How to avoid the N+1 problem?

[gebekov]

Hi! Thanks for the great library 🙂!

I have a question:
Is there a way to avoid N+1 problems when mapping collections from DTO using transformers/providers (e.g. I keep identifiers in the DTOs and I want them to be loaded from the DB)? Unfortunately I couldn't find a clear answer to my question in the documentation.

The most obvious solution is to retrieve the required objects from the database in advance, before mapping, and pass them to the context. And then pass those objects from the context, but it seems to me that this is not a good solution. Is there another way to map collections?

Thanks in advance!

[damienalexandre]

Doctrine EntityManager is capable of that, so it could be possible to:

• craft a query to fetch all necessary entities at once
• use find(ID) in the transformer, and let the EntityManager returns the already known objects

Anyway, the question is, should we expect the automapper to deal with that?