Saving nested collections within a model using backbone.js - mongodb

Question

I am having some issues getting Backbone to save multiple layers of collections. I have the following models:
var Question = Backbone.Model.extend({
urlRoot: "/question"
});
var QuestionList = Backbone.Collection.extend({
model: Question,
url: "/question",
parse: function(response) {
return response.objects;
}
});
var QuestionBank = Backbone.Model.extend({
urlRoot: "/questionbank"
});
var QuestionBankList = Backbone.Collection.extend({
model:QuestionBank,
url: "/questionbank",
parse: function(response) {
return response.objects;
}
});
var Answer = Backbone.Model.extend({
urlRoot: "/answer"
})
var AnswerList = Backbone.Collection.extend({
model: Answer,
url: "/answer",
parse: function(response) {
return response.objects;
}
});
A questionbank has many questions, and a question has many answers.
When I save my collection the model is correct, but the JSON that is sent out does not include the second level of collection (the answers):
{"active_question_bank": true, "id":
"51a8c5d72ace7a458fd0d000", "question_bank_name": "New Q", "questions":
[{"active_question": true, "answers": [], "difficulty": null,
"id": "51a8d1be2ace7a458fd0d008", "question": "What is your favorite Color?",
"question_is_and_type": false, "question_type": 1, "resource_uri":
"/question/51a8d1be2ace7a458fd0d008", "tags": [""]}], "resource_uri":
"/questionbank/51a8c5d72ace7a458fd0d000"}
In particular it sends a blank "answers": [] every time. I'm relatively new to backbone, so perhaps this is an impossible task, but the concept seems fairly trivial.

Answer 1

Try defining the models and collections in the following pattern and then check the JSON being sent to the server.
var Answer = Backbone.Model.extend({
urlRoot: "/answer",
});
var AnswerCollection = Backbone.Collection.extend({
model: Answer,
urlRoot: "/answer",
});
// a question can contain many answers which can be accessed via AnswerList
var Question = Backbone.Model.extend({
urlRoot: "/question",
defaults: {
AnswerList: new AnswerCollection(),
},
parse: function(response) {
response.AnswerList= new AnswerCollection(response.AnswerList);
return response;
}
});
var QuestionCollection = Backbone.Collection.extend({
model: Question,
url: "/question",
});
// question-bank contains many questions which can be accessed via QuestionList
var QuestionBank = Backbone.Model.extend({
urlRoot: "/questionbank",
defaults: {
QuestionList: new QuestionCollection(),
},
parse: function(response) {
response.QuestionList = new QuestionCollection(response.QuestionList);
return response;
}
});