Backbonejs - filtering collections within models - backbone.js

Question

I have a collection of Vehicle Ranges. Each Range has an array of VehicleModels containing the models in that range. i.e.
Backbone Model and Collection:
App.Models.Range = Backbone.Models.extend({});
App.Collections.Ranges = Backbone.Collection.extend({
model: Range
});
JSON:
[{
"Name": "Range A",
"VehicleModels": [
{
"Name": "1.2",
"Fuel": "Petrol"
},
{
"Name": "1.3",
"Fuel": "Petrol"
},
{
"Name": "1.6",
"Fuel": "Petrol"
}
]
},
{
"Name": "Range B",
"VehicleModels": [
{
"Name": "x1",
"Fuel": "Diesel"
},
{
"Name": "x2",
"Fuel": "Diesel"
},
{
"Name": "x3",
"Fuel": "Diesel"
}
]
}]
How can a filter the collection to return ranges than have VehicleModels with attributes that match a filter condition. i.e. return all ranges that have vehicle models with the Fuel attribute equal to 'Petrol'. Easy enough to filter the collection by model attributes like:
filterByFuel: function(fuel){
return this.models.where({'Fuel': fuel});
}
or
filterByFuel: function(fuel){
return this.models.filter(function(vehicle) {
return vehicle.get('Fuel') === fuel;
});
}
But need to search the VehicleModel collection in each Range and return the Range if there is a match.
Tips greatly appreciated.
EDIT
I have the following which seems to work, but was curious if there was a better way. Underscores "contains" function seemed like the right thing, but could not get it to work:
models = models.filter(function(range) {
if (_.where(range.get('VehicleModels'), { 'Fuel': params.fuel }).length > 0)
return range;
});

Answer 1

First of all Backbone doesn't treat nested objects as separate collections. They are just arrays.
So when you do :
this.model.get("VehicleModels")
You will only get an Array type object and not a Backbone.Collection.
To filter a plain array, you should use underscore's filter method.
_.filter( this.model.get("VehicleModels"), function(mod) { /* your condition */ } );