No way to set relationshipKeyPathsForPrefetching

[johnclayton]

I am wanting to include this attribute in a FetchRequest so I can construct a FetchRequestController with it, but since there is no property for it on FetchRequest, nor a constructor that would take an NSFetchRequest to represent the internal state there doesn't seem to be a way to do this using extensions.

Was thinking something like this syntax would work:

func include(relationships: String...) -> FetchRequest<Entity>

And in a Query:

func include(relationships: String...) -> Query<Entity>

Am I missing an avenue to do this external to the framework?