javascript - Backbone Model custom URL -

i unsure how call , pass variable model call custom url.

the url trying call is:

http://localhost:8080/sims/resource/class/teacher/{id} 

id not class id teacher id.

in main.js unsure how pass parameter model , use in model. how go doing ?

model:

window.class = backbone.model.extend({     urlroot: "http://localhost:8080/sims/resource/class/teacher",     defaults: {           "id": null,         "grade":  "",         "year": "",             "tname": "",             "sname": ""       },        parse: function(response){            response.id = response.idclass;       } ,        tojson: function(){       } });  window.classcollection = backbone.collection.extend({     model: class,     url: "http://localhost:8080/sims/resource/class/teacher",          parse: function(response){           (var i=0; i<response.length; i++)            {                response.id = response.idclass;            }            return response ;         } }); 

main.js

routes: {  "sidebar/:id": "sidebar" },  sidebar: function(){     this.classlist = new classcollection();      this.classlist.fetch({success: function() {         $('#sidebar-collapse').html( new teachersidebarview({model: app.classlist}).render().el );         if (callback) callback();     }}); }, 

view

window.teachersidebarview = backbone.view.extend({     tagname:'ul',      initialize:function () {         this.templatea = _.template(tpl.get(sidebara));         this.templateb = _.template(tpl.get(sidebarb));         this.model.bind("reset", this.render, this);         var self = this;          this.model.bind("add", function (class) {             $(self.el).append(new teachersidebaritemview({model:class}).render().el);         });     },      render:function (eventname) {          $(this.el).html(this.templatea());         _.each(this.model.models, function (class) {             $(this.el).append(new teachersidebaritemview({model:class}).render().el);         }, this);          $(this.el).append(this.templateb());         return this;     } });  window.teachersidebaritemview = backbone.view.extend({     tagname:"li",      initialize:function () {         this.template = _.template(tpl.get('sidebarc'));         this.model.bind("change", this.render, this);         this.model.bind("destroy", this.close, this);     },      render:function (eventname) {         $(this.el).html(this.template(this.model.attributes));         return this;     } }); 

the url property of model can function concatenates , returns base url , dynamic id property. this:

baseurl: "http://localhost:8080/sims/resource/class/teacher", url: function() { return this.baseurl + '/' + this.id; },