Guid is empty with newsequentialid() and EF database first

Question

I'm working on a website using EF 4.1 and database first. I'm also using aspnet tables, particularly aspnet_Users which is using Guid as a primary key. Consequently, my custom User table also has a Guid as primary key, which is a foreign key to the aspnet_Users id.

Recently, I read that using Guid as primary keys was a bad idea unless using newsequentialid().

With Sql Server Management Studio I have updated all my primary keys' default value to newsequentialid(), and set StoreGeneratedPattern to Identity in my edmx designer.

However, whenever I try to add an objet (for example Item which has a Guid primary key), its id remains empty (all 0) in database.

public void CreateItem()
{
    using (var uof = new UnitOfWork())
    {
        Item item = new Item();
        itemRepo.Add(item);
        uof.Commit();
    }
}

And the add method :

public class RepositoryBase<TObject> where TObject : IEntity
{
    protected CavalenaEntities entities
    {
        get { return UnitOfWork.Current.Context; }
    }

    public void Add(TObject entity)
    {
        entities.Entry(entity).State = System.Data.EntityState.Added;
    }
}

Did I forget something ? Although I set the default value for the primary keys of my database, their Default Value property in edmx designer is still None. Is it normal ?

Another solution would be to use int as primary keys instead of Guid but then how could I do the link between my custom User table and aspnet_Users, which uses Guid ?

Thanks a lot !

Answer 1

Using NEWID() is absolutely OK unless you need sequence identifiers. But then you probably don't need Guid/uniqueidentifier, you can use int or bigint and identity or SQL sequence object.