書籍完整目錄

3.2 Redux TodoApp

上一節講完了 redux 中的概念，但是仍然沒有和 react 聯繫起來，這一節
將利用 redux 在 react 中實現完整的 todolist：

• 在 react 使用 redux

• 通過 Provider 連接 react 和 redux store

• 創建 action creators

• 創建 reducer

• 創建 Container Component

• 牀架 Dummy Component

3.2.1 在 react 使用 redux

redux 可以和很多第三方的框架結合起來使用，為了在 react 中使用 redux，可以通過 react-redux

安裝 react-redux

$ npm install --save react-redux

3.2.2 通過 Provider 連接 react 和 redux store

react-redux 提供了一個叫 Provider 的組件，將 react 和 react-redux 結合的方式是用 Provider 嵌套應用的 App 組件，並將 redux store 作為屬性傳遞到 Provider 組件之中。

index.js

import React from 'react'
import { render } from 'react-dom'
import { Provider } from 'react-redux'
import { createStore } from 'redux'
import todoApp from './reducers'
import App from './components/App'

/** store 數據結構 sample
{
  visibilityFilter: 'SHOW_ALL',
  todos: [
    {
      text: 'Consider using Redux',
      completed: true,
    },
    {
      text: 'Keep all state in a single tree',
      completed: false
    }
  ]
}
*/
let store = createStore(todoApp)

render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root')
)

這裏使用到了 React 的 Context ，App 下面的所有組件可以利用 context 獲取傳入到 Provider 中的 store

3.2.3 創建 action creators

actions/index.js

let nextTodoId = 0
export const addTodo = (text) => {
  return {
    type: 'ADD_TODO',
    id: nextTodoId++,
    text
  }
}

export const setVisibilityFilter = (filter) => {
  return {
    type: 'SET_VISIBILITY_FILTER',
    filter
  }
}

export const toggleTodo = (id) => {
  return {
    type: 'TOGGLE_TODO',
    id
  }
}

3.2.4 創建 reducer

首先創建根 reducer ,通過 redux.combineReducers 方法將其他 reducer 結合起來，每個數據 key 都需要實現一個對應的 reducer

reducer/index.js

import { combineReducers } from 'redux'
import todos from './todos'
import visibilityFilter from './visibilityFilter'

const todoApp = combineReducers({
  todos,
  visibilityFilter
})

export default todoApp

接着是 todos reducer , 需要注意的地方是其中使用 Object.assign 方法保證每次都是返回新的
對象

reducer/todos.js

const todo = (state, action) => {
  switch (action.type) {
    case 'ADD_TODO':
      return {
        id: action.id,
        text: action.text,
        completed: false
      }
    case 'TOGGLE_TODO':
      if (state.id !== action.id) {
        return state
      }

      return Object.assign({}, state, {
        completed: !state.completed
      })

    default:
      return state
  }
}

const todos = (state = [], action) => {
  switch (action.type) {
    case 'ADD_TODO':
      return [
        ...state,
        todo(undefined, action)
      ]
    case 'TOGGLE_TODO':
      return state.map(t =>
        todo(t, action)
      )
    default:
      return state
  }
}

export default todos

最後是 visibilityFilter

reducers/visibibityFilter.js

const visibilityFilter = (state = 'SHOW_ALL', action) => {
  switch (action.type) {
    case 'SET_VISIBILITY_FILTER':
      return action.filter
    default:
      return state
  }
}

export default visibilityFilter

3.2.5 Container Component

在介紹 flux 的時候介紹過組件分兩個類型，smart component 和 dummy component，在 redux 中 Container Component 就是 smart component

作用

在 react 應用中，store 的數據只有 container component 能知曉，container component 會將知曉的數據傳遞給 dummy components ，除此之外 action 的觸發方法也會由它傳遞給 dummy components

connect 方法

react-redux 提供了一個叫 connect 的方法，可以將一個組件變為 container component

const ContainerComponent = connect(
    /**
     * 方法將 store 作為參數，返回有個 {key: Value} 對象，key 作為屬性傳遞給 DummyComponent 
     * @type {[type]}
     */
    mapStateToProps: Function,
    /**
     * 方法傳遞 store.dispatch 作為參數，返回一個{key: Function} 對象，key 作為屬性傳遞給 DummyComponent 
     * @type {[type]}
     */
    mapDispatchToProps: Function
)(DummyComponent)

其本質就是獲取react context 中的 store，並將 store 中的數據作為屬性傳遞到原來的組件中

創建 todolist 的 container component

todolist 會分為三個 container，有個負責 todolist，一個負責 filter，一個為添加 todo，首先是 todolist。

containers/VisibleTodoList.js

import { connect } from 'react-redux'
import { toggleTodo } from '../actions'
import TodoList from '../components/TodoList'

const getVisibleTodos = (todos, filter) => {
  switch (filter) {
    case 'SHOW_ALL':
      return todos
    case 'SHOW_COMPLETED':
      return todos.filter(t => t.completed)
    case 'SHOW_ACTIVE':
      return todos.filter(t => !t.completed)
  }
}

const mapStateToProps = (state) => {
  return {
    todos: getVisibleTodos(state.todos, state.visibilityFilter)
  }
}

const mapDispatchToProps = (dispatch) => {
  return {
    onTodoClick: (id) => {
      dispatch(toggleTodo(id))
    }
  }
}

const VisibleTodoList = connect(
  mapStateToProps,
  mapDispatchToProps
)(TodoList)

export default VisibleTodoList

containers/FilterLink.js

import { connect } from 'react-redux'
import { setVisibilityFilter } from '../actions'
import Link from '../components/Link'

const mapStateToProps = (state, ownProps) => {
  return {
    active: ownProps.filter === state.visibilityFilter
  }
}

const mapDispatchToProps = (dispatch, ownProps) => {
  return {
    onClick: () => {
      dispatch(setVisibilityFilter(ownProps.filter))
    }
  }
}

const FilterLink = connect(
  mapStateToProps,
  mapDispatchToProps
)(Link)

export default FilterLink

containers/AddTodo.js

import React from 'react'
import { connect } from 'react-redux'
import { addTodo } from '../actions'

let AddTodo = ({ dispatch }) => {
  let input

  return (
    <div>
      <form onSubmit={e => {
        e.preventDefault()
        if (!input.value.trim()) {
          return
        }
        dispatch(addTodo(input.value))
        input.value = ''
      }}>
        <input ref={node => {
          input = node
        }} />
        <button type="submit">
          Add Todo
        </button>
      </form>
    </div>
  )
}
AddTodo = connect()(AddTodo)

export default AddTodo

3.2.6 負者展現的 Dummy Components

components/App.js: App.js 連接所有的 Container Components

import React from 'react'
import Footer from './Footer'
import AddTodo from '../containers/AddTodo'
import VisibleTodoList from '../containers/VisibleTodoList'

const App = () => (
  <div>
    <AddTodo />
    <VisibleTodoList />
    <Footer />
  </div>
)

export default App

components/TodoList.js: 展現 todos 列表

import React, { PropTypes } from 'react'
import Todo from './Todo'

const TodoList = ({ todos, onTodoClick }) => (
  <ul>
    {todos.map(todo =>
      <Todo
        key={todo.id}
        {...todo}
        onClick={() => onTodoClick(todo.id)}
      />
    )}
  </ul>
)

TodoList.propTypes = {
  todos: PropTypes.arrayOf(PropTypes.shape({
    id: PropTypes.number.isRequired,
    completed: PropTypes.bool.isRequired,
    text: PropTypes.string.isRequired
  }).isRequired).isRequired,
  onTodoClick: PropTypes.func.isRequired
}

export default TodoList

components/Todo.js

import React, { PropTypes } from 'react'

const Todo = ({ onClick, completed, text }) => (
  <li
    onClick={onClick}
    style={{
      textDecoration: completed ? 'line-through' : 'none'
    }}
  >
    {text}
  </li>
)

Todo.propTypes = {
  onClick: PropTypes.func.isRequired,
  completed: PropTypes.bool.isRequired,
  text: PropTypes.string.isRequired
}

export default Todo

components/Link.js

import React, { PropTypes } from 'react'

const Link = ({ active, children, onClick }) => {
  if (active) {
    return <span>{children}</span>
  }

  return (
    <a href="#"
       onClick={e => {
         e.preventDefault()
         onClick()
       }}
    >
      {children}
    </a>
  )
}

Link.propTypes = {
  active: PropTypes.bool.isRequired,
  children: PropTypes.node.isRequired,
  onClick: PropTypes.func.isRequired
}

export default Link

components/Footer.js

import React from 'react'
import FilterLink from '../containers/FilterLink'

const Footer = () => (
  <p>
    Show:
    {" "}
    <FilterLink filter="SHOW_ALL">
      All
    </FilterLink>
    {", "}
    <FilterLink filter="SHOW_ACTIVE">
      Active
    </FilterLink>
    {", "}
    <FilterLink filter="SHOW_COMPLETED">
      Completed
    </FilterLink>
  </p>
)

export default Footer