[Migrations] EFCore doesn't respect IsRowVersion for properties with conversion to byte[]

[akamud]

When using an entity with a property with a type different from byte[] that is configured as a RowVersion, the migration generated doesn't specify that the column should be a rowversion, and instead just creates a byte array column on SQL Server. This happens even if the property has a valid conversion to byte[] (like ulong).

Steps to reproduce

This is the simplest repro I could create. You can recreate the migration to verify the problem.

This entity:

public class Entity
{
    public int Id { get; set; }
    public ulong RowVersion { get; set; }
}

With this configuration:

modelBuilder.Entity<Entity>()
    .Property(x => x.RowVersion)
    .IsRowVersion()
    .HasConversion<byte[]>();

Will not generate a migration that indicates that the RowVersion column should be a rowversion from SQLServer.

This is the relevant part from the generated migration:

            migrationBuilder.CreateTable(
                name: "Entities",
                columns: table => new
                {
                    // notice the missing rowVersion: true
                    RowVersion = table.Column<byte[]>(nullable: false)
                }

If you change the property to be a byte[] in the C# mapped entity, it starts generating the migration correctly again.
I believe the problem is this check, since EF core corrctly understands the ulong to byte[] conversion and works perfectly when querying or in CRUD operations, I believe this check shouldn't ignore the IsRowVersion mapping info based on the assumption that only a property with a byte[] type is valid.

Properties with a valid conversion to byte[] should also be considered when setting the rowVersion flag.

Workaround

As a workaround, we are using the .ColumnType("rowversion"), but this is not valid in all scenarios, since if you decide to "fix" the issue making the property a byte[], EF Core won't understand something has changed, generating an empty migration. So if you apply a faulted migration, undoing the mistake is not as simple as generating a new migration from ef core.

Further technical details

EF Core version: 3.1.1. But confirmed to happend at least since 2.1.14
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 3.1
Operating system: Windows and Mac
IDE: Visual Studio 2019 16.3.1

[ajcvickers]

@akamud Thanks for the detailed issue; I think this is essentially a duplicate of #12434 but we will revisit the priority.

but this is not valid in all scenarios, since if you decide to "fix" the issue making the property a byte[], EF Core won't understand something has changed, generating an empty migration.

I don't think EF should be creating an empty migration here. Can you file a new issue for this?

[ajcvickers]

From team discussion: Made #12434 a stretch goal for 5.0 and closing this as a duplicate.