javascript - 如何监听来自vuex的compute数组的变化

Question

我有一个计算数组，它是根据商店的状态组装的:

computed: {
  ...mapGetters([
    '$tg',
  ]),
  ...mapState({
    podcastList: state => state.listening.podcastList,
  }),
  tabList: {
    get() {
      const questionTitle = this.$tg('questions');
      const list = this.podcastList.map((poadcast, index) => ({
        ...poadcast,
        title: `${questionTitle}${index + 1}`,
        answers: [...poadcast.answers],
      }));
      return list;
    },
    set(value) {
      // I want dispatch action here..
      console.log('set', value);
    },
  },
}

podcastList的构造是一个对象数组:

[ 
  { 
    id: 1,  
    answers: [ 
      { id: 1, content:'foo'}, { id: 2, content: 'bar'}
    ]
  }, //.....
]

我正在使用v-for来创建一组与答案绑定(bind)的输入。它看起来像:

<div class="columns is-vcentered" v-for="(answer, index) in tab.answers" :key="index">
 <input type="text" v-model="answer.content"/>
</div>
// tab is an element of my tabList

我的问题:如果我更改输入的值，计算的 setter 将不会被触发。我会收到消息

"Error: [vuex] do not mutate vuex store state outside mutation handlers."

我知道我不能直接修改状态，但我不知道如何调度操作，如 official website 的示例。有人可以帮忙吗？非常感谢。

Answer 1

v-model 仅在将 tabList 映射到其中时才有效(类似于组件中的 v-model="tabList")。

您必须使用 value 和 @input 而不是 v-model 直接更改每个答案:

<div class="columns is-vcentered" v-for="(answer, index) in tab.answers" :key="index">
 <input type="text" :value="answer.content"
       @input="$store.commit('updateAnswer', { podcastId: tab.id, answerId: answer.id, newContent: $event.target.value })" />
</div>
// tab is an element of my tabList

updateAnswer 突变如下:

mutations: {
  updateAnswer (state, { podcastId, answerId, newContent }) {
    state.listening.podcastList
        .find(podcast => podcast.id === podcastId)
        .map(podcast => podcast.answers)
        .find(answer => answer.id === answerId).content = newContent;
  }
}

--

您也许可以通过创建方法来减少样板:

methods: {
  updateAnswer(tab, answer, event) {
    this.$store.commit('updateAnswer', { podcastId: tab.id, answerId: answer.id, newContent: event.target.value });
  }
}

并像这样使用它:

<input type="text" :value="answer.content" @input="updateAnswer(tab, answer, $event)" />

或者通过创建一个组件(可以是功能性的):

Vue.component('answer', {
  template: `
    <input type="text" :value="answer.content"
           @input="$store.commit('updateAnswer', { podcastId: tab.id, answerId: answer.id, newContent: $event.target.value })" />
  `
  props: ['tab', 'answer']
})

并像这样使用它:

<div class="columns is-vcentered" v-for="(answer, index) in tab.answers" :key="index">
 <answer :tab="tab" :answer="answer"/>
</div>