---
id: 5a24c314108439a4d4036148
title: 将 Redux 连接到 Messages App
challengeType: 6
forumTopicId: 301427
dashedName: connect-redux-to-the-messages-app
---
# --description--
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。
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。
# --instructions--
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。
# --hints--
`AppWrapper` 应该渲染该到页面上。
```js
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
return mockedComponent.find('AppWrapper').length === 1;
})()
);
```
`Presentational` 应该渲染到页面上.
```js
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
return mockedComponent.find('Presentational').length === 1;
})()
);
```
`Presentational` 组件应渲染 `h2`、`input`、`button`、`ul` 四个元素。
```js
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
);
})()
);
```
`Presentational` 组件应接收 Redux store 的 `messages` 属性。
```js
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
const PresentationalComponent = mockedComponent.find('Presentational');
const props = PresentationalComponent.props();
return Array.isArray(props.messages);
})()
);
```
`Presentational` 组件应接收创建 action 的函数的 `submitMessage` 属性。
```js
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
const PresentationalComponent = mockedComponent.find('Presentational');
const props = PresentationalComponent.props();
return typeof props.submitNewMessage === 'function';
})()
);
```
# --seed--
## --after-user-code--
```jsx
ReactDOM.render(, document.getElementById('root'))
```
## --seed-contents--
```jsx
// Redux:
const ADD = 'ADD';
const addMessage = (message) => {
return {
type: ADD,
message: message
}
};
const messageReducer = (state = [], action) => {
switch (action.type) {
case ADD:
return [
...state,
action.message
];
default:
return state;
}
};
const store = Redux.createStore(messageReducer);
// React:
class Presentational extends React.Component {
constructor(props) {
super(props);
this.state = {
input: '',
messages: []
}
this.handleChange = this.handleChange.bind(this);
this.submitMessage = this.submitMessage.bind(this);
}
handleChange(event) {
this.setState({
input: event.target.value
});
}
submitMessage() {
this.setState((state) => {
const currentMessage = state.input;
return {
input: '',
messages: state.messages.concat(currentMessage)
};
});
}
render() {
return (
);
}
};
// React-Redux:
const mapStateToProps = (state) => {
return { messages: state }
};
const mapDispatchToProps = (dispatch) => {
return {
submitNewMessage: (newMessage) => {
dispatch(addMessage(newMessage))
}
}
};
const Provider = ReactRedux.Provider;
const connect = ReactRedux.connect;
// Define the Container component here:
class AppWrapper extends React.Component {
constructor(props) {
super(props);
}
render() {
// Complete the return statement:
return (null);
}
};
```
# --solutions--
```jsx
// Redux:
const ADD = 'ADD';
const addMessage = (message) => {
return {
type: ADD,
message: message
}
};
const messageReducer = (state = [], action) => {
switch (action.type) {
case ADD:
return [
...state,
action.message
];
default:
return state;
}
};
const store = Redux.createStore(messageReducer);
// React:
class Presentational extends React.Component {
constructor(props) {
super(props);
this.state = {
input: '',
messages: []
}
this.handleChange = this.handleChange.bind(this);
this.submitMessage = this.submitMessage.bind(this);
}
handleChange(event) {
this.setState({
input: event.target.value
});
}
submitMessage() {
this.setState((state) => {
const currentMessage = state.input;
return {
input: '',
messages: state.messages.concat(currentMessage)
};
});
}
render() {
return (
);
}
};
// React-Redux:
const mapStateToProps = (state) => {
return { messages: state }
};
const mapDispatchToProps = (dispatch) => {
return {
submitNewMessage: (newMessage) => {
dispatch(addMessage(newMessage))
}
}
};
const Provider = ReactRedux.Provider;
const connect = ReactRedux.connect;
const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
class AppWrapper extends React.Component {
constructor(props) {
super(props);
}
render() {
return (
);
}
};
```