Entity Framework - Add Navigation Property Manually

I generated an Entity Framework Model (4.0) from my database. I did not design the database and do not have any control over the schema, but there are a few tables that do not have foreign key constraints defined, but there is an implicit relationship defined.

For example:

I have a table called People that has the following columns: GenderID RaceID

There are tables for both Gender and Race but there is no foreign key in the People table.

When I imported the model it did not add Navigation Properties for these relationships. I tried to add it manually but From Role and To Role are disabled. I'm not sure how to add the relationship myself. How do I do this?

Solution 1:

Yup - it's not that straightforward.

Here's what you do:

1 - Right click on the designer, Add -> Association

2 - Setup the association and cardinalities (People *..1 Gender, People *..1 Race)

3 - Go into the Model Browser -> Associations

4 - Right click on your newly created associations, click Properties

5 - Here you need to setup the endpoints for the key and cascade options. Make sure you get the endpoints correct. You can also setup a referential constraint here for your implicit navigational property.

6 - Map the navigational property to the relevant tables/fields.

7 - Validate your model, cross your fingers.

Hope this helps.

Solution 2:

I came across this blog post which proposes the following solution, which worked great for me (unfortunately I could not get RPM1984's to work in my situation).

1. Add an Association via designer background right click contextual menu
2. Set up your Association (be sure to uncheck creation of foreign key)
3. Right click on the association and choose Properties
4. Click on the ... button for Referential Constraint
5. Set up the relation between the keys within
6. Verify (from the designer contextual menu)
7. ???
8. Profit!