Bcakbone.js error in collection fetch

Question

I'm trying a simple backbone.js application. And getting error on doing collections fetch and not able to figure out why. Any pointers to check for will be helpful.

1- My backend is java based.

2- here are my model and collection

var lesson = Backbone.Model.extend
({
defaults : 
    {
        lessonId: '',
        lessonName: '',
        subject: '',
        textBook: '',
    },

    initialize: function()
    {}
   });

var lessonsCollection = Backbone.Collection.extend
({
model: lesson,
url: "/lessons?subject=Math&class=5",

initialize : function(){
    //var items = this.fetch();
    //console.log(items);
}

});

3- The response produced from server on the data request is :

[
{"lessonId":"00000001","lessonName":"DemoFractions","subject":"Math","textBook":"Null"},
{"lessonId":"00000002","lessonName":"test ","subject":"Math","textBook":"test"}
]

4- My code to make fetch call looks like

var coll = new lessonsCollection();
coll.fetch(
        {
        success: function(){
           console.log("got data");
           } ,

         error: function(){
           console.log("error in getting data through rest");
           }
        }
    );

However everytime the fetch call is resulting in error. What is it that I'm missing in my code?

EDITED: Based on suggestion I'm now logging the response. My code looks like

     coll = new lessonsCollection; 
 coll.fetch(
         {    
               success: function(){
                     console.log("got data");
                     self.render() ; 
               } ,

       error: function(collection, response){
             console.log("error in getting data through rest");
             console.log("response text got ",response.responseText);
             console.log(response);
           }
         }     
        );

The console log appears like a js code to me.

error in getting data through rest response text got
({readyState:0, getResponseHeader:(function (e){var t;if(2===b){if(!c){c={};while(t=Tn.exec(a))c[t[1].toLowerCase()]=t[2]}t=c[e.toLowerCase()]}return null==t?null:t}), getAllResponseHeaders:(function (){return 2===b?a:null}), setRequestHeader:(function (e,t){var n=e.toLowerCase();return b||(e=v[n]=v[n]||e,y[e]=t),this}), overrideMimeType:(function (e){return b||(p.mimeType=e),this}), statusCode:(function (e){var t;if(e)if(2>b)for(t in e)m[t]=[m[t],e[t]];else C.always(e[C.status]);return this}), abort:(function (e){var t=e||w;return u&&u.abort(t),k(0,t),this}), state:(function (){return n}), always:(function (){return i.done(arguments).fail(arguments),this}), then:(function (){var e=arguments;return x.Deferred(function(n){x.each(t,function(t,o){var a=o[0],s=x.isFunction(e[t])&&e[t];i[o[1]](function(){var e=s&&s.apply(this,arguments);e&&x.isFunction(e.promise)?e.promise().done(n.resolve).fail(n.reject).progress(n.notify):na+"With"})}),e=null}).promise()}), promise:(function (e){return null!=e?x.extend(e,r):r}), pipe:(function (){var e=arguments;return x.Deferred(function(n){x.each(t,function(t,o){var a=o[0],s=x.isFunction(e[t])&&e[t];i[o[1]](function(){var e=s&&s.apply(this,arguments);e&&x.isFunction(e.promise)?e.promise().done(n.resolve).fail(n.reject).progress(n.notify):na+"With"})}),e=null}).promise()}), done:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), fail:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), progress:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), complete:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), success:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), error:(function (){if(l){var t=l.length;(function i(t){x.each(t,function(t,n){var r=x.type(n);"function"===r?e.unique&&p.has(n)||l.push(n):n&&n.length&&"string"!==r&&i(n)})})(arguments),n?o=l.length:r&&(s=t,c(r))}return this}), responseText:"", status:0, statusText:"error"})

thanks

Peter Lyons Peter Lyons · Accepted Answer · 2013-08-07T19:31:16

Well, the specific error you are getting back in the response would be really helpful for us to see, but you need at least to set idAttribute on your Lesson model.

var Lesson = Backbone.Model.extend({
  idAttribute: 'lessonId',
  defaults: {
    lessonId: '',
    lessonName: '',
    subject: '',
    textBook: ''
  }
});

See if that fixes it. Otherwise, log the response:

   error: function(collection, response){
     console.log("error in getting data through rest", response);
   }

Bcakbone.js error in collection fetch

1 Answers