javascript - How do you create a custom adapter for ember.js?

Question

I'm planning on using ember.js, however my REST api doesn't exactly align with the packaged REST Adapter. I would like to "override" find and be able to put my own ajax in it. I dislike how an ember findAll retrieves all my documents with no options for pagination, so that along with other query parameters would be useful --which is why I want to write my own ajax. I've been unable to find any documentation on how I would go about doing this.

Answer 1

For Ember Data

This is up to date as of Ember Data 1.0 beta 9.

Extend one of the Ember Data Adapters. To make it site wide:

App.ApplicationAdapter = DS.RESTAdapter.extend(....

To make it model specific:

App.FooAdapter = DS.RESTAdapter.extend(...

Then you will define the implementation you'd like to override. You always have the option to call this._super and revert to the base implementation. e.g.

App.NotesAdapter = DS.RESTAdapter.extend({
  find: function(store, type, id) {
    id = "foo" + id;
    return this._super(store, type, id);
  }
});

Or you can completely override the implementation:

App.NotesAdapter = DS.RESTAdapter.extend({
  find: function(store, type, id) {
    // Do your thing here
    return this.ajax(this.buildURL(type.typeKey, id), 'GET');
  },

  findAll: function(store, type, sinceToken) {
    // Do your thing here
    var query;

    if (sinceToken) {
      query = { since: sinceToken };
    }

    return this.ajax(this.buildURL(type.typeKey), 'GET', { data: query });
  },

  findQuery: function(store, type, query) {
    // Do your thing here
    return this.ajax(this.buildURL(type.typeKey), 'GET', { data: query });
  },

  findMany: function(store, type, ids, owner) {
    return this.ajax(this.buildURL(type.typeKey), 'GET', { data: { ids: ids } });
  },
   .....
});

To see the complete api you can override see: http://emberjs.com/api/data/classes/DS.RESTAdapter.html

Serializer

Often more important will be rolling your own serializer for massaging the data to fit your rest endpoint. Here's some useful information from the transition document https://github.com/emberjs/data/blob/master/TRANSITION.md .

The short version is that once an Ajax request has completed, the resulting payload is sent through the following hooks:

1. The payload is sent to extractSingle if the original request was for a single record (like find/save) or extractArray if the original request was for an Array of records (like findAll/findQuery)
2. The default behavior of those methods is to pull apart the top-level of the payload into multiple smaller records.
3. Each of those smaller records is sent to normalize, which can do normalization a record at a time.
4. Finally, specific types of records can be specially normalized.

    App.PostSerializer = DS.RESTSerializer.extend({
      extractSingle: function(store, type, payload, id) {
        // massage
        this._super(store, type, payload, id);
      },
      extractArray: function(store, type, payload) {
        // massage
        this._super(store, type, payload);
      },
      normalize: function(type, hash, property) {
        // massage
        this._super(type, hash, property);
      }
    });

• use extractSingle and extractArray when the top-level of your payload is organized differently than Ember Data expects
• use normalize to normalize sub-hashes if all sub-hashes in the payload can be normalized in the same way.
• use normalizeHash to normalize specific sub-hashes.
• make sure to call super if you override extractSingle, extractArray or normalize so the rest of the chain will get called.

Rolling your own

App.FooAdapter = Ember.Object.extend({
  find: function(id){
    return $.getJSON('http://www.foolandia.com/foooo/' + id);
  }
});

Then from your route, or wherever

App.FooRoute = Ember.Route.extend({
  model: function(){
    var adapter = App.FooAdapter.create();
    return adapter.find(1);
  }
});

Now personally I'd inject the adapter onto the routes just to make my life easier:

App.initializer({
    name: "fooAdapter",

    initialize: function (container, application) {
        application.register("my:manager", application.FooAdapter);
        application.inject("controller", "fooAdapter", "my:manager");
        application.inject("route", "fooAdapter", "my:manager");
    }
});

Then on the route you could be lazier and do:

App.FooRoute = Ember.Route.extend({
  model: function(){
    return this.fooAdapter.find(1);
  }
});

Example: http://emberjs.jsbin.com/OxIDiVU/676/edit

You can read more about Ember without Ember Data: Ember without Ember Data