Violation of Liskov Substitution Principle

https://github.com/graphql-python/graphql-core/blob/3ba7f9218bca7a039b109b103cf57b1511d970c7/graphql/execution/executor.py#L704

Above referenced line violates Liskov Substitution Principle when used with at least Graphene-Django and the underlying model is itself a subclass of aDjangoObjectType.Meta.model class.

A popular variant of this violation is use of django-polymorphic, which is quite prevalent. However, we're talking basic Python here.

Start at graphql/execution/executor.py#L704 and read the surrounding execution logic to understand how subclassed Django models are handled. Reproduce the reported behavior with Graphene-Django and, if available, django-polymorphic, then identify the expected substitution behavior and add regression coverage. Done means the reported subclass scenario works without breaking existing execution behavior.

Vom Indexierungsmodell aus dem Issue-Text verfasst.