Ember-data and MongoDB, how to handle _id

Question

I\'m using ember-data with rails and MongoDB and am having problem with the way IDs are stored in MongoDB - in a _id field.

Ember-data will use id as the default field f

Answer 1

The second part of joscas's answer fixed the id issue for me with Rails4/Ruby2 except I had to .to_s the _id.

class UserSerializer < ActiveModel::Serializer
  attributes :id, :name, :email
  def id
    object._id.to_s
  end
end

Answer 2

I don't know exactly when this was added, but you can just tell Ember-Data that the primaryKey is _id:

DS.RESTAdapter.extend({
  serializer: DS.RESTSerializer.extend({
    primaryKey: '_id'
  })
});

Answer 3

Ahh, instead of including _id in your JSON, you could craft the JSON to instead use the id method rather than the _id attribute. Ways:

You could use rabl, and the JSON could be like:

object @user 
attributes :id, :email
node(:full_name) {|user| "#{user.first_name} #{user.last_name}"}

You could also craft the as_json method

class User
  def as_json(args={})
    super args.merge(:only => [:email], :methods => [:id, :full_name])
  end
end

Answer 4

I had a similar problem using ember.js with ember-resource and couchdb, which also stores it's IDs as _id.

As solution to this problem I defined a superclass for all my model classes containing a computed property to duplicate _id into id like this:

// get over the fact that couchdb uses _id, ember-resource uses id
id: function(key, value) {
    // map _id (couchdb) to id (ember)
    if (arguments.length === 1) {
        return this.get('_id');
    }
    else {
        this.set('_id', value);
        return value;
    }
}.property('_id').cacheable()

Maybe this could solve your problem too?

Answer 5

The best way is to use ActiveModel::Serializers. Since we are using Mongoid, you will need to add an include statement like that (see this gist from benedikt):

# config/initializers/active_model_serializers.rb
Mongoid::Document.send(:include, ActiveModel::SerializerSupport)
Mongoid::Criteria.delegate(:active_model_serializer, :to => :to_a)

And then include your serializer. Something like that:

# app/serializers/user_serializer.rb
class UserSerializer < ActiveModel::Serializer
  attributes :id, :name, :email
  def id
    object._id
  end 
end

This fixes the _id problem

Answer 6

If you use Mongoid3, here is the monkey patch may work for you.

https://gist.github.com/4700909