267 lines
13 KiB
Markdown
267 lines
13 KiB
Markdown
---
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id: 5a24c314108439a4d4036149
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title: Extract Local State into Redux
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challengeType: 6
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isRequired: false
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forumTopicId: 301428
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localeTitle: Извлечь локальное состояние в Redux
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---
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## Description
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<section id='description'>
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Вы почти закончили! Напомним, что вы написали весь код Redux, чтобы Redux мог контролировать управление вашим приложением React messages. Теперь, когда Redux подключен, вам нужно извлечь управление состоянием из компонента <code>Presentational</code> и в Redux. В настоящее время вы подключены к Redux, но вы управляете состоянием локально в составе <code>Presentational</code> компонента.
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</section>
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## Instructions
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<section id='instructions'>
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В компоненте <code>Presentational</code> сначала удалите свойство <code>messages</code> в локальном <code>state</code> . Эти сообщения будут управляться Redux. Затем измените метод <code>submitMessage()</code> так, чтобы он отправил <code>submitNewMessage()</code> из <code>this.props</code> и передал текущее сообщение из локального <code>state</code> в качестве аргумента. Поскольку вы удалили <code>messages</code> из локального состояния, удалите свойство <code>messages</code> из вызова <code>this.setState()</code> здесь. Наконец, измените метод <code>render()</code> чтобы он отображал сообщения, полученные из <code>props</code> а не <code>state</code> . После внесения этих изменений приложение будет продолжать функционировать одинаково, за исключением того, что Redux управляет состоянием. В этом примере также показано, как компонент может иметь локальное <code>state</code> : ваш компонент по-прежнему отслеживает ввод пользователя локально в своем собственном <code>state</code> . Вы можете видеть, как Redux предоставляет полезную структуру управления государственными ресурсами поверх React. Вы достигли того же результата, используя сначала локальное состояние React, и это обычно возможно с помощью простых приложений. Однако, поскольку ваши приложения становятся все больше и сложнее, так же как и ваше управление состоянием, и это проблема, которую решает Redux.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: The <code>AppWrapper</code> should render to the page.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find('AppWrapper').length === 1; })());
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- text: The <code>Presentational</code> component should render an <code>h2</code>, <code>input</code>, <code>button</code>, and <code>ul</code> elements.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find('Presentational').length === 1; })());
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- text: The <code>Presentational</code> component should render an <code>h2</code>, <code>input</code>, <code>button</code>, and <code>ul</code> elements.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const PresentationalComponent = mockedComponent.find('Presentational'); return ( PresentationalComponent.find('div').length === 1 && PresentationalComponent.find('h2').length === 1 && PresentationalComponent.find('button').length === 1 && PresentationalComponent.find('ul').length === 1 ); })());
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- text: The <code>Presentational</code> component should receive <code>messages</code> from the Redux store as a prop.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const PresentationalComponent = mockedComponent.find('Presentational'); const props = PresentationalComponent.props(); return Array.isArray(props.messages); })());
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- text: The <code>Presentational</code> component should receive the <code>submitMessage</code> action creator as a prop.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const PresentationalComponent = mockedComponent.find('Presentational'); const props = PresentationalComponent.props(); return typeof props.submitNewMessage === 'function'; })());
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- text: The state of the <code>Presentational</code> component should contain one property, <code>input</code>, which is initialized to an empty string.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const PresentationalState = mockedComponent.find('Presentational').instance().state; return typeof PresentationalState.input === 'string' && Object.keys(PresentationalState).length === 1; })());
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- text: Typing in the <code>input</code> element should update the state of the <code>Presentational</code> component.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const testValue = ''__MOCK__INPUT__''; const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const causeChange = (c, v) => c.find(''input'').simulate(''change'', { target: { value: v }}); let initialInput = mockedComponent.find(''Presentational'').find(''input''); const changed = () => { causeChange(mockedComponent, testValue); return waitForIt(() => mockedComponent )}; const updated = await changed(); const updatedInput = updated.find(''Presentational'').find(''input''); assert(initialInput.props().value === '''' && updatedInput.props().value === ''__MOCK__INPUT__''); }; '
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- text: Dispatching the <code>submitMessage</code> on the <code>Presentational</code> component should update Redux store and clear the input in local state.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); let beforeProps = mockedComponent.find(''Presentational'').props(); const testValue = ''__TEST__EVENT__INPUT__''; const causeChange = (c, v) => c.find(''input'').simulate(''change'', { target: { value: v }}); const changed = () => { causeChange(mockedComponent, testValue); return waitForIt(() => mockedComponent )}; const clickButton = () => { mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => mockedComponent )}; const afterChange = await changed(); const afterChangeInput = afterChange.find(''input'').props().value; const afterClick = await clickButton(); const afterProps = mockedComponent.find(''Presentational'').props(); assert(beforeProps.messages.length === 0 && afterChangeInput === testValue && afterProps.messages.pop() === testValue && afterClick.find(''input'').props().value === ''''); }; '
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- text: The <code>Presentational</code> component should render the <code>messages</code> from the Redux store.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); let beforeProps = mockedComponent.find(''Presentational'').props(); const testValue = ''__TEST__EVENT__INPUT__''; const causeChange = (c, v) => c.find(''input'').simulate(''change'', { target: { value: v }}); const changed = () => { causeChange(mockedComponent, testValue); return waitForIt(() => mockedComponent )}; const clickButton = () => { mockedComponent.find(''button'').simulate(''click''); return waitForIt(() => mockedComponent )}; const afterChange = await changed(); const afterChangeInput = afterChange.find(''input'').props().value; const afterClick = await clickButton(); const afterProps = mockedComponent.find(''Presentational'').props(); assert(beforeProps.messages.length === 0 && afterChangeInput === testValue && afterProps.messages.pop() === testValue && afterClick.find(''input'').props().value === '''' && afterClick.find(''ul'').childAt(0).text() === testValue); }; '
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='jsx-seed'>
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```jsx
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// Redux:
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const ADD = 'ADD';
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const addMessage = (message) => {
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return {
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type: ADD,
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message: message
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}
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};
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const messageReducer = (state = [], action) => {
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switch (action.type) {
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case ADD:
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return [
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...state,
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action.message
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];
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default:
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return state;
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}
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};
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const store = Redux.createStore(messageReducer);
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// React:
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const Provider = ReactRedux.Provider;
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const connect = ReactRedux.connect;
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// Change code below this line
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class Presentational extends React.Component {
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constructor(props) {
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super(props);
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this.state = {
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input: '',
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messages: []
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}
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this.handleChange = this.handleChange.bind(this);
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this.submitMessage = this.submitMessage.bind(this);
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}
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handleChange(event) {
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this.setState({
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input: event.target.value
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});
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}
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submitMessage() {
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this.setState({
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input: '',
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messages: this.state.messages.concat(this.state.input)
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});
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}
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render() {
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return (
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<div>
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<h2>Type in a new Message:</h2>
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<input
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value={this.state.input}
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onChange={this.handleChange}/><br/>
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<button onClick={this.submitMessage}>Submit</button>
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<ul>
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{this.state.messages.map( (message, idx) => {
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return (
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<li key={idx}>{message}</li>
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)
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})
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}
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</ul>
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</div>
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);
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}
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};
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// Change code above this line
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const mapStateToProps = (state) => {
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return {messages: state}
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};
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const mapDispatchToProps = (dispatch) => {
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return {
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submitNewMessage: (message) => {
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dispatch(addMessage(message))
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}
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}
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};
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const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
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class AppWrapper extends React.Component {
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render() {
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return (
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<Provider store={store}>
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<Container/>
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</Provider>
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);
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}
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};
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```
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</div>
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### After Tests
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<div id='jsx-teardown'>
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```jsx
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ReactDOM.render(<AppWrapper />, document.getElementById('root'))
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```jsx
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// Redux:
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const ADD = 'ADD';
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const addMessage = (message) => {
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return {
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type: ADD,
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message: message
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}
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};
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const messageReducer = (state = [], action) => {
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switch (action.type) {
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case ADD:
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return [
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...state,
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action.message
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];
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default:
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return state;
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}
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};
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const store = Redux.createStore(messageReducer);
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// React:
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const Provider = ReactRedux.Provider;
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const connect = ReactRedux.connect;
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// Change code below this line
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class Presentational extends React.Component {
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constructor(props) {
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super(props);
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this.state = {
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input: ''
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}
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this.handleChange = this.handleChange.bind(this);
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this.submitMessage = this.submitMessage.bind(this);
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}
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handleChange(event) {
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this.setState({
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input: event.target.value
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});
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}
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submitMessage() {
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this.props.submitNewMessage(this.state.input);
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this.setState({
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input: ''
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});
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}
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render() {
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return (
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<div>
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<h2>Type in a new Message:</h2>
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<input
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value={this.state.input}
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onChange={this.handleChange}/><br/>
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<button onClick={this.submitMessage}>Submit</button>
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<ul>
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{this.props.messages.map( (message, idx) => {
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return (
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<li key={idx}>{message}</li>
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)
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})
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}
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</ul>
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</div>
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);
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}
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};
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// Change code above this line
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const mapStateToProps = (state) => {
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return {messages: state}
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};
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const mapDispatchToProps = (dispatch) => {
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return {
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submitNewMessage: (message) => {
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dispatch(addMessage(message))
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}
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}
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};
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const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
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class AppWrapper extends React.Component {
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render() {
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return (
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<Provider store={store}>
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<Container/>
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</Provider>
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);
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}
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};
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```
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</section>
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