[example request] Basic usage with `ember-ajax`

There are example that uses low-level xhr, but the most common use case (apart from Ember Data) is ember-ajax.

What is the most efficient and compact way of using ember-concurrency with ember-ajax? Is it possible to cancel ember-ajax requests?

[robclancy]

ember-ajax now supports this on master. Not sure if there are plans for ember-concurrency to cancel the requests itself when things like a component gets destroyed.

Here is an example of what I am doing (changed code from what I actually used so could be mistakes)

    let promise;
    try {
      promise = yield this.requestSomethingWithEmberAjax();
    } finally {
      promise.xhr.abort();
    }

[machty]

@robclancy that looks good to me; do you even need to check ready state? In my experience abort()ing a complete XHR just no-ops.

In an upcoming version of EC it’ll be possible to import a symbol from EC and use it to implement a method on objects or their prototypes so that when they’re yielded in an EC task, it’ll provide EC with extra information as to how to cancel them.

The goal is that you’d be able to implement this fn on ember-ajax’s promise, something like

https://github.com/ember-cli/ember-ajax/blob/master/addon/-private/promise.js

import AJAXPromise from 'ember-ajax/-private/promise';
import { YIELDABLE } from 'ember-concurrency'; // this API not on master yet

AJAXPromise.protoype[YIELDABLE] = function * (promise, taskInstance) {
    try {
      return yield this.requestSomethingWithEmberAjax();
    } finally {
      promise.xhr.abort();
    }
}

This would make it so that anywhere else in your code you could just write

  ajax: Ember.inject.service(),
  myTask: task(function * () {
    let a = yield this.get('ajax').request('/posts');
    let b = yield this.get('ajax').request('/posts');
    let c = yield this.get('ajax').request('/posts');
  })

I’m not 100% I’ll be exposing this since it’s kind of changes behavior everywhere and might “over-cancel” in some cases but I’m leaning towards adding it.