Backbone save does not send undefined attributes

Question

I have the following code :

     this.myModel.save(this.patchAttributes, {
        //Ignored if saving new record; will send a POST
        patch: true,
        success: function() {
               success();
            }
        },
        error: function() {
                error();
        }
    });

If my patchAttributes has an entry like fieldName:undefined, I cannot see it in the request headers of the PATCH request.

Answer 1

That's because Backbone is JSON.stringifying the data before sending it. The JSON spec does not allow the undefined token. Therefore any properties that are undefined will be omitted from the JSON string.

JSON.stringify({ foo: undefined });
// The output is "{}"

Instead of undefined you should use null which is part of the JSON spec:

JSON.stringify({ foo: null });
// The output is "{"foo":null}"