Entity Framework - Model First: One-to-One relationship

If you’re doing Model First with Entity Framework you may run into a scenario where you want to design a 1-to-1 relationship, but also have a foreign key be available on your entity. The default behavior in Entity Framework when doing a 1-to-1 relationship (with Model First), or 1-to-0..1 relationship, is to create a foreign key on the 0..1 side of the association but hide the foreign key. A better approach is this:

• Start a new model
• Add the entity that goes on the 1 side of the association, give it a primary key of type integer. Make sure the StoreGeneratedPattern property is set to Identity.
• Add the entity that goes on the 0..1 side of the assocation, name the primary key as you would a foreign key, make it of type integer. Make sure the StoreGeneratedPattern property is set to None.
  
• Click on the 1 entity and add an association, make it a 1-to-0..1, example:
  
• Double click the association and set a referential constraint.
  
• Now you’re ready to generate your database schema.