cannot update identity column in Entity Framework Core

Question

I've added a separate Identification to the AspNetUsers table called NumericId that will serve along with the GUID like ID that ASP has for default.

I've added the property as an additional property of the ApplicationUser class:

public class ApplicationUser : IdentityUser
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public virtual int NumericId { get; set; }
}

However, when I try to register, or update the user's details (that aren't even relevant to the numericId) I keep getting the error

SqlException: Cannot update identity column 'NumericId'.

which prevents any changes and in the end does not update the user (but it does register one, and Numeric Id is properly assigned on that part. But this is irrelevant)

Answer 1

Solution for asp.net core 3.1

modelBuilder.Entity<Type>().Property(u => u.Property).Metadata.SetAfterSaveBehavior(PropertySaveBehavior.Ignore);

Answer 2

Per the discussion on GitHub surrounding this issue, for EF Core 2.0 we needed to use both lines suggested in other posts.

for Entity framework core 2.0 , The "IsReadOnlyAfterSave" property is deprecated. Use following:

builder.Property(p => p.Id)
    .UseSqlServerIdentityColumn();

builder.Property(p => p.Id)
    .Metadata.AfterSaveBehavior = PropertySaveBehavior.Ignore;