Model Implied Relationships & Serialization = Too Much Recursion?

Model Implied Relationships & Serialization = Too Much Recursion?

in jQueryMX • Model • 7 years ago

I've got some CanJS models roughly arranged like so:

User = can.Model({
attributes: {
activities: 'Activity.models',
}
});
Activity = can.Model({
attributes: {
user: 'User.model',
}
});

My API sends back user IDs with activities and it looks like CanJS wires up the relationship automatically. Example:

foo = User.new({id: "123"})

and then if

bar = Activity.findOne("456")

returns an activity with { ... user: {id: "123"} } CanJS will ensure that:

bar.user === foo

That's neat. But when I do bar.serialize() CanJS tries to serialize the activity, which tries to serialize the user, which descends into the activity again and on and on...

What's the right way to handle these circular relationships when serializing?

Replies(2)

onyxrev

Re: Model Implied Relationships & Serialization = Too Much Recursion?

7 years ago

I see that one can overload serialize on the model, but this is of limited use because calling _super() will trigger the recursion.

onyxrev

Re: Model Implied Relationships & Serialization = Too Much Recursion?

7 years ago

Here's where I'm at. I've set up a base model to inherit from with a static property called "serialization_keys" that is a list of attributes to include in serialization. Then I created my own serialization method:

serialize: function() {
var self = this;
var serialized = {};
var attribute_keys = this.constructor.keys(this);
var serialization_white_list = this.constructor.serialization_keys || attribute_keys;
$.each(attribute_keys, function(i, attr_key){
if (serialization_white_list.indexOf(attr_key) === -1) return true;
serialized[attr_key] = self.attr(attr_key);
});
return this._super.apply(new this.constructor(serialized), arguments);
}

Basically if serialization_keys is not defined it serializes everything. if it is defined, it skips anything not in the list. It creates a new temporary model instance and serializes it with only the necessary keys.

This allows me to specify that the user should be skipped when serializing an activity.

Not ideal but it seems to do the trick. Anyone have a better solution?

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