I have a similar challenge to this post: Batch insert/update with entity framework from a couple years ago, I was hoping that the story may have changed since then.
In short, I am running a RESTful service, and as such I'd like a PUT to be document-oriented and take an object along with a collection of child elements in. The child elements have a unique string that I can use for determining existence.
Unlike the referenced poster, I don't have a query requirement; all I want to do is be able to take in a collection of my child elements and perform an insert on the child table for any that aren't already there, and an insert or delete on the many-to-many table to account for the current state of the collection. Ideally, with some efficiency. I realize that I might end up doing this as a sproc, I just wanted to see if there's an EF-native way that works first.