Nested attributes don't save and fetch as expected

[toddself]

I could be doing it wrong, but I would expect the following to work:

var Backbone = require('backbone');
var assert = require('assert');

var InnerModel = Backbone.Model.extend({
   urlRoot: '/innermodel'
});
InnerModel.prototype.sync = require('backbone-orm').sync(InnerModel);

var OuterModel = Backbone.Model.extend({
    urlRoot: 'mongodb://localhost:27017/testModel',
    schema: {
        innerModel: function(){
            return ['hasOne', InnerModel, {embed: true}];
        }
    }
});
OuterModel.prototype.sync = require('backbone-mongo').sync(OuterModel);

var om = new OuterModel({foo: 'bar', innerModel: new InnerModel({bar: 'baz'})});
om.save(function(err, om){
    if(err) return err;
    var om2 = new OuterModel({id: om.id});
    om2.fetch(function(om2){
       assert.deepEqual(om2.get('innerModel').attributes, om.get('innerModel').attributes);
    });
});

Errors out with:

TypeError: Cannot call method 'get' of null
    at repl:5:23
    at /Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/utils.js:108:16
    at Object.success (/Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/utils.js:92:18)
    at /Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/extensions/model.js:407:66
    at /Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/utils.js:108:16
    at success (/Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/utils.js:92:18)
    at Object.options.success (/Users/todd/src/conde/fauxpilot/node_modules/backbone/backbone.js:433:22)
    at /Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/lib/sync.js:77:26
    at /Users/todd/src/conde/fauxpilot/node_modules/backbone-mongo/node_modules/backbone-orm/lib/cursor.js:236:22
    at QueryCache.module.exports.QueryCache.set

Because om2.get('innerModel') is null. Expected it to be the innerModel instance generated when om was generated.

It looks like since toJSON doesn't handle nested models correctly, the create method on line 63 of src/sync.coffee returns no data for the nested attribute.

[toddself]

Or is there another way this is supposed to work? Should I be providing some sort of extra template? The examples are pretty light when it comes to saving/fetching nested models.

[kmalakoff]

Hello!

I've taken a look at your code and see that there are some conventions that need to be followed (some undocumented):

1. Add callbacks are of the form "(err, result) ->" - that means "fetch(function(om2) {})" should be "fetch(function(err, om2) {})"

2. The naming convention for models are:

   a) urls are underscored, pluralized: "/innermodel" should be "/inner_models"

   b) relationships are also underscored, but either pluralized or singularized depending on the relationship plurality: "innerModel" should be "inner_model"

3. Because the embedded relationship is stored on the OuterModel, the relationship should be "belongsTo" instead of "hasOne".

Other things

1. Instead of using a url on the InnerModel, you could add a property 'model_name: "InnerModel"' to it (with CoffeeScript in Node, model_name and url are optional).

2. The function around a relationship is only necessary for breaking dependency cycles so "innerModel: function(){return [...]}" could be simplified to "inner_model: [...]"

3. We typically don't use the fetch mechanic, but findOne:

  OuterModel.findOne om.id, (err, om3) ->
    assert.deepEqual(om3.get('inner_model').attributes, om.get('inner_model').attributes)

You can find a working version of your code here. Also, I will update the documentation to make the conventions more clear.

Just let me know if you have any more problems.

[toddself]

@kmalakoff omg thank you so much for going through this! I'm going to go over it and implement the changes :)

Hope you had an excellent holiday!