Getting Started with React, Redux and Immutable: a Test-Driven Tutorial (Part 2)
翻译版本,原文请见
](https://ww3.sinaimg.cn/large/006tNc79ly1fds4960hm8j30xc0b4weu.jpg)
Image由[egghead.io提供](http://egghead.io/)
这是第二部分的内容.
在第一部分,我们罗列了app的UI,开发和单元测试的基础.
我们看到了app的state通过React的props向下传递到单个的组件,用户的actions声明为回调函数,因此app的逻辑和UI分离开来了.
Redux的工作流介绍
在这一点上,我们的UI是没有交互操作的:尽管我们已经测试了如果一个item如果被设定为completed,它将给文本划线,但是这里还没有方法邀请用户来完成它:
- state tree通过
props定义了UI和action回调函数. - 用户的actions,例如点击,被发送到action creator,action被它范式化.
- redux action被传递到reducer实现实际的app逻辑
- reducer更新state tree,dispatch state到store.
- UI根据store里的新state tree来更新UI
Redux working flos
设定初始化state
我们的第一个action将会允许我们在Redux store里正确的设置初始化state
,我们将会创建store.
Redux中的action是一个信息的载体(payload).action由一个JSON对象有一个type属性,描述action到底是做什么的,还有一部分是app需要的信息.在我们的实例中,type被设定为SET_STATE,我们可以添加一个state对象包含需要的state:
{
type: 'SET_STATE',
state: {
todos: [
{id: 1, text: 'React', status: 'active', editing: false},
{id: 2, text: 'Redux', status: 'active', editing: false},
{id: 3, text: 'Immutable', status: 'active', editing: false},
],
filter: 'all'
}
}
这个action会被dispatch到一个reducer,reducer角色的是识别和实施和action对应的逻辑代码.
让我们为reducer来写单元测试代码
test/reducer_spec.js
import {List, Map, fromJS} from 'immutable';
import {expect} from 'chai';
import reducer from '../src/reducer';
describe('reducer', () => {
it('handles SET_STATE', () => {
const initialState = Map();
const action = {
type: 'SET_STATE',
state: Map({
todos: List.of(
Map({id: 1, text: 'React', status: 'active'}),
Map({id: 2, text: 'Redux', status: 'active'}),
Map({id: 3, text: 'Immutable', status: 'completed'})
)
})
};
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}));
});
});
为了方便一点,state使用单纯JS对象,而不是使用Immutable数据结构.让我们的reducer来处理转变.最后,reducer将会优雅的处理undefined初始化state:
test/reducer_spec.js
// ...
describe('reducer', () => {
// ...
it('handles SET_STATE with plain JS payload', () => {
const initialState = Map();
const action = {
type: 'SET_STATE',
state: {
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}
};
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}));
});
it('handles SET_STATE without initial state', () => {
const action = {
type: 'SET_STATE',
state: {
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}
};
const nextState = reducer(undefined, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}));
});
});
我们的reducer将会匹配接收的actions的type,如果type是SET_STATE,当前的state和action运载的state融合在一起:
src/reducer.js
import {Map} from 'immutable';
function setState(state, newState) {
return state.merge(newState);
}
export default function(state = Map(), action) {
switch (action.type) {
case 'SET_STATE':
return setState(state, action.state);
}
return state;
}
现在我们不得不把reducer连接到我们的app,所以当app启动初始化state.这里实际是第一次使用Redux库,安装一下
npm install —save redux@3.3.1 react-redux@4.4.1
src/index.jsx
import React from 'react';
import ReactDOM from 'react-dom';
import {List, Map} from 'immutable';
import {createStore} from 'redux';
import {Provider} from 'react-redux';
import reducer from './reducer';
import {TodoAppContainer} from './components/TodoApp';
// We instantiate a new Redux store
const store = createStore(reducer);
// We dispatch the SET_STATE action holding the desired state
store.dispatch({
type: 'SET_STATE',
state: {
todos: [
{id: 1, text: 'React', status: 'active', editing: false},
{id: 2, text: 'Redux', status: 'active', editing: false},
{id: 3, text: 'Immutable', status: 'active', editing: false},
],
filter: 'all'
}
});
require('../node_modules/todomvc-app-css/index.css');
ReactDOM.render(
// We wrap our app in a Provider component to pass the store down to the components
<Provider store={store}>
<TodoAppContainer />
</Provider>,
document.getElementById('app')
);
如果你看看上面的代码段,你可以注意到我们的TodoApp组件实际是被TodoAppContainer代替.在Redux里,有两种类型的组件:展示组件和容器.我推荐你阅读一下由Dan Abramov(Redux的作者)写作的高信息量的文章,强调了展示组件和容器的差异性.
如果我想总结得快一点,我将引用Redux 文档的内容：
“展示组件是关于事件的样子(模板和样式),容器组件是关于事情是怎么工作的(数据获取,state更新)”.
所以我们创建store,传递给TodoAppContainer.然而为了子组件可以使用store,我们把state映射成为React组件TodoApp的props.
src/components/TodoApp.jsx
// ...
import {connect} from 'react-redux';
export class TodoApp extends React.Component {
// ...
}
function mapStateToProps(state) {
return {
todos: state.get('todos'),
filter: state.get('filter')
};
}
export const TodoAppContainer = connect(mapStateToProps)(TodoApp);
如果你在浏览器中重新加载app,你应该可以看到它初始化和之前一样,不过现在使用Redux tools.
Redux dev 工具
现在我们已经配置了redux store和reducer.我们可以配置Redux dev tools来展现数据流开发.
首先,获取Redux dev tools Chrome extension
dev tools可以在Store创建的时候可以加载.
src/index.jsx
// ...
import {compose, createStore} from 'redux';
const createStoreDevTools = compose(
window.devToolsExtension ? window.devToolsExtension() : f => f
)(createStore);
const store = createStoreDevTools(reducer);
// ...
Redux dev tools
重新加载app,点击Redux图标,有了.
有三个不同的监视器可以使用:Diff监视器,日志监视器,Slider监视器.
使用Action Creators配置我们的actions
切换item的不同状态.
下一步是允许用户在active和completed之前切换状态：
test/reducer_spec.js
import {List, Map, fromJS} from 'immutable';
import {expect} from 'chai';
import reducer from '../src/reducer';
describe('reducer', () => {
// ...
it('handles TOGGLE_COMPLETE by changing the status from active to completed', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
});
const action = {
type: 'TOGGLE_COMPLETE',
itemId: 1
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'completed'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
}));
});
it('handles TOGGLE_COMPLETE by changing the status from completed to active', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'completed'}
]
});
const action = {
type: 'TOGGLE_COMPLETE',
itemId: 3
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
{id: 3, text: 'Immutable', status: 'active'}
]
}));
});
});
为了通过这些测试,我们更新reducer:
src/reducer.js
// ...
function toggleComplete(state, itemId) {
// We find the index associated with the itemId
const itemIndex = state.get('todos').findIndex(
(item) => item.get('id') === itemId
);
// We update the todo at this index
const updatedItem = state.get('todos')
.get(itemIndex)
.update('status', status => status === 'active' ? 'completed' : 'active');
// We update the state to account for the modified todo
return state.update('todos', todos => todos.set(itemIndex, updatedItem));
}
export default function(state = Map(), action) {
switch (action.type) {
case 'SET_STATE':
return setState(state, action.state);
case 'TOGGLE_COMPLETE':
return toggleComplete(state, action.itemId);
}
return state;
}
和SET_STATE的action同一个地方,我们需要让TodoAppContainer组件感知到action,所以toggleComplete回调函数会被传递到TodoItem组件(实际调用函数的地方).
在Redux中,有标准的方法来做这件事：Action Creators.
action creators是简单的函数,返回合适的action，这些韩式是React的props的一些映射之一.
让我们创建第一个action creator:
src/action_creators.js
export function toggleComplete(itemId) {
return {
type: 'TOGGLE_COMPLETE',
itemId
}
}
现在,尽管TodoAppcontainer组件中的connect函数的调用可以用来获取store,我们告诉组件使用映射props的回调函数:
src/components/TodoApp.jsx
// ...
import * as actionCreators from '../action_creators';
export class TodoApp extends React.Component {
// ...
render() {
return <div>
// ...
// We use the spread operator for better lisibility
<TodoList {...this.props} />
// ...
</div>
}
};
export const TodoAppContainer = connect(mapStateToProps, actionCreators)(TodoApp);
重启你的webserver,刷新一下你的浏览器:当当.在条目上点击现在可以切换它的状态.如果你查看Redux dev tools,你可以看到触发的action和后继的更新.
改变目前的过滤器
现在每件事情都已经配置完毕,写其他的action是件小事.我们继续创建你希望的CHANGE_FILTERaction,改变当前state的filter,由此仅仅显示过滤过的条目.
开始创建action creator：
src/action_creators.js
// ...
export function changeFilter(filter) {
return {
type: 'CHANGE_FILTER',
filter
}
}
现在写reducer的单元测试:
test/reducer_spec.js
// ...
describe('reducer', () => {
// ...
it('handles CHANGE_FILTER by changing the filter', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
],
filter: 'all'
});
const action = {
type: 'CHANGE_FILTER',
filter: 'active'
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
],
filter: 'active'
}));
});
});
关联的reducer函数:
src/reducer.js
// ...
function changeFilter(state, filter) {
return state.set('filter', filter);
}
export default function(state = Map(), action) {
switch (action.type) {
case 'SET_STATE':
return setState(state, action.state);
case 'TOGGLE_COMPLETE':
return toggleComplete(state, action.itemId);
case 'CHANGE_FILTER':
return changeFilter(state, action.filter);
}
return state;
}
最后我们把changeFilter回调函数传递给TodoTools组件:
TodoApp.jsx
// ...
export class TodoApp extends React.Component {
// ...
render() {
return <div>
<section className="todoapp">
// ...
<TodoTools changeFilter={this.props.changeFilter}
filter={this.props.filter}
nbActiveItems={this.getNbActiveItems()} />
</section>
<Footer />
</div>
}
};
完成了,第一个filter selector工作完美
Item编辑
代码在这里
当用户编辑一个条目,实际上是两个actions触发的三个可能性:
- 用户输入编辑模式:
EDIT_ITEM - 用户退出编辑模式(不保存变化):
CANCEL_EDITING - 用户验证他的编辑(保存变化):
DONE_EDITING
我们可以为三个actions编写action creators：
src/action_creators.js
// ...
export function editItem(itemId) {
return {
type: 'EDIT_ITEM',
itemId
}
}
export function cancelEditing(itemId) {
return {
type: 'CANCEL_EDITING',
itemId
}
}
export function doneEditing(itemId, newText) {
return {
type: 'DONE_EDITING',
itemId,
newText
}
}
现在为这些actions编写单元测试:
test/reducer_spec.js
// ...
describe('reducer', () => {
// ...
it('handles EDIT_ITEM by setting editing to true', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active', editing: false},
]
});
const action = {
type: 'EDIT_ITEM',
itemId: 1
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active', editing: true},
]
}));
});
it('handles CANCEL_EDITING by setting editing to false', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active', editing: true},
]
});
const action = {
type: 'CANCEL_EDITING',
itemId: 1
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active', editing: false},
]
}));
});
it('handles DONE_EDITING by setting by updating the text', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active', editing: true},
]
});
const action = {
type: 'DONE_EDITING',
itemId: 1,
newText: 'Redux',
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'Redux', status: 'active', editing: false},
]
}));
});
});
现在我们可以开发reducer函数,实际操作三个actions:
src/reducer.js
function findItemIndex(state, itemId) {
return state.get('todos').findIndex(
(item) => item.get('id') === itemId
);
}
// We can refactor the toggleComplete function to use findItemIndex
function toggleComplete(state, itemId) {
const itemIndex = findItemIndex(state, itemId);
const updatedItem = state.get('todos')
.get(itemIndex)
.update('status', status => status === 'active' ? 'completed' : 'active');
return state.update('todos', todos => todos.set(itemIndex, updatedItem));
}
function editItem(state, itemId) {
const itemIndex = findItemIndex(state, itemId);
const updatedItem = state.get('todos')
.get(itemIndex)
.set('editing', true);
return state.update('todos', todos => todos.set(itemIndex, updatedItem));
}
function cancelEditing(state, itemId) {
const itemIndex = findItemIndex(state, itemId);
const updatedItem = state.get('todos')
.get(itemIndex)
.set('editing', false);
return state.update('todos', todos => todos.set(itemIndex, updatedItem));
}
function doneEditing(state, itemId, newText) {
const itemIndex = findItemIndex(state, itemId);
const updatedItem = state.get('todos')
.get(itemIndex)
.set('editing', false)
.set('text', newText);
return state.update('todos', todos => todos.set(itemIndex, updatedItem));
}
export default function(state = Map(), action) {
switch (action.type) {
// ...
case 'EDIT_ITEM':
return editItem(state, action.itemId);
case 'CANCEL_EDITING':
return cancelEditing(state, action.itemId);
case 'DONE_EDITING':
return doneEditing(state, action.itemId, action.newText);
}
return state;
}
清除完成,添加和删除条目
三个剩下的action是:
-
CLEAR_COMPLETED,在TodoTools组件中触发,从列表中清除完成的条目 -
ADD_ITEM,在TodoHeader中触发,根据用户的的输入文本来添加条目 -
DELETE_ITEM,相似TodoItem中调用,删除一个条目
我们现在使用的工作流是:添加action creators,单元测试reducer和代码逻辑,最终通过props传递回调函数:
src/action_creators.js
// ...
export function clearCompleted() {
return {
type: 'CLEAR_COMPLETED'
}
}
export function addItem(text) {
return {
type: 'ADD_ITEM',
text
}
}
export function deleteItem(itemId) {
return {
type: 'DELETE_ITEM',
itemId
}
}
test/reducer_spec.js
// ...
describe('reducer', () => {
// ...
it('handles CLEAR_COMPLETED by removing all the completed items', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'completed'},
]
});
const action = {
type: 'CLEAR_COMPLETED'
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
]
}));
});
it('handles ADD_ITEM by adding the item', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'}
]
});
const action = {
type: 'ADD_ITEM',
text: 'Redux'
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'active'},
]
}));
});
it('handles DELETE_ITEM by removing the item', () => {
const initialState = fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
{id: 2, text: 'Redux', status: 'completed'},
]
});
const action = {
type: 'DELETE_ITEM',
itemId: 2
}
const nextState = reducer(initialState, action);
expect(nextState).to.equal(fromJS({
todos: [
{id: 1, text: 'React', status: 'active'},
]
}));
});
});
src/reducer.js
function clearCompleted(state) {
return state.update('todos',
(todos) => todos.filterNot(
(item) => item.get('status') === 'completed'
)
);
}
function addItem(state, text) {
const itemId = state.get('todos').reduce((maxId, item) => Math.max(maxId,item.get('id')), 0) + 1;
const newItem = Map({id: itemId, text: text, status: 'active'});
return state.update('todos', (todos) => todos.push(newItem));
}
function deleteItem(state, itemId) {
return state.update('todos',
(todos) => todos.filterNot(
(item) => item.get('id') === itemId
)
);
}
export default function(state = Map(), action) {
switch (action.type) {
// ...
case 'CLEAR_COMPLETED':
return clearCompleted(state);
case 'ADD_ITEM':
return addItem(state, action.text);
case 'DELETE_ITEM':
return deleteItem(state, action.itemId);
}
return state;
}
src/components/TodoApp.jsx
// ...
export class TodoApp extends React.Component {
// ...
render() {
return <div>
<section className="todoapp">
// We pass down the addItem callback
<TodoHeader addItem={this.props.addItem}/>
<TodoList {...this.props} />
// We pass down the clearCompleted callback
<TodoTools changeFilter={this.props.changeFilter}
filter={this.props.filter}
nbActiveItems={this.getNbActiveItems()}
clearCompleted={this.props.clearCompleted}/>
</section>
<Footer />
</div>
}
};
我们的TodoMVC app现在完成了.
包装起来
这我们的测试驱动的React,Redux&Immutable 技术栈
如果你想了解更多内容,有更多的事情等着你去挖掘
例如:
