CODEWITHSUNDEEP
javascriptjquerybackbone.jswebmarionette
David Haim
David Haim

Reputation: 26486

Backbone: Unable to override constructor

I'm trying to override Backbone.Model constructor with my own, in order to be able to pass my parameters from outside and not as a created-object.

here is my code: 

 var Video = Backbone.Model.extend({

constructor : function (videoUrl,imageSource,title,rating,description,starsImageSource){
    this.videoUrl = videoUrl;
    this.imageSource = imageSource;
    this.title = title;
    this.rating = rating;
    this.description = description;
    this.starsImageSource = starsImageSource;
    Backbone.Model.apply(this, arguments);
    }   

});

when trying to enter

new Video("www.yahoo","coins.jpg","Yahoo",4,"hhhh","5stars.png")

the following error appear: TypeError: invalid 'in' operand obj here is my includes:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.3.3/underscore-min.js" type="text/javascript"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/backbone.js/0.9.2/backbone-min.js" type="text/javascript"></script>
<script src="http://marionettejs.com/downloads/backbone.marionette.js" type="text/javascript"></script>

thanks!

Upvotes: 0

Views: 244

Answers (2)

u.k
u.k

Reputation: 3091

You have two things to correct:

  1. As mentioned before, prefer initialize over constructor

  2. Follow the API of new Model(attributes, options). The reason is backbone will take your first argument and treat is as as an attributes hash. in case its not an object, it may have unexpected behavior. In this case you may have something like:

var Video = Backbone.Model.extend({
  initialize : function (attrs, options){
    _.extend(this, _.pick(options, 'videoUrl', 'imageSource', 'title', 'rating', 'description', 'starsImageSource'));
  }
});

new Video(null, {
  videoUrl:"www.yahoo",
  imageSource: "coins.jpg",
  title: "Yahoo",
  rating: 4,
  description: "hhhh",
  starsImageSource: "5stars.png"
});

One question would be: why do you want to assign these parameters as first class parameters on the model object, and not as model attributes? In this case you don't need to add a constructor, just to pass the data:

new Video({
  videoUrl:"www.yahoo",
  imageSource: "coins.jpg",
  title: "Yahoo",
  rating: 4,
  description: "hhhh",
  starsImageSource: "5stars.png"
});

Upvotes: 2

hindmost
hindmost

Reputation: 7195

You don't need to override constructor.

The following code does exactly the same you need:

var Video = Backbone.Model.extend({

initialize : function (videoUrl,imageSource,title,rating,description,starsImageSource){
    this.videoUrl = videoUrl;
    this.imageSource = imageSource;
    this.title = title;
    this.rating = rating;
    this.description = description;
    this.starsImageSource = starsImageSource;
}   

});

Upvotes: 1

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