使用Pinia

npm install pinia

store文件里index.js

import { createPinia } from 'pinia'

const pinia = createPinia()

export default pinia

main.js导入并引用

import { createApp } from 'vue'
import App from './App.vue'
import pinia from './stores'

createApp(App).use(pinia).mount('#app')

pinia的状态管理，不同状态可以区分不同文件

//定义关于counter的store
import { defineStore } from ‘pinia’

//defineStore 是返回一个函数 函数命名最好有use前缀，根据函数来进行下一步操作
const useCounter = defineStore('counter',{
	state: () => {
		count:99
	}
})

export default useCounter

调用pinia，获取pinia状态值，导入Counter.js,获取Counter.js里面state.count

<template>
  <div class="home">
    <h2>Home View</h2>
    <h2>count: {{ counterStore.count }}</h2>
  </div>
</template>

<script setup>
  import useCounter from '@/stores/counter';

  const counterStore = useCounter()

</script>

<style scoped>
</style>

注意：pinia解构出来的state也是可以调用，但会失去响应式，需要toRef或者pinia自带storeToRefs

<template>
  <div class="home">
    <h2>Home View</h2>
    <h2>count: {{ counterStore.count }}</h2>
    <h2>count: {{ count }}</h2>
    <button @click="incrementCount">count+1</button>
  </div>
</template>

<script setup>
  import { toRefs } from 'vue'
  import { storeToRefs } from 'pinia'
  import useCounter from '@/stores/counter';

  const counterStore = useCounter()

  // const { count } = toRefs(counterStore)
  const { count } = storeToRefs(counterStore)


  function incrementCount() {
    counterStore.count++
  }

</script>

<style scoped>
</style>

store的核心部分：state，getter，action
（相当于：data、computed、methods）

State

读取和写入state：

const counterStore = useCounter()

counterStore.counter++
counterStore.name = 'coderWhy'

重置State reset

const counterStore = useCounter()
conterStore.$reset()

改变State patch

const counterStore = useCounter()

counterStore.$patch({
	counter:100,
	name:'kobe'
})

替换State

conterStore.$state = {
	counter:1,
	name:'why'
}

Getters

Getters相当于Store的计算属性computed：

用defineStore()中的getters属性定义
getters中可以定义接受一个state作为参数的函数

expoer const useCounter = defineStore('counter',{
	state: () => {
		counter:100,
		firstname:'kobe'
	},
	getters:{
		doubleCounter(state){
			return state.counter *2
		}
	}
})

访问当前Store里getters方法

const counterSotre = useCounter()
console.log(counterStore.doublCounter)

使用this来访问当前的store实例中getters

expoer const useCounter = defineStore('counter',{
	state: () => {
		counter:100,
		firstname:'kobe'
	},
	getters:{
		doubleCounter(state){
			return state.counter *2
		}
		doubleCounterAdd(){
			//this指向store
			return this.doubleCounter +1 
		}
	}
})

访问其它store的getters

import useUser from ./user

const userStore = useUser()

expoer const useCounter = defineStore('counter',{
	state: () => {
		counter:100,
		firstname:'kobe'
	},
	getters:{
	//调用其它Store
		doubleCounterUser(){
			return this.doubleCounter + userStore.umu
		}
	}
})

通过getters可以返回一个函数，可以传参数

expoer const useCounter = defineStore('counter',{
	state: () => {
		counter:100,
		firstname:'kobe'
	},
	getters:{
	//调用其它Store
		doubleCounter(state){
			return function (is) {
				return state.id + id
			}
		}
	}
})

const StoreConter = useCounter();
//传参
StoreCounter.doublCounter(111)

Actions

Actions 相当于组件中的methods，可以使用defineStore()中的actions属性定义
和getters一样，在action中可以通过this访问整个store实例：

expoer const useCounter = defineStore('counter',{
	state: () => {
		counter:100,
		firstname:'kobe'
	},
	getters:{
		//调用其它Store
		doubleCounter(state){
			return function (is) {
				return state.id + id
			}
		}
	},
	actions:{
		increment(){
			this.counter++
		},
		//传参
		incrementnum(num){
			this.counter += num
		}
	}
})

Actions执行异步操作 await

actions:{
	async fetchHome(){
		//请求
		const res = await fetch('?????')
		const data = await res.json()
		console.log('data',data)
		return data
	}
}

cosnt counterStore = useCounter

counterStore.fetchHome().then(res => {
	console.log(res)
})

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Vue3-Pinia的基本使用