Relationship to set of models?

[nils-werner]

Hi all,

I am trying to model the schema of an application that will likely require me to have relationships between one model and a set of other models, like an article that can contain a list of widgets. In dataclass-pseudocode:

@dataclass
class Image: ...

@dataclass
class Text: ...

@dataclass
class Article:
    title: str
    widgets: List[Image | Text]

I believe SQLalchemy would let me do that using Model inheritance, but I am not exactly sure. Would advanced alchemy let me do that, too, or is there something that I have to watch out for?

[provinzkraut]

Advanced alchemy is just a set of opinionated utilities for SQLAlchemy. There's nothing in there that would prevent you from using any SQLAlchemy feature you want.
So, yes.

[nils-werner]

OK cool, that's what I was hoping to hear! And just out of curiosity, are there any known quirks when doing something like this? My gut is telling me that it's quite close to the "there be dragons" area of an ORM 😄

[provinzkraut]

Nothing that comes from the SQLA side at least. Polymorphism has been a stable part of SQLA for ages and it works as it's supposed to.

So nothing from a technical side. The only thing I'd say is that, at least to me, this is usually a tell that something is wrong on the modelling side, and that maybe the way your DB schema / domain modelling is a bit off. There are legitimate use cases for this, but they are rare.

[nils-werner]

Yeah, totally... But I'm not sure how I should model it in a different way...