Entity Framework CTP 4. "Cannot insert the value NULL into column" - Even though there is no NULL value

Im using EF CTP 4. I have a simple console app (for testing purposes) that is using EF to insert some data into a SQL database.

I have come to a problem where by upon inserting the item

using(var context = GetContext())
{
   BOB b = new BOB();
   b.Id = 1;

   context.Bobs.Add(b);
   context.SaveChanges();
}

It throws the error: {"Cannot insert the value NULL into column 'Id', table 'TestDB.dbo.BOB'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated."}

The Table just has 1 field of Id int NOT NULL which is the primary key and is not an auto incremented Id.

On the creation of the DataContext I have this configuration, which yes does get fired.

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.Entity<BOB>().HasKey(b => b.Id);
    builder.Entity<BOB>().MapSingleType().ToTable("BOB");
}

I have also pre-populated this table and then through the debugger been able to via watch load up this BOB object... so I am really stumped, as for being able to load up my BOB shows that all is right... however upon inserting a new one it crashes...

Solution 1:

i have the same issue here and it's really an ugly solution.

 [Key]
public Int64 PolicyID { get; set; }

this is NOT an auto generated number

then i hit the same error.

EF Code First CTP5

after apply this:

 [Key]
 [DatabaseGenerated(DatabaseGeneratedOption.None)]
 public Int64 PolicyID { get; set; }

then it will work.

Solution 2:

I'm using EF 4.1, Model First and came across this problem. Here's how I solved it:

When using the Model Designer surface, when you create an Entity, you have to define a Key property, it defaults to Id, int32.

In my situation, I've chosen to use Guids for the Id, so I'd switch the int32 to Guid. But if you examine this Id after you create the entity, I saw that the Id's 'StoreGeneratedPattern' had 'identity' selected. At first I didn't think that was a problem, but when I examined the SQL being used to insert into the database, it was a bit weird in that it wasn't sending my Id. Frustrating!

But once I went back and changed the 'StoreGeneratedPattern' from 'identity' to 'none', regenerated the db and rebuilt the project, this strange message stopped happening:

Cannot insert the value NULL into column 'Id', table 'TestDB.dbo.BOB'; column does not allow nulls. INSERT fails. The statement has been terminated.

FYI - upon viewing the sql some more it seems that if you have identity chosen for StoreGeneratedPattern, the EF saves the object to the db (sans Id), then immediately fetches back the identity and saves that back to your object. i.e. this choice for StoreGeneratedPattern relies on the db to generate your Id, NOT your code!

Solution 3:

Have you tried explicitly specifying the StoreGeneratedPattern?

modelBuilder.Entity<BOB>()
    .HasKey(p => p.Id)
        .Property(p => p.Id)
            .StoreGeneratedPattern = StoreGeneratedPattern.None;

builder.Entity<BOB>().MapSingleType().ToTable("BOB");