vuejs rendering async function in template displays promise instead of returned data

Question

I am calling an async function which loads the profile pic, the await call returns the value to the variable 'pf' as expected, but I couldn't return that from loadProfilePic. At least for the start I tried to return a static string to be displayed as [object Promise] in vue template.

But when I remove await/asnyc it returns the string though.

<div  v-for="i in obj">
              {{ loadProfilePic(i.id) }}
</div>

   loadProfilePic: async function(id) {
           var pf = await this.blockstack.lookupProfile(id)
           return 'test data';
           //return pf.image[0]['contentUrl']

    },

Answer 1

That is because async function returns a native promise, so the loadProfilePic method actually returns a promise instead of a value. What you can do instead, is actually set an empty profile pic in obj, and then populate it in your loadProfilePic method. VueJS will automatically re-render when the obj.profilePic is updated.

<div  v-for="i in obj">
    {{ i.profilePic }}
</div>

loadProfilePic: async function(id) {
   var pf = await this.blockstack.lookupProfile(id);

   this.obj.filter(o => o.id).forEach(o => o.profilePic = pf);
}

See proof-of-concept below:

new Vue({
  el: '#app',
  data: {
    obj: [{
      id: 1,
      profilePic: null
    },
    {
      id: 2,
      profilePic: null
    },
    {
      id: 3,
      profilePic: null
    }]
  },
  methods: {
    loadProfilePic: async function(id) {
      var pf = await this.dummyFetch(id);
      this.obj.filter(o => o.id === id).forEach(o => o.profilePic = pf.name);
    },
    dummyFetch: async function(id) {
      return await fetch(`https://jsonplaceholder.typicode.com/users/${id}`).then(r => r.json());
    }
  },
  mounted: function() {
    this.obj.forEach(o => this.loadProfilePic(o.id));
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
  <div v-for="i in obj">
    {{ i.profilePic }}
  </div>
</div>