Baby steps to Backbone - step 2 - Validation

Feedback.js

var Feedback = Backbone.Model.extend({

    url: '/feedback',

    defaults: {
        'email': '',
        'website': '',
        'feedback': ''
    },

    validate: function (attrs) {
        var errors = [];

        if (!attrs.email) {
            errors.push({name: 'email', message: 'Please fill email field.'});
        }
        if (!attrs.feedback) {
            errors.push({name: 'feedback', message: 'Please fill feedback field.'});
        }

        return errors.length > 0 ? errors : false;
    }

});

FeedbackApp.js

$(function () {
    var model = new Feedback();
    var view = new FeedbackFormView ({model: model});
    
    $('#app').html(view.render().el);
});

FeedbackFormView.js

var FeedbackFormView = Backbone.View.extend({
   className: 'row',

    template: '\
        <form>\
            <legend>Share the feedback</legend>\
            <div class="control-group email">\
                <label>Email</label>\
                <input type="text" id="email" placeholder="Your email address...">\
                <span class="help-inline"></span>\
            </div>\
            <div class="control-group website">\
                <label>Web site</label>\
                <input type="text" id="website" placeholder="Your website...">\
                <span class="help-inline"></span>\
            </div>\
            <div class="control-group feedback">\
                <label>Feedback</label>\
                <textarea id="feedback" class="input-xxlarge" placeholder="Feedback text..." rows="6"></textarea>\
                <span class="help-inline"></span>\
            </div>\
            <button type="submit" id="submit" class="btn">Submit</button>\
        </form>\
    ',

    events: {
        'click #submit': 'submitClicked'
    },

    render: function () {
        this.$el.html(this.template);

        return this;
    },

    submitClicked: function (e) {
        e.preventDefault();

        var me = this;
        var options = {
            success: function () {
                me.hideErrors();
            },
            error: function (model, errors) {
                me.showErrors(errors);
            }
        };

        var feedback = {
            email: this.$('#email').val(),
            website:  this.$('#website').val(),
            feedback: this.$('#feedback').val()
        };

        this.model.save(feedback, options);
    },

    showErrors: function(errors) {
        _.each(errors, function (error) {
            var controlGroup = this.$('.' + error.name);
            controlGroup.addClass('error');
            controlGroup.find('.help-inline').text(error.message);
        }, this);
    },

    hideErrors: function () {
        this.$('.control-group').removeClass('error');
        this.$('.help-inline').text('');
    }
});

Use

Backbone.listenTo(model,'invalid',function(model,error,options){
       console.log(model,error,options);
   });

Where I need to put this code listenTo in the feedback app, I'm new to this technology, this one is not working with the current backbone version, can you please tell me where to put this new code I mean in which file? Thank you so much...

@shravanaz86 - a bit late to the party, but believe you could do the following:

this.model.on('invalid', function (model, error) {
     console.log(error);
}

this.model.save();