Multiple Baseline Sampling

Question

Is there a sexier way to do the following:

scheduleSubjects.fetch({ success: function(){ subjectList.fetch({ success: function(){ assignments.fetch({ success: function(){ _this.render(); } }); } }); } }); 

I want all the data to be extracted before I start manipulating it.

Thanks.

Answer 1

Using jQuery pending objects , you can use $.when to call a callback when several asynchronous calls are completed:

 $.when(scheduleSubjects.fetch(), subjectList.fetch(), assignments.fetch()).then(_this.render); 

Note that this works because JQuery.ajax , and therefore Backbone.fetch , returns a pending object.

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An alternative to .then is .done , which passes you the parameters of the original callbacks (which you don't need in the OP, but you can in some cases):

 $.when(scheduleSubjects.fetch(), subjectList.fetch(), assignments.fetch()) .done(function(scheduleSubjects, subjectList, assignments) { _this.render(); }) ); 

Answer 2

 var collections = [scheduleSubjects, subjectList, assignments]; var complete = _.invoke(collections, 'fetch'); $.when(null, complete).then(function(){ _this.render(); }); 

use Promises and Underscore _.invoke() !

Answer 3

You can use promises:

 scheduleSubjects.done(function () { subjectList.fetch(); }); subjectList.done(function () { assignments.fetch(); }); assignments.done(function () { _this.render(); }); scheduleSubjects.fetch(); 

or event listeners:

 subjectList.listenToOnce(scheduleSubjects, 'sync', subjectList.fetch); assignments.listenToOnce(subjectList, 'sync', assignments.fetch); this.listenToOnce(assignments, 'sync', this.render); scheduleSubjects.fetch(); 

You do not need to define these listeners within the view. they can live at the application level. The only thing that draws attention is the visualization when assignments retrieved

Answer 4

The only way I can do this is with the bind() and trigger() baseline.

With events, you can achieve this functionality. Not sure if there is a better way. Once you have downloaded your first collection, you can start downloading the second. Theoretically, the two collections should not be combined in your example. The event-based load will be separated by subjectList and scheduleSubjects .