我同时使用vuex和vuejs 2。

我是vuex的新手,我想看一个商店变量的变化。

我想在我的vue组件中添加手表功能

这是我目前所拥有的:

import Vue from 'vue';
import {
  MY_STATE,
} from './../../mutation-types';

export default {
  [MY_STATE](state, token) {
    state.my_state = token;
  },
};

我想知道my_state是否有任何变化

我怎么看店。My_state在我的vuejs组件?


当前回答

你不应该使用组件的监视器来监听状态的变化。我建议您使用getter函数,然后在组件中映射它们。

import { mapGetters } from 'vuex'

export default {
  computed: {
    ...mapGetters({
      myState: 'getMyState'
    })
  }
}

在你的店里:

const getters = {
  getMyState: state => state.my_state
}

您应该能够通过使用此功能侦听对您的商店所做的任何更改。myState在你的组件。

https://vuex.vuejs.org/en/getters.html#the-mapgetters-helper

其他回答

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。

这是为所有的人,不能解决他们的问题与getter,实际上真的需要一个监视器,例如,与非Vue第三方的东西(见Vue监视器何时使用监视器)。

Vue组件的监视器和计算值也都适用于计算值。所以vuex也没有什么不同:

import { mapState } from 'vuex';

export default {
    computed: {
        ...mapState(['somestate']),
        someComputedLocalState() {
            // is triggered whenever the store state changes
            return this.somestate + ' works too';
        }
    },
    watch: {
        somestate(val, oldVal) {
            // is triggered whenever the store state changes
            console.log('do stuff', val, oldVal);
        }
    }
}

如果只是结合本地和全局状态,mapState的文档也提供了一个例子:

computed: {
    ...mapState({
        // to access local state with `this`, a normal function must be used
        countPlusLocalState (state) {
          return state.count + this.localCount
        }
    }
})

你也可以订阅商店突变:

store.subscribe((mutation, state) => {
  console.log(mutation.type)
  console.log(mutation.payload)
})

https://vuex.vuejs.org/api/#subscribe

Vue手表处于字符串状态

状态:

$store.state.local_store.list_of_data

内部组件

  watch: {
       
       '$store.state.local_store.list_of_data':{//<----------your state call in string
        handler(){
            console.log("value changeing in party sales entry"); //<---do your stuff here
        },
        deep:true
       }

    },

我想尽了一切办法让它运转起来。

理论

我发现,出于某种原因,对$store对象的更改不一定会触发.watch方法。我的解决办法是

Store Create a complex data set which should but doesn't propagate changes to a Component Create an incrementing counter in the state to act as a flag, which does propagate changes to a Component when watched Create a method in $store.mutators to alter the complex dataset and increment the counter flag Component Watch for changes in the $store.state flag. When change is detected, update locally relevant reactive changes from the $store.state complex data set Make changes to the $store.state's dataset using our $store.mutators method

实现

它的实现是这样的:

商店

let store = Vuex.Store({
  state: {
    counter: 0,
    data: { someKey: 0 }
  },
  mutations: {
    updateSomeKey(state, value) {
      update the state.data.someKey = value;
      state.counter++;
    }
  }
});

组件

  data: {
    dataFromStoreDataSomeKey: null,
    someLocalValue: 1
  },
  watch: {
    '$store.state.counter': {
        immediate: true,
        handler() {
           // update locally relevant data
           this.someLocalValue = this.$store.state.data.someKey;
        }
     }
  },
  methods: {
    updateSomeKeyInStore() { 
       this.$store.commit('updateSomeKey', someLocalValue);
  }

可运行演示

这很复杂,但基本上我们在这里观察一个要更改的标志,然后更新本地数据以反映存储在$状态中的对象的重要更改

Vue.config.devtools = false const store = new Vuex.Store({ state: { voteCounter: 0, // changes to objectData trigger a watch when keys are added, // but not when values are modified? votes: { 'people': 0, 'companies': 0, 'total': 0, }, }, mutations: { vote(state, position) { state.votes[position]++; state.voteCounter++; } }, }); app = new Vue({ el: '#app', store: store, data: { votesForPeople: null, votesForCompanies: null, pendingVote: null, }, computed: { totalVotes() { return this.votesForPeople + this.votesForCompanies }, peoplePercent() { if (this.totalVotes > 0) { return 100 * this.votesForPeople / this.totalVotes } else { return 0 } }, companiesPercent() { if (this.totalVotes > 0) { return 100 * this.votesForCompanies / this.totalVotes } else { return 0 } }, }, watch: { '$store.state.voteCounter': { immediate: true, handler() { // clone relevant data locally this.votesForPeople = this.$store.state.votes.people this.votesForCompanies = this.$store.state.votes.companies } } }, methods: { vote(event) { if (this.pendingVote) { this.$store.commit('vote', this.pendingVote) } } } }) <script src="https://cdn.jsdelivr.net/npm/vue@2.6.12"></script> <script src="https://unpkg.com/vuex@3.5.1/dist/vuex.js"></script> <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css"> <div id="app"> <form @submit.prevent="vote($event)"> <div class="form-check"> <input class="form-check-input" type="radio" name="vote" id="voteCorps" value="companies" v-model="pendingVote" > <label class="form-check-label" for="voteCorps"> Equal rights for companies </label> </div> <div class="form-check"> <input class="form-check-input" type="radio" name="vote" id="votePeople" value="people" v-model="pendingVote" > <label class="form-check-label" for="votePeople"> Equal rights for people </label> </div> <button class="btn btn-primary" :disabled="pendingVote==null" >Vote</button> </form> <div class="progress mt-2" v-if="totalVotes > 0" > <div class="progress-bar" role="progressbar" aria-valuemin="0" :style="'width: ' + peoplePercent + '%'" :aria-aluenow="votesForPeople" :aria-valuemax="totalVotes" >People</div> <div class="progress-bar bg-success" role="progressbar" aria-valuemin="0" :style="'width: ' + companiesPercent + '%'" :aria-valuenow="votesForCompanies" :aria-valuemax="totalVotes" >Companies</div> </div> </div>