169 lines
10 KiB
Markdown
169 lines
10 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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videoUrl: ''
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localeTitle: 将本地状态提取到Redux
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---
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## Description
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<section id="description">你几乎完成！回想一下，您编写了所有Redux代码，以便Redux可以控制React消息应用程序的状态管理。现在Redux已连接，您需要从<code>Presentational</code>组件中提取状态管理并进入Redux。目前，您已连接Redux，但您正在<code>Presentational</code>组件中本地处理状态。 </section>
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## Instructions
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<section id="instructions">在<code>Presentational</code>组件中，首先，删除本地<code>state</code>中的<code>messages</code>属性。这些消息将由Redux管理。接下来，修改<code>submitMessage()</code>方法，以便从<code>this.props</code>调度<code>submitNewMessage()</code> ，并将当前消息输入作为参数传入本地<code>state</code> 。因为你删除<code>messages</code>从本地状态，删除<code>messages</code>从调用属性<code>this.setState()</code>在这里。最后，修改<code>render()</code>方法，使其映射到从<code>props</code>而不是<code>state</code>接收的消息。一旦做出这些更改，除了Redux管理状态之外，应用程序将继续运行相同的功能。这个例子也说明组件可以如何具有本地<code>state</code> ：你的组件还是本地跟踪用户输入自己的<code>state</code> 。您可以看到Redux如何在React之上提供有用的状态管理框架。您最初仅使用React的本地状态获得了相同的结果，这通常可以通过简单的应用程序实现。但是，随着您的应用程序变得越来越大，越来越复杂，您的状态管理也是如此，这就是Redux解决的问题。 </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>应该呈现给页面。
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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 to the page.");'
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- text: <code>Presentational</code>组件应呈现<code>h2</code> ， <code>input</code> ， <code>button</code>和<code>ul</code>元素。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find("Presentational").length === 1; })(), "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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- text: <code>Presentational</code>组件应呈现<code>h2</code> ， <code>input</code> ， <code>button</code>和<code>ul</code>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 ); })(), "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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- text: <code>Presentational</code>组件应该从Redux商店接收<code>messages</code>作为道具。
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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); })(), "The <code>Presentational</code> component should receive <code>messages</code> from the Redux store as a prop.");'
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- text: <code>Presentational</code>组件应该接收<code>submitMessage</code>操作创建者作为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"; })(), "The <code>Presentational</code> component should receive the <code>submitMessage</code> action creator as a prop.");'
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- text: <code>Presentational</code>组件的状态应包含一个属性<code>input</code> ，该属性初始化为空字符串。
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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; })(), "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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- text: 输入<code>input</code>元素应该更新<code>Presentational</code>组件的状态。
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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__", "Typing in the <code>input</code> element should update the state of the <code>Presentational</code> component."); }; '
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- text: 在<code>Presentational</code>组件上调度<code>submitMessage</code>应更新Redux存储并清除本地状态的输入。
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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 === "", "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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- text: <code>Presentational</code>组件应该呈现来自Redux存储的<code>messages</code> 。
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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, "The <code>Presentational</code> component should render the <code>messages</code> from the Redux store."); }; '
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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 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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