如何从vuex观看存储值?

正如Gabriel所说，观察商店变化的最佳方法是使用mapGetters。但在某些情况下，你不能通过mapGetters来实现，例如，你想从store中获取一些东西，使用parameter:

getters: {
  getTodoById: (state, getters) => (id) => {
    return state.todos.find(todo => todo.id === id)
  }
}

在这种情况下，你不能使用mapGetters。你可以试着这样做:

computed: {
    todoById() {
        return this.$store.getters.getTodoById(this.id)
    }
}

但不幸的是，todoById仅在以下情况下才会更新。Id改变了

如果你想更新你的组件在这种情况下使用。$store。腕表解决方案由龚提供。或者有意识地处理组件并更新它。当需要更新todoById时，使用todoById。

2017-09-11 01:37:20

如果您只是想监视一个状态属性，然后根据该属性的变化在组件中进行相应的操作，请参阅下面的示例。

在store.js:

export const state = () => ({
 isClosed: false
})
export const mutations = {
 closeWindow(state, payload) {
  state.isClosed = payload
 }
}

在这个场景中，我创建了一个布尔状态属性，我将在应用程序的不同地方更改，如下所示:

this.$store.commit('closeWindow', true)

现在，如果我需要在其他组件中监视状态属性，然后更改本地属性，我会在挂载的钩子中写入以下内容:

mounted() {
 this.$store.watch(
  state => state.isClosed,
  (value) => {
   if (value) { this.localProperty = 'edit' }
  }
 )
}

首先，我在状态属性上设置了一个监视器，然后在回调函数中，我使用该属性的值来更改localProperty。

我希望这能有所帮助!

2019-11-27 00:18:59

您可以使用Vuex操作、getter、计算属性和监视器的组合来侦听Vuex状态值的变化。

HTML代码:

<div id="app" :style='style'>
  <input v-model='computedColor' type="text" placeholder='Background Color'>
</div>

JavaScript代码:

'use strict'

Vue.use(Vuex)

const { mapGetters, mapActions, Store } = Vuex

new Vue({
    el: '#app',
  store: new Store({
    state: {
      color: 'red'
    },
    getters: {
      color({color}) {
        return color
      }
    },
    mutations: {
      setColor(state, payload) {
        state.color = payload
      }
    },
    actions: {
      setColor({commit}, payload) {
        commit('setColor', payload)
      }
    }
  }),
  methods: {
    ...mapGetters([
        'color'
    ]),
    ...mapActions([
        'setColor'
    ])
  },
  computed: {
    computedColor: {
        set(value) {
        this.setColor(value)
      },
      get() {
        return this.color()
      }
    },
    style() {
        return `background-color: ${this.computedColor};`
    }
  },
  watch: {
    computedColor() {
        console.log(`Watcher in use @${new Date().getTime()}`)
    }
  }
})

参见JSFiddle演示。

2018-03-26 13:58:14

====== store ===== import Vue from 'vue' import Vuex from 'vuex' import axios from 'axios' Vue.use(Vuex) export default new Vuex.Store({ state: { showRegisterLoginPage: true, user: null, allitem: null, productShow: null, userCart: null }, mutations: { SET_USERS(state, payload) { state.user = payload }, HIDE_LOGIN(state) { state.showRegisterLoginPage = false }, SHOW_LOGIN(state) { state.showRegisterLoginPage = true }, SET_ALLITEM(state, payload) { state.allitem = payload }, SET_PRODUCTSHOW(state, payload) { state.productShow = payload }, SET_USERCART(state, payload) { state.userCart = payload } }, actions: { getUserLogin({ commit }) { axios({ method: 'get', url: 'http://localhost:3000/users', headers: { token: localStorage.getItem('token') } }) .then(({ data }) => { // console.log(data) commit('SET_USERS', data) }) .catch(err => { console.log(err) }) }, addItem({ dispatch }, payload) { let formData = new FormData() formData.append('name', payload.name) formData.append('file', payload.file) formData.append('category', payload.category) formData.append('price', payload.price) formData.append('stock', payload.stock) formData.append('description', payload.description) axios({ method: 'post', url: 'http://localhost:3000/products', data: formData, headers: { token: localStorage.getItem('token') } }) .then(({ data }) => { // console.log('data hasbeen created ', data) dispatch('getAllItem') }) .catch(err => { console.log(err) }) }, getAllItem({ commit }) { axios({ method: 'get', url: 'http://localhost:3000/products' }) .then(({ data }) => { // console.log(data) commit('SET_ALLITEM', data) }) .catch(err => { console.log(err) }) }, addUserCart({ dispatch }, { payload, productId }) { let newCart = { count: payload } // console.log('ini dari store nya', productId) axios({ method: 'post', url: `http://localhost:3000/transactions/${productId}`, data: newCart, headers: { token: localStorage.getItem('token') } }) .then(({ data }) => { dispatch('getUserCart') // console.log('cart hasbeen added ', data) }) .catch(err => { console.log(err) }) }, getUserCart({ commit }) { axios({ method: 'get', url: 'http://localhost:3000/transactions/user', headers: { token: localStorage.getItem('token') } }) .then(({ data }) => { // console.log(data) commit('SET_USERCART', data) }) .catch(err => { console.log(err) }) }, cartCheckout({ commit, dispatch }, transactionId) { let count = null axios({ method: 'post', url: `http://localhost:3000/transactions/checkout/${transactionId}`, headers: { token: localStorage.getItem('token') }, data: { sesuatu: 'sesuatu' } }) .then(({ data }) => { count = data.count console.log(count, data) dispatch('getUserCart') }) .catch(err => { console.log(err) }) }, deleteTransactions({ dispatch }, transactionId) { axios({ method: 'delete', url: `http://localhost:3000/transactions/${transactionId}`, headers: { token: localStorage.getItem('token') } }) .then(({ data }) => { console.log('success delete') dispatch('getUserCart') }) .catch(err => { console.log(err) }) } }, modules: {} })

2020-01-27 11:00:04

比如说，你有一篮水果，每次你从篮子里添加或取出一个水果，你想要(1)显示有关水果数量的信息，但你也(2)想要以某种奇特的方式通知水果的数量…

fruit-count-component.vue

<template>
  <!-- We meet our first objective (1) by simply -->
  <!-- binding to the count property. -->
  <p>Fruits: {{ count }}</p>
</template>

<script>
import basket from '../resources/fruit-basket'

export default () {
  computed: {
    count () {
      return basket.state.fruits.length
      // Or return basket.getters.fruitsCount
      // (depends on your design decisions).
    }
  },
  watch: {
    count (newCount, oldCount) {
      // Our fancy notification (2).
      console.log(`We have ${newCount} fruits now, yay!`)
    }
  }
}
</script>

请注意，监视对象中的函数名必须与计算对象中的函数名匹配。在上面的例子中，名字是count。

被监视属性的新值和旧值将作为参数传递到监视回调(count函数)。

篮子商店可以是这样的:

fruit-basket.js

import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

const basket = new Vuex.Store({
  state: {
    fruits: []
  },
  getters: {
    fruitsCount (state) {
      return state.fruits.length
    }
  }
  // Obviously you would need some mutations and actions,
  // but to make example cleaner I'll skip this part.
})

export default basket

你可以在以下资源中阅读更多:

计算属性和监视器 API文档:计算 API文档:观察

2017-06-03 18:21:20