post.js

import Ember from "ember";
import DS from "ember-data";

export default DS.Model.extend({
  // Your ED relationships and properties here...
  // ...

  // Custom API
  upvote() {
    this.set('_updateEndpoint', 'upvote');

    let promise = this.save();
    promise.finally(() => this.set('_updateEndpoint', null));

    return promise;
  },
  
  downvote() {
    this.set('_updateEndpoint', 'downvote');

    let promise = this.save();
    promise.finally(() => this.set('_updateEndpoint', null));

    return promise;
  },
});