大前端 - react -Mobx6(数据流)

代码地址:

1.mobx概述

mobx是什么?mobox是状态管理库。和redux做的事情一样,但是比redux简单。
没有那么多的模版代码。

目前最新版本为 6,版本 4 和版本 5 已不再支持。

在 MobX 6 中不推荐使用装饰器语法,因为它不是 ES 标准,并且标准化过程要花费很长时间,但是通过配置仍然可以启用装饰器语法。

MobX 可以运行在任何支持 ES5 的环境中,包含浏览器和 Node。

MobX 通常和 React 配合使用,但是在 Angular 和 Vue 中也可以使用 MobX。

02-mobx中的核心概念

核心概念

  1. observable:被 MobX 跟踪的状态。
  2. action:允许修改状态的方法,在严格模式下只有 action 方法被允许修改状态。
  3. computed:根据现有状态衍生出来的状态。
  4. flow:执行副作用,它是 generator 函数。可以更改状态值。

3. 工作流程

在这里插入图片描述
工作流程文字描述:
在视图中,通过触发事件,调用actions方法,当调用actions 方法之后,才会去更新状态,当这个状态更新完成之后会去更新基于这个状态的派生状态,派生状态更新完成之后,就会去更新视图了。这就是它的工作流程。

4. 下载

  • mobx:MobX 核心库
  • mobx-react-lite:仅支持函数组件
  • mobx-react:既支持函数组件也支持类组件

yarn add [email protected] [email protected]

5. 案例:驱动之计数器

在组件中显示数值状态,单击[+1]按钮使数值加一,单击[-1]按钮使数值减一。

  1. 创建用于存储状态的 Store
export default class CounterStore{
	constructor() {
		this.count = 0
	}
} 
  1. 创建用于修改状态的方法
export default class CounterStore{
	constructor() {
		this.count = 0
	}
	increment() {
		this.count + =1
	}
	decrement() {
		this.count -=1
	}
	
} 
  1. 让 MobX 可以追踪状态的变化
  • 3.1. 通过 observable 标识状态,使状态可观察
  • 3.2 通过 action 标识修改状态的方法,状态只有通过 action 方法修改后才会通知视图更新

// makeObservable: 
// 第一个参数是this,这个this指的是当前类的实例对象。 
// 第2个参数:配置对象。在这个对象中可以指定哪些是属性,哪些是状态。
import { action, makeObservable, observable } from "mobx"
   
export default class CounterStore {
   constructor() {
     this.count = 0
     makeObservable(this, {

       // 标记为状态
       count: observable,
 
       // 标记为更改状态的方法
       increment: action,
       decrement: action
     })
   }
   increment() {
     this.count += 1
   }
   decrement() {
     this.count -= 1
   }
 }
  1. 创建 Store 类的实例对象并将实例对象传递给组件
// App.js
import Counter from "./Counter"
import CounterStore from "../store/Counter"

const counterStore = new CounterStore()

function App() {
 return <Counter counterStore={counterStore} />
}

export default App
  1. 在组件中通过 Store 实例对象获取状态以及操作状态的方法
   function Counter({ counterStore }) {
     return (
       <Container>
         <Button onClick={() => counterStore.increment()}>
           INCREMENT
         </Button>
         <Button>{counterStore.count}</Button>
         <Button onClick={() => counterStore.decrement()}>
           DECREMENT
         </Button>
       </Container>
     )
   }
   
   export default Counter
  1. 当组件中使用到的 MobX 管理的状态发生变化后,使视图更新。通过 observer 方法包裹组件实现目的
   import { observer } from "mobx-react-lite"
   
   function Counter() { }
   
   export default observer(Counter)
  1. 简化组件代码(会报错,因为this指向问题)
 function Counter({ counterStore }) {
     const { count, increment, decrement } = counterStore
     return (
       <Container>
         <Button border="left" onClick={increment}>
           INCREMENT
         </Button>
         <Button>{count}</Button>
         <Button border="right" onClick={decrement}>
           DECREMENT
         </Button>
       </Container>
     )
   }
  1. 当代码简化后,修改状态的方法中的 this 指向出现了问题,通过 action.bound 强制绑定 this,使 this 指向 Store 实例对象
import { action, makeObservable, observable } from "mobx"
   
export default class CounterStore {
  constructor() {
    this.count = 0
    makeObservable(this, {
      // 标记为状态
      count: observable,

      // 标记为action
      increment: action.bound,
      decrement: action.bound
    })
  }
  increment() {
    this.count += 1
  }
  decrement() {
    this.count -= 1
  }
}
  1. 总结:状态变化更新视图的必要条件

    1. 状态必须被标记为 observable
    2. 更改状态的方法必须被标记为 action
    3. 组件必须通过 observer 方法包裹
  2. 创建RootStore实现全局状态共享
    1.在应用中可存在多个 Store,多个 Store 最终要通过 RootStore 管理,在每个组件都需要获取到 RootStore。
    2.实现全局状态共享

// store/index.js
    import { createContext, useContext } from "react"
    import CounterStore from "./Counter"
    
    class RootStore {
      constructor() {
        this.counterStore = new CounterStore()
      }
    }
    const rootStore = new RootStore()
    const RootStoreContext = createContext()
    
    export const RootStoreProvider = ({ children }) => {
      return (
        <RootStoreContext.Provider value={rootStore}>
          {children}
        </RootStoreContext.Provider>
      )
    }
    
    export const useRootStore = () => {
      return useContext(RootStoreContext)
    }
   // App.js
    import { RootStoreProvider } from "../store"
    import Counter from "./Counter"
    
    function App() {
      return (
        <RootStoreProvider>
          <Counter />
        </RootStoreProvider>
      )
    }
    
    export default App
// Counter.js
  import { observer } from "mobx-react-lite"
    import { useRootStore } from "../store"
    
    function Counter() {
      const { counterStore } = useRootStore()
      const { count, increment, decrement } = counterStore
      return (
        <Container>
          <Button onClick={increment}>
            INCREMENT
          </Button>
          <Button>{count}</Button>
          <Button onClick={decrement}>
            DECREMENT
          </Button>
        </Container>
      )
    }
    // 数据变化重新渲染组件
    export default observer(Counter)

6. 案例驱动之 Todo

6.1 创建 Store
  1. 创建用于管理 Todo 任务的 Store

    import { makeObservable, observable } from "mobx"
    
    export default class Todo {
      constructor(todo) {
        this.id = todo.id
        this.title = todo.title
        this.isCompleted = todo.isCompleted || false
        this.isEditing = false
        makeObservable(this, {
          title: observable,
          isCompleted: observable,
          isEditing: observable
        })
      }
    }
    
  2. 创建用于管理 Todo 任务列表的 Store

    import { makeObservable, observable } from "mobx"
    
    export default class TodoStore {
      constructor() {
        this.todos = []
        makeObservable(this, {
          todos: observable
        })
      }
    }
    
6.2 添加任务
  1. 创建向 todo 任务列表中添加 todo 任务的方法

    import { action, makeObservable, observable } from "mobx"
    import Todo from "./Todo"
    
    export default class TodoStore {
      constructor() {
        this.todos = []
        makeObservable(this, {
          todos: observable,
          addTodo: action.bound
        })
      }
      addTodo(title) {
        this.todos.push(new Todo({ title, id: this.generateTodoId() }))
      }
      generateTodoId() {
        if (!this.todos.length) return 1
        return this.todos.reduce((id, todo) => (id < todo.id ? todo.id : id), 0) + 1
      }
    }
    
  2. 在组件中实现添加任务的逻辑

    import { useState } from "react"
    import { useRootStore } from "../../store"
    
    function Header() {
      const [title, setTitle] = useState("")
      const { todoStore } = useRootStore()
      const { addTodo } = todoStore
      return (
        <header className="header">
          <input
            value={title}
            onChange={e => setTitle(e.target.value)}
            onKeyUp={e => {
              if (e.key !== "Enter") return
              addTodo(title)
              setTitle("")
            }}
          />
        </header>
      )
    }
    
    export default Header
    
6.3 显示任务列表
import { observer } from "mobx-react-lite"
import { useRootStore } from "../../store"
import Todo from "./Todo"

function Main() {
  const { todoStore } = useRootStore()
  const { todos } = todoStore
  return (
    <section className="main">
      <ul className="todo-list">
        {todos.map(todo => (
          <Todo key={todo.id} todo={todo} />
        ))}
      </ul>
    </section>
  )
}

export default observer(Main)
function Todo({ todo }) {
  return (
    <li>
      <div className="view">
        <input className="toggle" type="checkbox" />
        <label>{todo.title}</label>
        <button className="destroy" />
      </div>
      <input className="edit" />
    </li>
  )
}

export default Todo
6.4 加载远端任务
  1. 下载 json-server:yarn add [email protected]

  2. 创建 db.json

    {
      "todos": [
        {
          "id": 1,
          "title": "吃饭",
          "isCompleted": false
        },
        {
          "id": 2,
          "title": "睡觉",
          "isCompleted": false
        },
        {
          "id": 3,
          "title": "打豆豆",
          "isCompleted": false
        }
      ]
    }
    
  3. 在 package.json 文件中添加启动命令

    "scripts": {
        "json-server": "json-server --watch ./db.json --port 3001"
      }
    
  4. 启动 json-server:npm run json-server

  5. 在 todoStore 中添加加载任务列表的方法

    import axios from "axios"
    import { flow, makeObservable, observable } from "mobx"
    import Todo from "./Todo"
    
    export default class TodoStore {
      constructor() {
        this.todos = []
        makeObservable(this, {
          todos: observable,
          loadTodos: flow
        })
        this.loadTodos()
      }
      *loadTodos() {
        let response = yield axios.get("http://localhost:3001/todos")
        response.data.forEach(todo => this.todos.push(new Todo(todo)))
      }
    }
    
6.5 更改任务状态
  1. 在 Todo 类中添加修改任务是否已经完成的方法

    export default class Todo {
      constructor() {
        makeObservable(this, {
          modifyTodoIsCompleted: action.bound
        })
      }
      modifyTodoIsCompleted() {
        this.isCompleted = !this.isCompleted
      }
    }
    
  2. 创建 TodoCompleted 组件实现逻辑

    import { observer } from "mobx-react-lite"
    
    function TodoCompleted({ todo }) {
      const { isCompleted, modifyTodoIsCompleted } = todo
      return (
        <input
          className="toggle"
          type="checkbox"
          checked={isCompleted}
          onChange={modifyTodoIsCompleted}
        />
      )
    }
    
    export default observer(TodoCompleted)
    
  3. Todo 组件中引用TodoCompleted 组件并根据条件决定是否为 li 添加 completed 类名

    import { observer } from "mobx-react-lite"
    import TodoCompleted from "./TodoCompleted"
    
    function Todo({ todo }) {
      return (
        <li className={todo.isCompleted ? "completed" : ""}>
          <div className="view">
            <TodoCompleted todo={todo} />
          </div>
        </li>
      )
    }
    
    export default observer(Todo)
    
6.6 删除任务
  1. todoStore 中添加实现删除任务的方法

    import axios from "axios"
    import { action, makeObservable,  } from "mobx"
    
    export default class TodoStore {
      constructor() {
        makeObservable(this, {
          removeTodo: action.bound
        })
      }
      removeTodo(id) {
        this.todos = this.todos.filter(todo => todo.id !== id)
      }
    }
    
  2. 创建 TodoDelete 组件实现删除 todo 任务逻辑

    import { useRootStore } from "../../store"
    
    function TodoDelete({ id }) {
      const { todoStore } = useRootStore()
      const { removeTodo } = todoStore
      return <button className="destroy" onClick={removeTodo.bind(null, id)} />
    }
    
    export default TodoDelete
    
  3. Todo 组件调用 TodoDelete 组件并传入 todo ID

    import { observer } from "mobx-react-lite"
    import TodoDelete from "./TodoDelete"
    
    function Todo({ todo }) {
      return (
        <li>
          <div className="view">
            <TodoDelete id={todo.id} />
          </div>
        </li>
      )
    }
    
    export default observer(Todo)
    
6.7 编辑任务
  1. 在 todoStore 中添加更改任务是否处于编辑状态的方法

    import { action, makeObservable } from "mobx"
    
    export default class Todo {
      constructor(todo) {
        makeObservable(this, {
          modifyTodoIsEditing: action.bound,
        })
      }
      modifyTodoIsEditing() {
        this.isEditing = !this.isEditing
      }
    }
    
  2. 添加 TodoTitle 组件展示任务标题并为其添加双击事件,当事件发生时将任务更改为可编辑状态

    function TodoTitle({ todo }) {
      const { title, modifyTodoIsEditing } = todo
      return <label onDoubleClick={modifyTodoIsEditing}>{title}</label>
    }
    
    export default TodoTitle
    
  3. Todo 组件中调用 TodoTitle 组件,并为 li 添加 editing 类名

    import { observer } from "mobx-react-lite"
    import TodoTitle from "./TodoTitle"
    import classnames from "classnames"
    
    function Todo({ todo }) {
      return (
        <li className={classnames({ completed: todo.isCompleted, editing: todo.isEditing })} >
          <div className="view">
            <TodoTitle todo={todo} />
          </div>
        </li>
      )
    }
    
    export default observer(Todo)
    
  4. 创建 TodoEditing 组件实现编辑 todo 任务标题

    import { useRef, useEffect } from "react"
    
    function TodoEditing({ todo }) {
      const { title, modifyTodoTitle, isEditing } = todo
      const ref = useRef(null)
      useEffect(() => {
        if (isEditing) ref.current.focus()
      }, [isEditing])
      return (
        <input
          ref={ref}
          className="edit"
          defaultValue={title}
          onBlur={e => modifyTodoTitle(e.target.value)}
        />
      )
    }
    
    export default TodoEditing
    
  5. Todo 组件中调用 TodoEditing 组件并传递 todo 任务

    import { observer } from "mobx-react-lite"
    import TodoTitle from "./TodoTitle"
    import classnames from "classnames"
    import TodoEditing from "./TodoEditing"
    
    function Todo({ todo }) {
      return (
        <li className={classnames({ completed: todo.isCompleted, editing: todo.isEditing })} >
          <div className="view">
            <TodoTitle todo={todo} />
          </div>
          <TodoEditing todo={todo} />
        </li>
      )
    }
    
    export default observer(Todo)
    
6.8 计算未完成任务数量
  1. 在 todoStore 中添加获取未完成任务数量的派生状态

    import axios from "axios"
    import { makeObservable, computed } from "mobx"
    
    export default class TodoStore {
      constructor() {
        makeObservable(this, {
          unCompletedTodoCount: computed
        })
      }
      // 派生状态
      get unCompletedTodoCount() {
        return this.todos.filter(todo => !todo.isCompleted).length
      }
    }
    
  2. 创建 UnCompletedTodoCount 组件实现逻辑

    import { observer } from "mobx-react-lite"
    import { useRootStore } from "../../store"
    
    function UnCompletedTodoCount() {
      const { todoStore } = useRootStore()
      const { unCompletedTodoCount } = todoStore
      return (
        <span className="todo-count">
          <strong>{unCompletedTodoCount}</strong> item left
        </span>
      )
    }
    
    export default observer(UnCompletedTodoCount)
    
  3. Footer 组件中调用 UnCompletedTodoCount 组件

    import UnCompletedTodoCount from "./UnCompletedTodoCount"
    
    function Footer() {
      return (
        <footer className="footer">
          <UnCompletedTodoCount />
        </footer>
      )
    }
    
    export default Footer
    
6.9 任务过滤
  1. todoStore 中添加存储过滤条件的属性以及更改过滤条件的方法

    import axios from "axios"
    import { action, makeObservable, observable, } from "mobx"
    
    export default class TodoStore {
      constructor() {
        this.filterCondition = "All"
        makeObservable(this, {
          modifyFilterCondition: action.bound,
          filterCondition: observable,
        })
      }
      modifyFilterCondition(filterCondition) {
        this.filterCondition = filterCondition
      }
    }
    
  2. 创建 TodoFilter 组件,为过滤按钮添加事件以更改过滤条件,根据过滤条件为按钮添加 selected 类名

    import classNames from "classnames"
    import { observer } from "mobx-react-lite"
    import { useRootStore } from "../../store"
    
    function TodoFilter() {
      const { todoStore } = useRootStore()
      const { filterCondition, modifyFilterCondition } = todoStore
      return (
        <ul className="filters">
          <li>
            <button
              onClick={() => modifyFilterCondition("All")}
              className={classNames({ selected: filterCondition === "All" })}
            >
              All
            </button>
          </li>
          <li>
            <button
              onClick={() => modifyFilterCondition("Active")}
              className={classNames({ selected: filterCondition === "Active" })}
            >
              Active
            </button>
          </li>
          <li>
            <button
              onClick={() => modifyFilterCondition("Completed")}
              className={classNames({ selected: filterCondition === "Completed" })}
            >
              Completed
            </button>
          </li>
        </ul>
      )
    }
    
    export default observer(TodoFilter)
    
  3. Footer 组件中调用 TodoFilter 组件

    import TodoFilter from "./TodoFilter"
    
    function Footer() {
      return (
        <footer className="footer">
          <TodoFilter />
        </footer>
      )
    }
    
    export default Footer
    
  4. TodoStore 中添加派生状态,根据条件获取过滤后的 todo 列表

    import axios from "axios"
    import { action, flow, makeObservable, observable, computed } from "mobx"
    import Todo from "./Todo"
    
    export default class TodoStore {
      constructor() {
        makeObservable(this, {
          filterTodos: computed
        })
      }
      get filterTodos() {
        switch (this.filterCondition) {
          case "Active":
            return this.todos.filter(todo => !todo.isCompleted)
          case "Completed":
            return this.todos.filter(todo => todo.isCompleted)
          default:
            return this.todos
        }
      }
    }
    
  5. 在 Main 组件获取 filterTodos 派生状态

    import { observer } from "mobx-react-lite"
    import { useRootStore } from "../../store"
    import Todo from "./Todo"
    
    function Main() {
      const { todoStore } = useRootStore()
      const { filterTodos } = todoStore
      return (
        <section className="main">
          <ul className="todo-list">
            {filterTodos.map(todo => (
              <Todo key={todo.id} todo={todo} />
            ))}
          </ul>
        </section>
      )
    }
    
    export default observer(Main)
    
6.10 清除已完成任务
  1. TodoStore 中添加清除已完成任务的方法

    import axios from "axios"
    import { action, makeObservable, } from "mobx"
    
    export default class TodoStore {
      constructor() {
        makeObservable(this, {
          clearCompleted: action.bound
        })
      }
      clearCompleted() {
        this.todos = this.todos.filter(todo => !todo.isCompleted)
      }
    }
    
  2. 创建 ClearCompleted 组件实现清除已完成任务功能

    import { useRootStore } from "../../store"
    
    function ClearCompleted() {
      const { todoStore } = useRootStore()
      const { clearCompleted } = todoStore
      return (
        <button className="clear-completed" onClick={clearCompleted}>
          Clear completed
        </button>
      )
    }
    
    export default ClearCompleted
    
  3. Footer 组件中调用 ClearCompleted 组件

    import ClearCompleted from "./ClearCompleted"
    
    function Footer() {
      return (
        <footer className="footer">
          <ClearCompleted />
        </footer>
      )
    }
    
    export default Footer
    

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