How to prevent Backbone.Marionette from rendering a view if it's model hasn't been fetched?

Question

In my backbone.Marionette application I have a Model that requires an Id attribute to construct it\'s url. I therefore create the model by passing it an Id, add it to a view

Answer 1

If you truly want to prevent rendering until the model has been fetched you should reorder your calls like this:

model = new Model({_id:id});
view = new View({model:model});
model.fetch({success: function () {
  app.content.show(view);
});

Alternatively, you should think about rendering immediately and taking advantage of Marionette's blank state support.

Answer 2

I've recenlty run into the same issue and settled on a pattern of using Marionette's event system to let the views communicate their status before firing show(). I'm also using requireJS which adds some additional complexity - but this pattern helps!

I'll have one view with a UI element that when clicked, fires an event to load a new view. This could be a subview or a navview - doesn't matter.

App.execute('loadmodule:start', { module: 'home', transition: 'left', someOption: 'foo' });

That event is caught by the Wreqr 'setHandlers' and triggers a view loading sequence (in my case I'm doing a bunch of logic to handle state transitions). The 'start' sequence inits the new view and passes in necessary options.

var self = this;
App.commands.setHandlers({'loadmodule:start': function( options ) { self.start( options );

Then the view getting loading handles the collections / models and fetching on initalize. The view listens for model / collection changes and then fires a new "ready" event using wreqr's executre command.

this.listenTo( this.model, 'change', function(){
    App.execute('loadmodule:ready', { view: this, options: this.options });
}); 

I have a different handler that catches that ready event (and options, including the view opject reference) and triggers the show().

ready: function( options ) {

// catch a 'loadmodule:ready' event before proceeding with the render / transition - add loader here as well

var self = this;
var module = options.options.module;
var view = options.view;
var transition = options.options.transition;
var type = options.options.type;

if (type === 'replace') {
    self.pushView(view, module, transition, true);
} else if (type === 'add') {
    self.pushView(view, module, transition);
} else if (type === 'reveal') {
    self.pushView(view, module, transition, true);
}   

},


pushView: function(view, module, transition, clearStack) {

var currentView = _.last(this.subViews);
var nextView = App.main.currentView[module];
var self = this;

var windowheight = $(window).height()+'px';
var windowwidth = $(window).width()+'px';
var speed = 400;

switch(transition) {
case 'left':

    nextView.show( view );

    nextView.$el.css({width:windowwidth,left:windowwidth});
    currentView.$el.css({position:'absolute',width:windowwidth,left:'0px'});

    nextView.$el.animate({translate: '-'+windowwidth+',0px'}, speed, RF.Easing.quickO);
    currentView.$el.animate({translate: '-'+windowwidth+',0px'}, speed, RF.Easing.quickO, function(){

        if (clearStack) {
            _.each(_.initial(self.subViews), function( view ){
                 view.close();
            });
            self.subViews.length = 0;
            self.subViews.push(nextView);
        }

    });

break;

I'll try to write up a decent gist of the whole system and post here in the next week or so.

Answer 3

based on one of Derick Bailey's examples:

 model = new Model({_id:id})               
   var fetched = model.fetch();

  // wait for the model to be fetched
  $.when(fetched).then(function(){

     view = new View({model:model})                               
     app.content.show(view)     
  });

Answer 4

Both answers above work.
Here's yet another way which I prefer to use (feels more backboney).

Bind the view directly to the model
When the model is done being fetched, the function you specify will run. This can be done with models or collections.

var Model = Backbone.Model.extend({});
var model = new Model();
model.fetch();

var View = Marionette.ItemView.extend({
    model:model,
    initialize: function(){
        this.model.bind("sync", this.render, this);// this.render can be replaced
    }                                              // with your own function
});                               

app.region.show(new View);                                           

This also enables you to fetch whenever you want.