c# - IDENTITY_INSERT during seeding with EntityFramework 6 Code-First

Question

I have an entity that has an Auto-identity (int) column. As part of the data-seed I want to use specific identifier values for the "standard data" in my system, after that I want to have the database to sort out the id value.

So far I've been able to set the IDENTITY_INSERT to On as part of the insert batch, but Entity Framework does not generate an insert statement that include the Id. This makes sense as the model thinks the database should provide the value, but in this case I want to provide the value.

Model (pseudo code):

public class ReferenceThing
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id{get;set;}
    public string Name{get;set;}
}

public class Seeder
{
    public void Seed (DbContext context)
    {

        var myThing = new ReferenceThing
        {
            Id = 1,
            Name = "Thing with Id 1"
        };

        context.Set<ReferenceThing>.Add(myThing);

        context.Database.Connection.Open();
        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing ON")

        context.SaveChanges();  // <-- generates SQL INSERT statement
                                //     but without Id column value

        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing OFF")
    }
}

Anyone able to offer any insight or suggestions?

Answer 1

So I might have resolved this one by resorting to generating my own SQL insert statements that include the Id column. It feels like a terrible hack, but it works :-/

public class Seeder
{
    public void Seed (DbContext context)
    {

        var myThing = new ReferenceThing
        {
            Id = 1,
            Name = "Thing with Id 1"
        };

        context.Set<ReferenceThing>.Add(myThing);

        context.Database.Connection.Open();
        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing ON")

        // manually generate SQL & execute
        context.Database.ExecuteSqlCommand("INSERT ReferenceThing (Id, Name) " +
                                           "VALUES (@0, @1)", 
                                           myThing.Id, myThing.Name);

        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing OFF")
    }
}