266 lines
7.4 KiB
Markdown
266 lines
7.4 KiB
Markdown
---
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id: 5a24c314108439a4d4036148
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title: Connect Redux to the Messages App
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challengeType: 6
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isRequired: false
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forumTopicId: 301427
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localeTitle: 将 Redux 连接到 Messages App
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---
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## Description
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<section id='description'>
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知道<code>connect</code>怎么实现 React 和 Redux 的连接后，我们可以在 React 组件中应用上面学到的内容。
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在上一课，连接到 Redux 的组件命名为<code>Presentational</code>，这个命名不是任意的，这样的术语通常是指未直接连接到 Redux 的 React 组件，他们只负责执行接收 props 的函数来实现 UI 的呈现。与上一挑战相比，本挑战需要把容器组件连接到 Redux。这些组件通常负责把 actions 分派给 store，且经常给子组件传入 store state 属性。
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</section>
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## Instructions
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<section id='instructions'>
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到目前为止，我们的编辑器上已包含了整个章节的代码，唯一不同的是，React 组件被重新命名为<code>Presentational</code>，即展示层组件。创建一个新组件，保存在名为<code>Container</code>的常量中。这个常量用<code>connect</code>把<code>Presentational</code>组件和 Redux 连接起来。然后，在<code>AppWrapper</code>中渲染 React Redux 的<code>Provider</code>组件，给<code>Provider</code>传入 Redux<code>store</code>属性并渲染<code>Container</code>为子组件。完成这些，消息 app 应用会再次渲染页面。
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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: <code>AppWrapper</code>应渲染该页面。
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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: <code>Presentational</code>组件应渲染<code>h2</code>、<code>input</code>、<code>button</code>、<code>ul</code>四个元素。
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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: <code>Presentational</code>组件应渲染<code>h2</code>、<code>input</code>、<code>button</code>、<code>ul</code>四个元素。
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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: <code>Presentational</code>组件应接收 Redux store 的<code>消息</code>属性。
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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: <code>Presentational</code>组件应接收创建 action 的函数<code>submitMessage</code>属性。
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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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```
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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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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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const currentMessage = this.state.input;
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this.setState({
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input: '',
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messages: this.state.messages.concat(currentMessage)
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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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// React-Redux:
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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: (newMessage) => {
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dispatch(addMessage(newMessage))
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}
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}
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};
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const Provider = ReactRedux.Provider;
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const connect = ReactRedux.connect;
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// 在此定义 Container 组件：
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class AppWrapper extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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// 完成返回声明：
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return (null);
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}
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};
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```
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</div>
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### After Test
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<div id='jsx-teardown'>
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```js
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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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```js
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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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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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const currentMessage = this.state.input;
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this.setState({
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input: '',
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messages: this.state.messages.concat(currentMessage)
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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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// React-Redux:
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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: (newMessage) => {
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dispatch(addMessage(newMessage))
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}
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}
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};
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const Provider = ReactRedux.Provider;
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const connect = ReactRedux.connect;
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// define the Container component here:
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const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
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class AppWrapper extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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// complete the return statement:
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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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