How to deal with many2many objects in EmberJS client?

Question

I have a data model that has a many to many relship. Let's say that I have a Producer model, and a Customer module. A customer can buy from any number of producers, and a produces can serve any number of customers.

In the backend, I have the standard relational configuration for this with three tables:

• customer
• producer
• customer2producer

My Ember models currently look like this:

// models/producer.js
import DS from 'ember-data';

export default DS.Model.extend({
  customers: DS.hasMany('module'),
});

// models/customer.js
import DS from 'ember-data';

export default DS.Model.extend({
  producers: DS.hasMany('module'),
});

Right now I am working with fixtures, and what I do is just define the customers and producers arrays with the ids of the "targets". The question is, that sooner or later I will switch to a real REST backend, and that means I have to deal with the model mismatch. I think I have to options:

• Define a Ember model customer2producer. This will probably work, but I guess I will have to write a lot of boilerplate, and most probably the relationships will not be accessible from the model (customer.get('producers') won't work directly, I would probably have to play with and do something like in this question:

  Many to Many Relationships with Ember, ember-data and Rails

• Hook into the serializer/deserializer system and translate the backend customer2producer objects into Ember model references. I am not completely sure this is possible, but I would say it is from reading quickly these SO questions:

  How to save models with many-to-many relationship in Ember.js?

  Saving nested models

I guess this is a very common scenario, and I would like to know what is the cleanest way to approach the problem. Thanks in advance.

Answer 1

Your database doesn't need to map onto your REST API. Particularly you don't have the limitation of flat data (nor do you in some databases these days).

If you're in control of your backend API, I would just return responses like:

GET /customers

{
  customers: [
    {id: 1, producers: [1, 2]},
    {id: 2, producers: []},
  ]
}

GET /producers

{
  producers: [
    {id: 1, customers: [1]},
    {id: 2, customers: [1]}
  ]
}

Your REST backend should be the one concerned about serializing and deserializing to the database models, not your frontend app.

If you ever have something consuming the API that you can't instantly modify (mobile app, third-parties etc.) your REST API will naturally grow disjoint from your backend models over time anyways, giving you data transformation work. So I really want to compel you to just do what makes sense for REST.