CODEWITHSUNDEEP
javascriptbackbone.js
Erik
Erik

Reputation: 14770

Does backbonejs issues 'beforeChange' event?

I need to catch a "beforeChange" event, to prepare some stuff before a model's field changes. Does BackboneJS have something like this, or how could I accomplish something similar?

Upvotes: 2

Views: 191

Answers (1)

Lochlan
Lochlan

Reputation: 2796

There's no such thing as a "beforeChange" event—but there are a few ways I know of to accomplish a similar kind of thing.

1. Override model.set

The easiest thing to do is override model.set Example: http://jsfiddle.net/dkho4p2r/

var Foo = Backbone.Model.extend({
    set: function (attributes, options) {
        // do stuff here
        Backbone.Model.prototype.set.apply(this, arguments);
    }
});

2. model.validate

You also have access to model.validate, which—if you pass the validate: true option when calling model.set—is called before the model is actually changed.

Example: http://jsfiddle.net/dkho4p2r/1/

This probably isn't the best place to put arbitrary code, but it fits the requirement of occurring before the model's change event.

3. Process input before calling model.set

This may be the too-obvious answer you were looking to avoid, but you can always just "prepare some stuff" before calling set() on your model. Example: http://jsfiddle.net/dkho4p2r/2/

data = prepareSomeStuff(data);
model.set(data);

Upvotes: 2

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