[vue3] pinia的基本使用

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storereturn this.doubleCounter +1 }}
})

访问其它store的getters

import useUser from ./userconst userStore = useUser()expoer const useCounter = defineStore('counter',{state: () => {counter:100,firstname:'kobe'},getters:{//调用其它StoredoubleCounterUser(){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StoredoubleCounter(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StoredoubleCounter(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 = useCountercounterStore.fetchHome().then(res => {console.log(res)
})

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Vue3-Pinia的基本使用