Using primary keys with Ember Data

Question

I've been struggling for the past few days with primary keys and the last version of Ember Data.

I first read how to do it on the Breaking Changes file on GitHub, but it's apparently outdated. I tried several other ways (with the help of Peter Wagenet on IRC), but none of them seem to work.

I would like to make slug my primary key on my model, and also since I'm working with MongoDB, I would like to use _id instead of id.

Has anyone figured out how to do this? My underlying problem is that model records get loaded twice when I do several App.MyModel.find() on the model.

Answer 1

As of Ember Data 1.0 beta you define primaryKey on the respective serializer.

For the entire app

App.ApplicationSerializer = DS.RESTSerializer.extend({
  primaryKey: '_id'
});

For a single type

App.FooSerializer = DS.RESTSerializer.extend({
  primaryKey: '_id'
});

You will still refer to it as id on the model, but Ember Data will serialize/deserialize it to _id during transfer.

Example: http://emberjs.jsbin.com/OxIDiVU/635/edit

Read More about it here: http://emberjs.com/api/data/classes/DS.RESTSerializer.html#property_primaryKey

Answer 2

I would like to make slug my primary key on my model, and also since I'm working with MongoDB, I would like to use _id instead of id.

Use the adapter's map API to specify the attribute that should be used as primary key:

App.Adapter.map('App.Person', {
  primaryKey: '_id'
});

See serializer.js api docs for detail. If you need to further customize how the records id is serialized, use the addId hook described here.

Since ember-data is still under active development, documentation on this feature is somewhat limited and may change before 1.0 release. In the meantime refer to the ember-data test suite to see examples of this in action. For example:

• mapped primary keys are respected when serializing a record to JSON demonstrates how an _id attribute will be included in json when a record is saved
• mapped primary keys are respected when materializing a record from JSON shows how JSON with _id attribute will be transformed into a record with the correct id

Answer 3

In case the solution suggested by Nikita doesn't work (didn't for me using revision 11 of ember-data), here is how I changed the primary key when working with the RESTAdapter:

App.Adapter = DS.RESTAdapter.extend({
    serializer: "App.MySerializer"
});

// notice we extend the RESTSerializer, not Serializer!
App.MySerializer = DS.RESTSerializer.extend({
    primaryKey: function(type) {
        return '_id'; // you get it...
    }
});

I'm aware that this probably won't help the OP anmore but I still post it as it may be helpful for some of you.