as follows:

add combineReducers in import elements like this

import {createStore, combineReducers} from 'redux';

Create two reducer like this

• reducer one

const personReducer = (state ={}, {type, payload}) => {
	if(type === 'UPDATE_PERSON'){
		return {name:payload}
	}
	return state
}

• reducer two

const gameReducer = (state = {}, {type, payload}) => {
	if(type === 'UPDATE_GAME'){
		return {name:payload}
	}
	return state
}

Next we use combineReducers like this

const AllReducers = combineReducers({game:gameReducer, person:personReducer})

Next Initialize state like this

const InitialStates = {
   game:{name:'Football'},
   person:{name:'Patrick'},
}

Next create store like this

const store = createStore(AllReducers, InitialStates)

We can quickly check what's going on from our console with

console.log(store.getState());

Next we add actions that will allow us to modify our initial state. Like This

store.dispatch({type:'UPDATE_PERSON', payload:'Isaac'})

Then we can observe the changes with a

console.log(store.getState());

So what have we improved?

8 & 9. Providers - Connects #

• The architecture of the redux project

• We have installed react-redux to better handle the Provider & Connect

npm install react-redux --save

Then, as previously announced, the following milestones have just been exported and imported.

• Create reducer

• Create store

• Create actions

But also to have our tool, we went on this page to get

redux-devtools-extension

src -> store-> index.js

const store = createStore(
   AllReducers, 
   InitialStates, 
   window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__())

And to operate our store we just did this.

in src -> index.js

import store from './store/index.js';
import {Provider} from 'react-redux'

ReactDOM.render(
	<Provider store={store}>
	<App />
	</Provider>

, document.getElementById('root'));	

And to operate our state we just did this.

in src -> App.js

import React from 'react';
import './App.css';
import store from './store/index';
import update_person from './store/actions/personActions';
import update_game from './store/actions/gameActions';
import {connect} from 'react-redux';

function updatePerson () {
  store.dispatch(update_person);
}

function updateGame () {
  store.dispatch(update_game);
}



function App() {
  return (
    <div className="App">
        <h1>Redux Tutorial </h1>

        Person Name : {store.getState().person.name}
        <button onClick={updatePerson}>update person </button>

        <br/><br/>

        Game Name : {store.getState().game.name}
        <button onClick={updateGame}>update game </button>
    </div>
  );
}

const mapStateToProps = state => {
  return state
}

export default connect(mapStateToProps)(App);

10. Redux Thunk — #

In order to be able to execute asynchronous actions, like a request to an external API we need to use a middleware which is redux-thunk

Install redux-thunk

npm install redux-thunk --save	

After this installation we'll need to import

• applyMiddleware & compose from redux like this

src -> store -> index.js

import {createStore, combineReducers, applyMiddleware, compose} from 'redux';

Next import thunk from 'redux-thunk' like this

src -> store -> index.js

import thunk from 'redux-thunk';

Next create userReducer like this

import {UPDATE_USER} from '../actions/userActions'

const userReducer = (state ={}, {type, payload}) => {
	switch(type) {
		case UPDATE_USER:
			return payload
		default:
			return state
	}
}

export default userReducer;

Next create userActions like this

export const UPDATE_USER = 'UPDATE_USER'

const fetch_user = (dispatch) => {
	fetch('https://reqres.in/api/users')
		.then(res => res.json())
		.then(res => dispatch({type:UPDATE_USER, payload:res.data}))
}

export default fetch_user;

Next update personReducer like this

import {UPDATE_PERSON} from '../actions/personActions'

const personReducer = (state ={}, {type, payload}) => {
	switch(type) {
		case UPDATE_PERSON:
			return Object.assign({},state,{name:payload})
		default:
			return state
	}
}

export default personReducer;

Next update index.js like this

src -> store > index.js

import {createStore, combineReducers, applyMiddleware, compose} from 'redux';
import personReducer from './reducers/personReducer';
import gameReducer from './reducers/gameReducer';
import userReducer from './reducers/userReducer';
import thunk from 'redux-thunk';


const AllReducers = combineReducers({game:gameReducer, person:personReducer, users:userReducer})

const InitialStates = {
	game:{name:'Football'},
	person:{name:'Patrick', email:'[email protected]'},
	users:[]
}

const middleware = [thunk]

const store = createStore(AllReducers, InitialStates, compose(applyMiddleware
	(...middleware), window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()))

export default store;

Next update App.js like this

src -> App.js

import React from 'react';
import './App.css';
import update_person from './store/actions/personActions';
import update_game from './store/actions/gameActions';
import fetch_user from './store/actions/userActions';
import {connect} from 'react-redux';

function App(props) {
  return (
    <div className="App">
        <h1>Redux Tutorial </h1>

        Person Name : {props.person.name}
        <button onClick={props.updatePerson}>update person </button>

        <br/><br/>

        Game Name : {props.game.name}
        <button onClick={props.updateGame}>update game </button>
    
        <br/><br/>

        Users : <button onClick={props.fetchUsers}>Fetch Users </button>

        {
          props.users.length === 0 ? <p>No User found</p>:

          props.users.map(user => <p key={user.id}>{user.id} - {user.first_name} - {user.email}</p>)
        }

    </div>
  );
}

const mapStateToProps = state => {
    return {
      game:state.game,
      
      person:state.person,

      users:state.users
    }
}

const mapDispatchToProps = dispatch => {
  return {
      updateGame: () => {dispatch(update_game)},
      updatePerson: () => {dispatch(update_person)},
      fetchUsers: () => {dispatch(fetch_user)}
  }
}



export default connect(mapStateToProps, mapDispatchToProps)(App);

11. Testing — #

So it's great what we're doing here.

• In order to do the testing we have to install jest like this:

npm install jest babel-jest --save-dev

Next step

At the root of the project we create the file

.babelrc and config

{
	"presets":["@babel/preset-env"]
}

Next step

In the package.json change the config of the "scripts": like this:

 "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "jest",
    "test:watch": "npm test -- --watch",
    "eject": "react-scripts eject"
  },

Now we can start with the first test "test actions" like this:

• create src -> store -> actions -> person.test.js and add config like this :

import update_person, {UPDATE_PERSON} from './personActions'

describe('actions',()=>{
	it('should return the action for person',()=>{
		const expectedAction = {
			type: UPDATE_PERSON,
			payload:'Isaac'
		}
		expect(update_person).toEqual(expectedAction)
	})
})

To run the test we're just doing

npm run test:watch

• select all test 'option -> a'

And we have this result

Next step Now we can start with the second test "test reducer" like this:

• create src -> store -> reducers -> person-reducer.test.js and add config like this :

import personReducer from './personReducer'
import {UPDATE_PERSON} from '../actions/personActions'

describe('reducer',()=>{
   it('should update person name only',()=>{
   	const initialState = {name:'Patrick', email:'[email protected]'}
   	expect(
   		personReducer(initialState,{
   			type: UPDATE_PERSON,
   			payload:'Isaac'
   		})
   	)
   	.toEqual({name:'Isaac', email:'[email protected]'})
   })
})

And we have this result

• Official Redux Website

Official Redux Website

• Next Course on TypeScript

Understand_TypeScript-

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