Database scaffolding produces empty method call and no ValueGeneratedOn*() call when using datetime/timestamp columns

[Slushnas]

Steps to reproduce

Create the table:

create table TimestampTable(
    Id int not null,
    Ts timestamp default '0000-00-00 00:00:00' on update CURRENT_TIMESTAMP,
    Dt datetime default '0000-00-00 00:00:00' on update CURRENT_TIMESTAMP,
    primary key (Id)
);

Run the scaffolder:

dotnet ef dbcontext scaffold 'ConnectionString' Pomelo.EntityFrameworkCore.MySql -o Test

The issue

The scaffolder produces the following:

protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<TimestampTable>(entity =>
            {
                entity.Property(e => e.Id).HasColumnType("int(11)");

                entity.Property(e => e.Dt)
                    .HasColumnType("datetime")
                    .HasDefaultValueSql("'0000-00-00 00:00:00'")
                    .();

                entity.Property(e => e.Ts)
                    .HasColumnType("timestamp")
                    .HasDefaultValueSql("'0000-00-00 00:00:00'")
                    .();
            });

            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

Issue 1: The default value strings have added single quotes which may be a problem but that behavior is already detailed in Issue #703.

Issue 2: The datetime and timestamp properties have an empty method call .() appended which causes build errors.

Issue 3: I would expect the scaffolder to append .ValueGeneratedOnUpdate() or .ValueGeneratedOnAddOrUpdate() to the property definition based on the syntax here: https://dev.mysql.com/doc/refman/8.0/en/timestamp-initialization.html. Perhaps there is a bug with this functionality that is causing issue 2?

Also - I'm not sure if the OnModelCreatingPartial() method is supposed to exist here or not as it doesn't appear to be used.

Further technical details

MySQL version: 10.1.41-MariaDB-0ubuntu0.18.04.1
Operating system: Ubuntu 18.04
Pomelo.EntityFrameworkCore.MySql version: 3.0.0-rc1.final
Microsoft.AspNetCore.App version: 3.0

[lauxjpn]

Issue 2 & 3 are likely to be related.

Also - I'm not sure if the OnModelCreatingPartial() method is supposed to exist here or not as it doesn't appear to be used.

The point of this method is, that you can implement it in a partial class. If you implement it, it will be called as part of OnModelCreating(). Otherwise, it will not be called.

[Slushnas]

Thanks, I had wondered if it was there as a placeholder in case it was needed.

[lauxjpn]

Issue 1 is not an issue, but the correct behavior. Issue #703 is just a special case, where single quotes are invalid.

For issue 2/3, I opened dotnet/efcore#18579 upstream, as this seems to be a bug in EF Core.

In your specific case, we can actually solve this by safely applying ValueGenerated.OnAddOrUpdate (because you also specify a default value), which will be handled by EF Core.

[mguinness]

The upstream bug is fixed and will be in the 3.1 release.