Completely remove attribute from Backbone.js model

Question

I am trying to totally remove an attribute from a backbone model. The model is being sent to an API that isn't very flexible, and it will break if I send additional attributes over the ones I'm supposed to send, so I need to remove an attribute so it no longer exists.

I tried model.unset, from this question, but when I print out the object the attribute I'm trying to remove is still listed, just with a value of null.

I need the attribute to be completely gone.

My basic structure is:

model.unset("AttrName", "silent");

Solution 1

The problem is that you're using the parameters for unset incorrectly. "Silent" should be a part of an options hash, not a separate parameter. This works:

model.unset("AttrName", { silent: true });

---

The reason for the strange behavior can be seen from the annotated source:

unset: function(attr, options) {
  (options || (options = {})).unset = true;
  return this.set(attr, null, options);
},

The unset method assumes that its options parameter is an object, and attempts to either create or modify it, then passes it on to the set method. If you pass a string instead, then the inadvertent effect of the code is to set the attribute to null, rather than to unset it.

Solution 2

Override the toJSON method of your model and only include the attributes you wish to send.

Updated: (added code sample)

When extending the model, add a toJSON function and return an object with the desired attributes:

{
    toJSON : function() {
        return {
            name: this.get('name'),
            age: this.get('age'),
            phoneNumber: this.get('phoneNumber')
        };
    }
}

Comments

[FrizbeeFanatic14]

If I change the options to be a hash like that it triggers a change event, which is exactly what I'm trying to avoid with the silent option.

[FrizbeeFanatic14]

I'm pretty new to Backbone - how exactly would I go about that?

[McGarnagle]

@FrizbeeFanatic14 something else is wrong -- if you use that syntax, it shouldn't raise a change event (I just tested this).

[FrizbeeFanatic14]

You're right, it was something else calling that event. Thanks.