Understanding custom collections

In my experience, collections are highly random. Even simple usage makes no sense to me.

class OtherModel extends bookshelf.Model {
  get tableName () { return 'other_models' }
}

class MyModel extends bookshelf.Model {
  get tableName () { return 'my_models' }

  otherRelation () {
    return this.hasMany(OtherModel)
  }
}

class MyOtherCollection extends bookshelf.Collection {
  get model () { return OtherModel }
}

MyModel
  .forge({ id: 1 })
  .otherRelation()
  .fetch()
  .then((myOtherModels) => {
    console.log(myOtherModels instanceof bookshelf.Collection) // true
    console.log(myOtherModels instanceof MyOtherCollection) // false
  })

My question is, is this behaviour intended? If yes, I’m quite lost on how I should reason about collections in general.

Am I perhaps going about this wrong and completely missed a core principle?

[ricardograca]

Interesting. With #1806 the registry plugin will be promoted to core, so this feature will be built-in. It would be a good idea to add these instruction on how to create a custom reusable collection to a guide explaining the whole process.

[fl0w]

If anyone else stumbles upon this, here’s the correct way to register a custom collection when using the registry plugin:

class MyModels extends bookshelf.Collection {
  get model () {
    return MyModel
  }
}
class MyModel extends bookshelf.Model {
  static collection (...args) {
    return new MyModels(...args)
  }
}

bookshelf.collection('MyModels', MyModels) // This is what I previously forgot
bookshelf.model('User', User)

After this bootstrap everything runs as expected currently (except that Collection.fetched event isn’t fired on a relation call as I would have expected - but Collection.fetching does).