94 lines
3.7 KiB
Markdown
94 lines
3.7 KiB
Markdown
---
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id: 5a24c314108439a4d4036147
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title: 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: 将Redux连接到React
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---
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## Description
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<section id="description">现在您已经编写了<code>mapStateToProps()</code>和<code>mapDispatchToProps()</code>函数，您可以使用它们将<code>state</code>和<code>dispatch</code>映射到您的某个React组件的<code>props</code> 。 React Redux的<code>connect</code>方法可以处理此任务。此方法采用两个可选参数： <code>mapStateToProps()</code>和<code>mapDispatchToProps()</code> 。它们是可选的，因为您可能拥有只需要访问<code>state</code>但不需要分派任何操作的组件，反之亦然。要使用此方法，请将函数作为参数传递，并立即使用组件调用结果。这种语法有点不寻常，看起来像： <code>connect(mapStateToProps, mapDispatchToProps)(MyComponent)</code> <strong>注意：</strong>如果要省略<code>connect</code>方法的其中一个参数，则在其位置传递<code>null</code> 。 </section>
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## Instructions
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<section id="instructions">代码编辑器具有<code>mapStateToProps()</code>和<code>mapDispatchToProps()</code>函数以及一个名为<code>Presentational</code>的新React组件。使用<code>ReactRedux</code>全局对象中的<code>connect</code>方法将此组件连接到Redux，并立即在<code>Presentational</code>组件上调用它。将结果分配给名为<code>ConnectedComponent</code>的新<code>const</code> ，该<code>const</code>表示连接的组件。就是这样，现在你已经连接到Redux了！尝试将<code>connect</code>的参数更改为<code>null</code>并观察测试结果。 </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>Presentational</code>组件应该呈现。
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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.");'
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- text: <code>Presentational</code>组件应通过<code>connect</code>接收prop <code>messages</code> 。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const props = mockedComponent.find("Presentational").props(); return props.messages === "__INITIAL__STATE__"; })(), "The <code>Presentational</code> component should receive a prop <code>messages</code> via <code>connect</code>.");'
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- text: <code>Presentational</code>组件应通过<code>connect</code>接收prop <code>submitNewMessage</code> 。
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const props = mockedComponent.find("Presentational").props(); return typeof props.submitNewMessage === "function"; })(), "The <code>Presentational</code> component should receive a prop <code>submitNewMessage</code> via <code>connect</code>.");'
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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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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 mapStateToProps = (state) => {
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return {
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messages: state
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}
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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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class Presentational 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 <h3>This is a Presentational Component</h3>
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}
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};
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const connect = ReactRedux.connect;
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// change code below this line
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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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