c# - LINQ Include on a one-to-many with .Where() not working?

Question

I'm trying to query Users including each user's Interests, but only where an Interest meets certain criteria:

  return db.Users.Include(u => u.Interests.Where(s => s.TenantId == tenantId))

But I get an error:

The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operator for collection navigation properties.

I played with the idea of pushing the .Where outside, but haven't been able to get it working.

Answer 1

Try this:

return db.Users.Include("Interests").Where(u => u.Interests.Any(i => i.TenantId == tenantId));

This causes the users to be loaded, but only where the tenantId matches. The Interests related entities will be eager loaded for those users when the query executes.