Models "steal" each others collections

[Sephi-Chan]

I develop an app where users have vehicles (with a HasMany relationship).
On the user profile page, I display the profile of the given user and I list his vehicles.
But on the sidebar, I also list the vehicles of the current user.

The problem occurs when the user displays his own profile page, the collection of vehicles is only in one object (the last instantiated). Example:

currentUser = Store.get('currentUser')
console.log currentUser.get('vehicles').length // 4

user = new Models.User(Seeds.user)
console.log user.get('vehicles').length // 4
console.log currentUser.get('vehicles').length // 0

The result for me is that the vehicles are in the page content but not in the sidebar anymore.
How can I fix that?

Note that I have to instantiate this second user since its attributes are not the exactly the same as the current user object (some private attributes are not in the "public" version of the user).

[DouweM]

This is because for Backbone-relational to work properly there can only be one model of a specific type with a specific ID alive at any time.

For your specific case, you're going to have to use a bit of code inspired by Backbone.HasOne#findRelated:

user = Backbone.Relational.store.find( Models.User, Seeds.user );

if ( user ) {
    user.set( Seeds.user );
}
else {
    user = new Models.User( Seeds.user );
}

Because this seems like a common practice, it might be an idea to add a .findOrBuild() method on Backbone.RelationalModel, that does exactly that. What do you think, @PaulUithol?

[Sephi-Chan]

Thanks @DouweM, I'll try that. :)

[PaulUithol]

I guess that could work, as a method on the constructor. Would be nice if that could replace Relation.createModel right away.

[DouweM]

It probably can't replace Relation.createModel right away, as that method checks for this.options.createModels being true, which .findOrBuild() shouldn't do.

[PaulUithol]

Well, I've already got something for that. It can't check it directly of course, but it can take an option to create new instances or not.

[DouweM]

Fair enough.