Question

Have an array of id’s

['tom','tim','joe','matt','scott']

Each model has an attribute that has an id.

How can I grab all 5 of the models and put in a new collection?

Answer 1

How about using the underscore filter method on the corresponding collection?

var ids = ['tom','tim','joe','matt','scott'];

var matches = collection.filter(function (model) { 
   return ids.indexOf(model.id) > -1; 
});

If you need to fetch the models from your persistence layer, you might consider generating a collection of models with the id attribute set and providing an appropriate endpoint to populate the other attributes:

var MyCollection = Backbone.Collection.extend({
  model: MyModel, // whatever your model is
  url: '/byname'  // whatever the endpoint is
});

var models = [];

_.each(ids, function (id) {
  models.push({ id: id });
});

var collection = new MyCollection;
collection.fetch({ models: models }); // fetch the associated models

Whatever endpoint you provide (/byname in the example above) should be prepared to generate a collection containing each model whose id was specified in the models parameter.