Question

I am doing entity framework (v 5) code first migrations, on an MVC 4 application. I would like to add a unique constraint at the database level.

I know this can be done when creating the table, but I already have a table.
http://msdn.microsoft.com/en-US/data/jj591621

I have tried the following, marked as answer answer: Unique constraint with EFCodeFirst and SqlCe4

My database context differes slightly, I supply the connection name is as follows

public AppDatabaseContext() : base("MyConnectionDBContext")

When I use the Package Management Console to update the database, the overridden seed method is not called:

protected override void Seed(AppDatabaseContext context)

I have also tried the following: http://romiller.com/2010/07/31/ef-ctp4-tips-tricks-running-additional-ddl/

I did not use a nested class, this is because it seemed as if I had to registere the initializer via the app.config. I could not get it working while initializing it in code. The InitializeDatabase is called, but the following condition is never true:

(!context.Database.Exists() || !context.Database.ModelMatchesDatabase())

This is because this happens after the migrations have been run…

I also tried this at one stage: Unique Constraint in Entity Framework Code First, it was the same problem as before, this condition was never returning true.

Ideally, I would like to include some standard SQL in my migration file. Is there a way to do that? If not, where can I see how to achieve this with using code first migrations?

Thanks!

UPDATE:

Is there any reason why I can’t use the SQL function?

 public override void Up()
 {
        AddColumn("Posts", "Abstract", c => c.String());

        Sql("UPDATE Posts SET Abstract = LEFT(Content, 100) WHERE Abstract IS NULL");
 }

Obviously using the correct SQL…

Answer 1

With code first migrations, I’ve just used this in the Up() method to add a unique index on a single column:

CreateIndex(table: "Organisations", 
            column: "Name", 
            unique: true, // unique index
            name: "MyIndex");

…and then in the Down() method:

DropIndex(table: "Organisations", 
          name: "MyIndex");

Is that what you’re after?