Question

Assume:

BaseEntity
ChildEntity : BaseEntity

The problem is getting the base entities with an efficient way. What I know that works is this type of query:

var results = context.BaseEntities.Where(entity => !(entity is ChildEntity) );

However this is very prone to breaking, as simply adding another extension to BaseEntity, like ChildEntityTwo : BaseEntity will break the query (query will include BaseEntity and ChildEntityTwo types.

Also, I havent had the chance to profile it yet but I suspect the query downloads all the entities and filters them in memory, but I could be wrong with this one.

Note that the solution context.BaseEntities.OfType<BaseEntities>() will actually include and download all the entities as well! It only works when you need an endpoint class, like ChildEntityTwo

Answer 1

ESQL offers OFTYPE ONLY operator for this purpose but that operator doesn’t have any equivalent in Linq. You can use this workaround to build OFTYPE ONLY for Linq.