Repository pattern - how to correctly handle JOINs and complex queries?

Question

I have a problem with Repository pattern - how to perform JOIN operations between several repositories. In this project, we use MVC, EF, DDD. I\'m aware that this kind of questi

Answer 1

1. means leaking persistence into application - antipattern, spaghetti-code.
2. how it differs from (1) exactly? Still the same issue.
3. a bit closer...
4. Use Query Object pattern. Encapsulate your complex query in a task-based object that resides alongside repositories. It can return DTOs optimized for view rather than domain objects.
5. Relying heavily on QO will lead you to an architecture called CQRS - Command-Query Responsibility Segregation.

One more thing. There is not 1:1 match for entity:repo. Only Aggregates should have a repository, not every single entity.