CODEWITHSUNDEEP
vue.jsvuejs2vuex
Jujubes
Jujubes

Reputation: 434

Vue computed property not responding to state change

I cannot figure out why the details computed property in the following component is not updating when the fetch() method is called:

<template>
  <div>
  {{ haveData }} //remains undefined
  </div>
</template>

<script>
export default {
  props: {
    group: {
      type: Object,
      required: true
    },
  },
  computed: {
    currentGroup() {
      return this.$store.getters['user/navbar_menu_app_current_group'](
        this.group.id
      )

      /*-- which is the following function 
        navbar_menu_app_current_group: state => item => {
        return state.menu.find(m => {
          return m.id == item
        })
        }
      */

      /*-- this function returns an object like so 
        {
          id: 1,
          label: 'kity cats',
        }
        ***details --> IS NOT DEFINED. If I add it to the current group as null, my problem goes away. However, this is a previous API call that does not set the `details` parameter.
      */
    },
    details() {
      let c = this.currentGroup.details
      console.log(c) // returns undefined, which makes sense, but it should be updated after this.fetch() is called
      return c
    },
    haveData() {
      return this.details != null
    }
  },
  methods: {
    async fetch() {
      await this.$store.dispatch(
        'user/navbar_menu_app_details_get',
        this.group.id
      )
      //This is setting the "details" part of the state on menu which is referred to in the computed properties above
      //Previous to this there is no state "this.group.details"
      //If I add a console log to the mutation the action calls, I get what is expected.
    }
  },
  created() {
    if (!this.haveData) {
      this.fetch()
    }
  }
}
</script>

If I change the array items to include details, it works:

{
  id: 1,
  label: 'kity cats',
  details: null  // <-- added
}

The unfortunate part is that the array is created from a large API call, and adding the details seems unnecessary, as it may never be needed.

How can I get the computed properties to work without adding the details:null to the default state?

Attempt 1:

// Vuex mutation
navbar_menu_app_details_set(state, vals) {
  let app = state.menu.find(item => {
    return item.id == vals[0] //-> The group id passing in the dispatch function 
  })

  //option 1 = doesn't work
  app = { app, details: vals[1] } //-> vals[1] = the details fetched from the action (dispatch)

  //option 2 = doesnt work
  app.details = vals[1]

  //option 3 = working but want to avoid using Vue.set()
  import Vue from 'vue' //Done outside the actual function
  Vue.set( app, 'details', vals[1])
},

Attempt 2:

// Vuex action
navbar_menu_app_details_get(context, id) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      context.commit('navbar_menu_app_details_set', [
        context.getters.navbar_menu_app_current(id), //-> the same as find function in the mutation above
        apps[id]
      ])
      resolve()
    }, 1000)
  })
}

// --> mutation doesn't work
navbar_menu_app_details_set(state, vals) {
  vals[0].details = vals[1]
},

Upvotes: 2

Views: 2949

Answers (2)

tony19
tony19

Reputation: 138276

The Vue instance is available from a Vuex mutation via this._vm, and you could use vm.$set() (equivalent to Vue.set()) to add details to the menu item:

navbar_menu_app_details_set(state, vals) {
  let app = state.menu.find(item => {
    return item.id == vals[0]
  })

  this._vm.$set(app, 'details', vals[1])
},

Upvotes: 1

Mukundhan
Mukundhan

Reputation: 3457

All Objects in Vue are reactive and are designed in a way such that only when the object is re-assigned, the change will be captured and change detection will happen.

Such that, in your case, following should do fine.

app = { ...app, details: vals[1] }

Upvotes: 1

Related Questions