301 lines
6.9 KiB
Markdown
301 lines
6.9 KiB
Markdown
---
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id: 5a24c314108439a4d4036148
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title: 将 Redux 连接到 Messages App
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challengeType: 6
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forumTopicId: 301427
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dashedName: connect-redux-to-the-messages-app
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---
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# --description--
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知道如何使用 `connect` 连接 React 和 Redux 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 `Presentational`，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， 它们只负责执行接收 props 的函数来实现 UI 的呈现。 相比之下，容器组件用来连接到 Redux 上。 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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# --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 `Presentational`，即展示层组件。 创建一个新组件，保存在名为 `Container` 的常量中。 这个常量用 `connect` 把 `Presentational` 组件和 Redux 连接起来。 然后，在`AppWrapper` 中渲染 React Redux 的 `Provider`组件， 给 `Provider` 传入 Redux `store` 属性并渲染 `Container` 为子组件。 设置完所有内容后，将再次看到消息应用程序渲染到页面上。
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# --hints--
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`AppWrapper` 应该渲染该到页面上。
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
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return mockedComponent.find('AppWrapper').length === 1;
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})()
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);
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```
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`Presentational` 应该渲染到页面上.
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
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return mockedComponent.find('Presentational').length === 1;
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})()
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);
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```
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`Presentational` 组件应渲染 `h2`、`input`、`button`、`ul` 四个元素。
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
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const PresentationalComponent = mockedComponent.find('Presentational');
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return (
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PresentationalComponent.find('div').length === 1 &&
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PresentationalComponent.find('h2').length === 1 &&
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PresentationalComponent.find('button').length === 1 &&
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PresentationalComponent.find('ul').length === 1
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);
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})()
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);
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```
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`Presentational` 组件应接收 Redux store 的 `messages` 属性。
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
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const PresentationalComponent = mockedComponent.find('Presentational');
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const props = PresentationalComponent.props();
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return Array.isArray(props.messages);
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})()
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);
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```
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`Presentational` 组件应接收创建 action 的函数的 `submitMessage` 属性。
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
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const PresentationalComponent = mockedComponent.find('Presentational');
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const props = PresentationalComponent.props();
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return typeof props.submitNewMessage === 'function';
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})()
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);
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```
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# --seed--
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## --after-user-code--
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```jsx
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ReactDOM.render(<AppWrapper />, document.getElementById('root'))
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```
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## --seed-contents--
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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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this.setState((state) => {
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const currentMessage = state.input;
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return {
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input: '',
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messages: state.messages.concat(currentMessage)
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};
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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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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 (null);
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}
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};
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```
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# --solutions--
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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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this.setState((state) => {
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const currentMessage = state.input;
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return {
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input: '',
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messages: state.messages.concat(currentMessage)
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};
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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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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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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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