CODEWITHSUNDEEP
ember.jsember-data
Josh Padnick
Josh Padnick

Reputation: 3268

Returning a Promise from a Computed Property

I realize there have been several questions similar to this, but none of those answers seems to be resolving my issue. My objective is to take a list of language's, and filter them so that my template can display a subset of the full list.

I started off by verifying that my computed property is working:

MyController.js

// Works as expected
languagesFiltered: function() {
   return this.get('languages');
}.property('languages')

Then I added in a filter function, but here's where I ran into trouble:

MyController.js

languagesFiltered: function() {
   // console.log shows that languages is actually a promise
   var languages = this.get('languages');

   // all of this returns a promise, but Handlebars can't handle the promise
   return languages.then( function( languagesArray ) {
      return languagesArray.filter( function( item, index, enumerable) { 
         return item.get('name') !== 'English';
      });
   })
}.property('languages')

I'm attempting to use the Ember.Array.filter method (http://emberjs.com/api/classes/Ember.ArrayProxy.html#method_filter). The filter seems to be working correctly, but now languagesFiltered returns a promise, and Handlebars can't handle that.

I tried one last alternative:

MyController.js

languagesFiltered: function() {
     var languages = this.get('languages');

     // "return languages;" works
     // But "return languages.filter" returns an empty array
     return languages.filter( function( item, index, enumerable ) {
         console.log(item);
         return true;
   });
}.property('languages')

And console.log(item) never gets called. So my questions are:

I'm using Ember 1.7.0-beta4, Ember Data 1.0.0-beta10, and ember-cli 0.44. I'd upgrade to Ember 1.7.0, but there's a small bug that affects another part of our app, so we're waiting until 1.7.1. Thanks for your input!

Upvotes: 4

Views: 3004

Answers (2)

H1D
H1D

Reputation: 758

Now there are few better solutions. I use ember-promise-helpers.

So can keep your languagesFiltered code intact and do the following inside your hbs:

{{#each (await languagesFiltered) as|lang|}}
 ...
 ...

More – https://emberigniter.com/guide-promises-computed-properties/

Upvotes: 3

tikotzky
tikotzky

Reputation: 2592

You can try returning a PromiseArray instead of just the promise.

You should be able to do something like..

languagesFiltered: function() {
   // all of this returns a promise, but Handlebars can't handle the promise
   var promise = this.get('languages').then( function( languagesArray ) {
      return languagesArray.filter( function( item, index, enumerable) { 
         return item.get('name') !== 'English';
      });
   })

   return DS.PromiseArray.create({
      promise: promise
   });

}.property('languages')

Upvotes: 17

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