Vue生态的新成员Pinia的详细介绍

yarn add pinia@next
# 或者 使用npm
npm install pinia@next

//main.js
import { createApp } from 'vue'
import App from './App.vue'
import router from './router'
import { createPinia } from 'pinia'

createApp(App)
  .use(router)
  .use(createPinia())
  .mount('#app')

// store/loggedInUser.js
import { defineStore } from 'pinia'

export const useLoggedInUserStore = defineStore({
// id 是必填的，并且所有 Store 中唯一。因为Pinia会将它在devtools显示
  id: 'loggedInUser',
  state () {
    return {
      name: '太凉',
      age: 18,
      email: 'fake@email.com'
    }
  },
  getters: {},
  actions: {}
})

<template>
  <div>PiniaApage</div>
  <div>姓名：{{user.name}}</div>
  <div>年龄：{{user.age}}</div>
</template>

<script>
import { useLoggedInUserStore } from '@/store/loggedInUser.js'
export default {
  name: 'PiniaDemoPage1',
  setup () {
    const user = useLoggedInUserStore()
    return {
      user
    }
  }
}
</script>

import { defineStore } from 'pinia'
export const useLoggedInUserStore = defineStore({
// id 是必填的，并且所有 Store 中唯一。因为Pinia会将它在devtools显示
  id: 'loggedInUser',
  state () {
    return {
      name: '太凉',
      age: 18,
      email: 'fake@email.com'
    }
  },
  getters: {},
  actions: {}
})

<template>
  <div>PiniaApage</div>
  <div>姓名：{{user.name}}</div>
  <div>年龄：{{user.age}}</div>
</template>

<script>
import { useLoggedInUserStore } from '@/store/loggedInUser.js'
export default {
  name: 'PiniaDemoPage1',
  setup () {
    //不用在想以前那个 user.state.name的方式获取了
    const user = useLoggedInUserStore()
    return {
      user
    }
  }
}
</script>

❌ const {name, email} = useLoggedInUserStore()

//PageComponent.vue
<template>
  <h1>你好, 我是 {{name}}，我来自地球</h1>
  <h2>联系邮箱：{{email}}</h2>
</template>
<script>
import {mapState} from 'pinia'
export default{
  computed:{
    ...mapState(useLoggedInUserStore, ['name','email'])
  }
}
</script>

//store/usePostsStore.js
import { defineStore } from 'pinia'

export const usePostsStore = defineStore({
  id: 'PostsStore',
  state: ()=>({ posts: ['post 1', 'post 2', 'post 3', 'post 4'] }),
  getters:{

    // 传统函数方式
    postsCount: function(){
      return this.posts.length
    },
    // 传统函数简写方式
    postsCount2(){
      return this.posts.length
    },
    // 箭头函数
    postsCount3:(state)=>state.posts.length,

    // ❌ 不能用箭头函数+this的方式，这种方式this指向不对
    // postsCount: ()=> this.posts.length
  }
})

<template>
  <div>Piniabpage</div>
  <div> 总数：{{postsStore.postsCount}}</div>
</template>

<script>
import { usePostsStore } from '@/store/usePostsStore.js'
export default {
  name: 'PiniaBpage',
  setup () {
    const postsStore = usePostsStore()
    return {
      postsStore
    }
  }
}
</script>

<template>
  <div> 总数：{{postsCount}}</div>
</template>

<script>
import { mapState } from 'pinia'
import { usePostsStore } from "@/store/PostsStore";

export default {
  computed:{
    ...mapState(usePostsStore, ['postsCount'])
  }
};
</script>

import { defineStore } from 'pinia'

export const usePostsStore = defineStore({
  id: 'PostsStore',
  state: () => ({
    posts: ['post 1', 'post 2', 'post 3', 'post 4'],
    user: { postsCount: 2 },
    age:18,
    errors: []
  }),
  getters: {
    postsCount: function () {
      return this.posts.length
    },
    postsCount2 () {
      return this.posts.length
    },
    // 箭头函数
    postsCount3: (state) => state.posts.length
  },
  actions: {
    insertPost () {
      //方式1：直接通过this找到对应的state修改
      this.posts.push(`post_${Date.now()}`)
      this.user.postsCount++
    },
    removePost () {
      //方式2：通过.$patch 函数方法
      this.$patch((state) => {
        state.posts.shift()
        state.user.postsCount++
      })
      
      //通过.$patch 对象方法
      this.$patch({
        age:30
      });
    }
  }
})

<template>
  <div>PiniaBpage</div>
  <div> 总数：{{postsStore.postsCount}}</div>
  <ul>
    <li
      v-for="item in postsStore.posts"
      :key="item"
    >
      {{item}}
    </li>
  </ul>
  <button @click="handleAdd">新增</button>
  <button @click="handleRemove">删除</button>
  <button @click="handleBeforeAdd">新增到前面</button>
</template>

<script>
import { usePostsStore } from '@/store/usePostsStore.js'
  
export default {
  name: 'PiniaBpage',
  setup () {
    const postsStore = usePostsStore()

    // 新增
    const handleAdd = () => {
      postsStore.insertPost()
    }

    // 删除
    const handleRemove = () => {
      postsStore.removePost()
    }
    // 新增到前面，也可以在这里通过$patch修改，同样这里也可以直接修改
   const  handleBeforeAdd=()=>{
     postsStore.$patch((state) => {
        state.posts.shift()
        state.user.postsCount++
     })
   }
    return {
      postsStore,
      handleAdd,
      handleRemove,
      handleBeforeAdd
    }
  }
}
</script>

// PostEditorComponent.vue
<template>
  <input type="text" v-model="post" />
  <button @click="insertPost(post)">保存</button>
</template>
<script>
import {mapActions} from 'pinia'
import { usePostsStore } from '@/store/PostsStore';
export default{
  data(){
    return { post: '' }
  }, 
  methods:{
    ...mapActions(usePostsStore, ['insertPost'])
  }
}
</script>

import { useAuthStore } from './auth-store'

export const useSettingsStore = defineStore('settings', {
  state: () => ({
    // ...
  }),
  actions: {
    async fetchUserPreferences(preferences) {
      const auth = useAuthStore()
      if (auth.isAuthenticated) {
        this.preferences = await fetchPreferences()
      } else {
        throw new Error('User must be authenticated')
      }
    },
  },
})