ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
11 KiB
11 KiB
id, title, challengeType, forumTopicId, dashedName
| id | title | challengeType | forumTopicId | dashedName |
|---|---|---|---|---|
| 5a24c314108439a4d4036149 | 将局部状态提取到 Redux 中 | 6 | 301428 | extract-local-state-into-redux |
--description--
胜利就在眼前了！请回顾一下为管理 React messages app 的状态写的 Redux 代码。现在有了连接好的 Redux，你还要从Presentational组件中提取状态管理到 Redux，在Presentational组件内处理本地状态。
--instructions--
在Presentational组件中，先删除本地state中的messages属性，被删的 messages 将由 Redux 管理。接着，修改submitMessage()方法，使该方法从this.props那里分发submitNewMessage()；从本地state中传入当前消息输入作为参数。因本地状态删除了messages属性，所以在调用this.setState()时也要删除该属性。最后，修改render()方法，使其所映射的消息是从props接收的，而不是state
完成这些更改后，我们的应用会实现 Redux 管理应用的状态，但它继续运行着相同的功能。此示例还阐明了组件获得本地状态的方式，即在自己的状态中继续跟踪用户本地输入。由此可见，Redux 为 React 提供了很有用的状态管理框架。先前，你仅使用 React 的本地状态也实现了相同的结果，这在应付简单的应用时通常是可行的。但是，随着应用变得越来越大，越来越复杂，应用的状态管理也变得非常困难，Redux 就是为解决这样的问题而诞生的。
--hints--
AppWrapper应该渲染该到页面。
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
return mockedComponent.find('AppWrapper').length === 1;
})()
);
Presentational 应该渲染到页面上.
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。
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 的消息属性。
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submitMessage属性。
assert(
(function () {
const mockedComponent = Enzyme.mount(React.createElement(AppWrapper));
const PresentationalComponent = mockedComponent.find('Presentational');
const props = PresentationalComponent.props();
return typeof props.submitNewMessage === 'function';
})()
);
Presentational组件的状态应包含一个初始化为空字符串的input属性。
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
);
})()
);
键入input元素应更新Presentational组件的状态。
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__'
);
};
在Presentational组件上 dispatch submitMessage应更新 Redux store 并清除本地状态中的输入。
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 === ''
);
};
Presentational组件应渲染 Redux store 中的messages
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
);
};
--seed--
--after-user-code--
ReactDOM.render(<AppWrapper />, document.getElementById('root'))
--seed-contents--
// 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:
const Provider = ReactRedux.Provider;
const connect = ReactRedux.connect;
// Change code below this line
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) => ({
input: '',
messages: state.messages.concat(state.input)
}));
}
render() {
return (
<div>
<h2>Type in a new Message:</h2>
<input
value={this.state.input}
onChange={this.handleChange}/><br/>
<button onClick={this.submitMessage}>Submit</button>
<ul>
{this.state.messages.map( (message, idx) => {
return (
<li key={idx}>{message}</li>
)
})
}
</ul>
</div>
);
}
};
// Change code above this line
const mapStateToProps = (state) => {
return {messages: state}
};
const mapDispatchToProps = (dispatch) => {
return {
submitNewMessage: (message) => {
dispatch(addMessage(message))
}
}
};
const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
class AppWrapper extends React.Component {
render() {
return (
<Provider store={store}>
<Container/>
</Provider>
);
}
};
--solutions--
// 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:
const Provider = ReactRedux.Provider;
const connect = ReactRedux.connect;
// Change code below this line
class Presentational extends React.Component {
constructor(props) {
super(props);
this.state = {
input: ''
}
this.handleChange = this.handleChange.bind(this);
this.submitMessage = this.submitMessage.bind(this);
}
handleChange(event) {
this.setState({
input: event.target.value
});
}
submitMessage() {
this.props.submitNewMessage(this.state.input);
this.setState({
input: ''
});
}
render() {
return (
<div>
<h2>Type in a new Message:</h2>
<input
value={this.state.input}
onChange={this.handleChange}/><br/>
<button onClick={this.submitMessage}>Submit</button>
<ul>
{this.props.messages.map( (message, idx) => {
return (
<li key={idx}>{message}</li>
)
})
}
</ul>
</div>
);
}
};
// Change code above this line
const mapStateToProps = (state) => {
return {messages: state}
};
const mapDispatchToProps = (dispatch) => {
return {
submitNewMessage: (message) => {
dispatch(addMessage(message))
}
}
};
const Container = connect(mapStateToProps, mapDispatchToProps)(Presentational);
class AppWrapper extends React.Component {
render() {
return (
<Provider store={store}>
<Container/>
</Provider>
);
}
};