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>

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。

你也可以使用debouncedWatch (vue使用函数)安全地观看它

  debouncedWatch(
    lines,
    () => {
      console.log('changed');
    },
    500,
  );

当你想要在状态级别上观看时，可以这样做:

let App = new Vue({
    //...
    store,
    watch: {
        '$store.state.myState': function (newVal) {
            console.log(newVal);
            store.dispatch('handleMyStateChange');
        }
    },
    //...
});

如果你使用typescript，那么你可以:

import {Watch} from "vue-property-decorator"; ．． @Watch (" $ store.state.something”) private watchSomething() { //使用这个。$store.state。可以访问的东西 .．. ｝

在组件内部，创建一个计算函数

computed:{
  myState:function(){
    return this.$store.state.my_state; // return the state value in `my_state`
  }
}

现在可以观察计算出的函数名，比如

watch:{
  myState:function(newVal,oldVal){
    // this function will trigger when ever the value of `my_state` changes
  }
}

在vuex状态my_state中所做的更改将反映在计算函数myState中，并触发手表函数。

如果状态my_state包含嵌套数据，则处理程序选项将提供更多帮助

watch:{
  myState:{
    handler:function(newVal,oldVal){
      // this function will trigger when ever the value of `my_state` changes
    },
    deep:true
  }
}

这将监视my_state存储中的所有嵌套值。