Question

I have some global parameters that I want to be sent in every time I call a fetch on a collection… my issue is I don’t want to declare the data: { ... } every time I fetch.

Is there a way I can provide default parameters inside the Collection itself with the possibility to add more or override some?

For example:

Instead of doing this every time:

this.articlesCollection.fetch({
    dataType: 'jsonp',
    data: {
        deviceType: GlobalVars.deviceType,
        memberId: GlobalVars.memberId,
        authToken: GlobalVars.authToken,
        targetObjectId: userId,
        limit: 50,
        excludeArticleBodies: true,
        excludeViewedItems: false
    },
    success: function() {
        _this.render();
    }
});

I’d like to just provide a one or two parameters and a success function, like this:

this.articlesCollection.fetch({
    data: {
        targetObjectId: userId
    },
    success: function() {
        _this.render();
    }
});

… and have the Collection look something like:

define([
  'underscore',
  'backbone',
  'global',
  'utilities',
  'models/article/ArticleModel'
], function(_, Backbone, GlobalVars, Utils, ArticleModel){

  var ArticlesCollection = Backbone.Collection.extend({

      model: ArticleModel,

      initialize : function(view) {
          this.view = view;
      },

      dataType: 'jsonp',
      data: {
          deviceType: GlobalVars.deviceType,
          memberId: GlobalVars.memberId,
          authToken: GlobalVars.authToken,
          limit: 50,
          excludeArticleBodies: true,
          excludeViewedItems: false
       },

      url : function() {
        return GlobalVars.baseAPIUrl + '/API/GetArticles';
      },

      parse : function(data) {  
        return data.Articles;
      }     

  });

  return ArticlesCollection;

});

Answer 1

Here’s a working jsFiddle with one approach: http://jsfiddle.net/LEuGq/1/

Basically, you configure both an object of defaultParams and params as properties of your collection, which are used to dynamically compute the correct URL when fetch() is called. This way is probably more in alignment with backbone than changing the API of fetch() to accept parameters, which it is not designed to do.

var ParamCollection = Backbone.Collection.extend({

    defaultParams: {deviceType: 'raceCar', limit: 42},
    params: {},
    url: function() {
      return "/paramcollection?" + $.param(_.defaults(this.params, this.defaultParams));
    }
});
var paramCollection = new ParamCollection();
paramCollection.params.excludeArticleBodies = true;
paramCollection.params.limit = 52;
$("#debug").append(paramCollection.url());