How to add an EF6 Association to a Candidate Key / Unique Key which is not the Primary Key?

Question

Using Schema First, I have a database structure, as so

ExternalDataItems
---
edataitem_id   PK -- surrogate         


        

Answer 1

Looks like "missing important feature"

.. The Entity Framework currently only supports basing referential constraints on primary keys and does not have a notion of a unique constraint.

You can remove foreign key in DB scheme and use LINQ to join tables:

from item in ExternalDataItems
join map in ExternalMaps on item.datahash = map.ext_datahash
select new { item.edataitem_id, map.emap_id };

Also you can create the VIEW with these joined tables and use the one.