142 lines
5.2 KiB
Markdown
142 lines
5.2 KiB
Markdown
---
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id: 5a24c314108439a4d4036144
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title: Use Provider to Connect Redux to React
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challengeType: 6
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isRequired: false
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videoUrl: ''
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localeTitle: 使用Provider将Redux连接到React
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---
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## Description
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<section id="description">在上一个挑战中，您创建了一个Redux存储来处理messages数组并创建了一个用于添加新消息的操作。下一步是提供对Redux存储的React访问以及分派更新所需的操作。 React Redux提供了<code>react-redux</code>包来帮助完成这些任务。 React Redux提供了一个小API，它有两个关键特性： <code>Provider</code>和<code>connect</code> 。另一个挑战包括<code>connect</code> 。 <code>Provider</code>是React Redux的一个包装组件，它包装了你的React应用程序。然后，此包装器允许您访问整个组件树中的Redux <code>store</code>和<code>dispatch</code>功能。 <code>Provider</code>需要两个道具，Redux商店和应用程序的子组件。为App组件定义<code>Provider</code>可能如下所示： <blockquote> <Provider store = {store}> <br> <应用/> <br> </提供商> </blockquote></section>
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## Instructions
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<section id="instructions">代码编辑器现在显示过去几个挑战中的所有Redux和React代码。它包括Redux存储，操作和<code>DisplayMessages</code>组件。唯一的新部分是底部的<code>AppWrapper</code>组件。使用此顶级组件从<code>ReactRedux</code>呈现<code>Provider</code> ，并将Redux存储作为prop传递。然后将<code>DisplayMessages</code>组件渲染为子级。完成后，您应该看到React组件呈现给页面。 <strong>注意：</strong> React Redux在此处可用作全局变量，因此您可以使用点表示法访问提供程序。编辑器中的代码利用了这一点并将其设置为一个常量<code>Provider</code>供您在<code>AppWrapper</code>渲染方法中使用。 </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>应该渲染。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find("AppWrapper").length === 1; })(), "The <code>AppWrapper</code> should render.");'
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- text: <code>Provider</code>包装器组件应该具有传递给它的<code>store</code>支柱，等于Redux存储。
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testString: 'getUserInput => assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return getUserInput("index").replace(/\s/g,"").includes("<Providerstore={store}>"); })(), "The <code>Provider</code> wrapper component should have a prop of <code>store</code> passed to it, equal to the Redux store.");'
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- text: <code>DisplayMessages</code>应该呈现为<code>AppWrapper</code> 。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find("AppWrapper").find("DisplayMessages").length === 1; })(), "<code>DisplayMessages</code> should render as a child of <code>AppWrapper</code>.");'
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- text: <code>DisplayMessages</code>组件应该呈现h2，input，button和<code>ul</code>元素。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find("div").length === 1 && mockedComponent.find("h2").length === 1 && mockedComponent.find("button").length === 1 && mockedComponent.find("ul").length === 1; })(), "The <code>DisplayMessages</code> component should render an h2, input, button, and <code>ul</code> element.");'
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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 Code:
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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
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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 Code:
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class DisplayMessages 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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const Provider = ReactRedux.Provider;
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class AppWrapper extends React.Component {
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// render the Provider here
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// change code above this line
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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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console.info('after the test');
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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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// solution required
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```
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</section>
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