This is a question best suited to the Glorp mailing list (which I'm cc'ing in this email).
What you need is an HorizontalTypeResolver, and define a common class as the ancestor for both of your classes. You'll have to define a descriptor for it, and you will use it to reference the "parent" of these (e.g. AbstractQuestion). So in your Glorp Descriptor you'll end up with something like: QuestionDescriptorSystem>>#typeResolverForAbstractQuestion ^(HorizontalTypeResolver forRootClass: AbstractQuestion) QuestionDescriptorSystem>>#descriptorForAbstractQuestion: aDescriptor "..." (self typeResolverFor: AbstractQuestion) register: aDescriptor abstract: true. QuestionDescriptorSystem>>#descriptorForQuestion: aDescriptor "..." (self typeResolverFor: AbstractQuestion) register: aDescriptor. QuestionDescriptorSystem>>#descriptorForQuestionGroup: aDescriptor "..." (self typeResolverFor: AbstractQuestion) register: aDescriptor. Then classModelForSection: aClassModel aClassModel newAttributeNamed: #questions collectionOf: AbstractQuestion I don't know about your model, but if both classes work polymorphically and have a common semantic root (it is "Question"), it is hard for me to see why they don't have a common ancestor. Disclaimer: the above code was written without testing it, based on my memory only :) Regards, Esteban A. Maringolo 2018-03-29 11:43 GMT-03:00 Alejandro Infante <alejandroinfant...@gmail.com>: > Hi guys! > > I’m trying to use GLORP and I’m having problems defining the class model for > a class which has an instance variable which is a collection of instances of > two different classes: > > I have 3 classes named: { Section . Question . QuestionGroup } and I have > problems for specifying the glorp class model for Section. > Object subclass: #Section > instanceVariableNames: ‘questions ...' > classVariableNames: '' > > The thing is that #questions instance variable is a collection of Question > AND QuestionGroup. They have polymorphic behavior, but they have not a common > superclass (besides Object). > > How does my class model should look like? > > classModelForSection: aClassModel > ... > aClassModel newAttributeNamed: #questions collectionOf: ****?. > > > Thanks for the help! > Cheers, > Alejandro