Question

collection and view in back bone

var studentmodel = Backbone.Model.extend();

    var studentcollection = Backbone.Collection.extend({
model : studentmodel,
url : 'http://localhost/bb/data.JSON',
parse : function(response){
    //console.log(response.data);
    return response.data;
    //return response;
},
  });



var studentlistview = Backbone.View.extend({
    tagName : "ul",
    className : "studentlistul",
    initialize : function(){
        this.model.bind("reset", this.checkEvent,this);
        this.model.bind("add", this.checkEvent,this);
    },
      checkEvent : function(){

        $(this.el).html("");

    _.each(this.model.models, function(student){

    $(this.el).append(new studentListItemView({ model : student}).render2().el);
    }, this);

    $('#studentlistdiv').html($(this.el));

    return this;

}
});

and try to add items to this model and its work, my question is that inside render fn how can i get the event type while this.model.bind(“add”, this.checkEvent,this) this evt fire. inside checkEvent how can i get the type of event ie which one fired add or reset. this is my question plz help me

Answer 1

There is no reliable way for a Backbone event handler to know what event triggered it. Instead of doing this:

this.model.bind("reset", this.checkEvent, this);
this.model.bind("add",   this.checkEvent, this);

you should have separate handlers for each desired action:

// A reset generally means that you want to redraw the whole thing.
this.model.bind("reset", this.render, this);

// If one model is added then you usually just want to render the
// the new one.
this.model.bind("add", this.render_one, this);

and then your render would look sort of like this:

this.$el.empty();
this.collection.each(this.render_one, this);
return this;

A couple extra things while I’m here:

1. Backbone views already have a jQuery version of their this.el in this.$el so there’s no need to $(this.el), just use this.$el.
2. Backbone views handle the collection option the same way they handle model. So if you new View({ collection: c }) then the view will automatically have this.collection. If you have a collection, use collection and if you have a model, use model; using accurate names is less confusing.
3. Backbone collections have a bunch of Underscore methods already mixed in so you can say this.collection.each(...) instead of _(this.collection.models, ...).