Question

Using the Backbone.Rpc plugin [ https://github.com/asciidisco/Backbone.rpc ] I am attempting to send parameters on the read method when fetching a collection. When working with a single model instance you can add parameters to a method call by setting the value of a model attribute.

var deviceModel = Backbone.model.extend({
  url: 'path/to/rpc/handler',
  rpc: new Backbone.Rpc(),
  methods: {
    read: ['getModelData', 'id']
  }
});
deviceModel.set({id: 14});
deviceModel.fetch(); // Calls 'read'

// Request created by the 'read' call
{"jsonrpc":"2.0","method":"getModelData","id":"1331724849298","params":["14"]};

There is no corresponding way that I am aware of, to do a similar thing prior to fetching a collection as there is no ‘set’ method available to backbone collections.

var deviceCollection = Backbone.collection.extend({
  model: deviceModel,
  url: 'path/to/rpc/handler',
  rpc: new Backbone.Rpc(),
  methods: {
    read: ['getDevices', 'deviceTypeId']
  }
});
// This is not allowed, possible work arounds?
deviceCollection.set('deviceTypeId', 2);
deviceCollection.fetch();
// Request created by the 'read' call
{"jsonrpc":"2.0","method":"getDevices","id":"1331724849298","params":["2"]};

Is it possible to pass parameters to collection methods using Backbone.Rpc? Or do I need to pass collection filters in the data object of the fetch method?

Answer 1

I updated Backbone.Rpc (v 0.1.2) & now you can use the following syntax to add “dynamic”
arguments to your calls.

var Devices = Backbone.Collection.extend({
    url: 'path/to/my/rpc/handler',
    namespace: 'MeNotJava',
    rpc: new Backbone.Rpc(),
    model: Device,
    arg1: 'hello',
    arg2: function () { return 'world' },
    methods: {
        read : ['getDevices', 'arg1', 'arg2', 'arg3']
    }
});

var devices = new Devices();
devices.fetch();

This call results in the following RPC request:

{"jsonrpc":"2.0","method":"MeNotJava/getDevices","id":"1331724850010","params":["hello", "world", "arg3"]}