Entity Framework 6.1 Updating a Subset of a Record

Question

I have a view model that encapsulates only some of the database model properties. These properties contained by the view model are the only properties I want to update

Answer 1

(Edited for clarity)

The context must have a complete copy of the object to enforce business rules. This can only happen if the attached object has all the necessary properties populated or the partial view is merged with a complete copy before updating.

I believe that what you want to do is conceptually impossible: doing updates like this will require either a preserved pre-change copy, or two queries to the database because the business layer needs a full copy of the object for validation.