TPC migration attempts to drop nonexistent table for base type

[smstromb]

Reproducible with: https://github.com/smstromb/efcore-tpc-issue-reproducable

using Microsoft.EntityFrameworkCore;

public abstract class Animal
{
    public int Id { get; set; }
    public string Species { get; set; }
}
public class FarmAnimal : Animal
{
    public decimal Value { get; set; }
}
public abstract class Pet : Animal
{
    public string Name { get; set; }
}
public class Cat : Pet
{
    public string EducationLevel { get; set; }
}
public class Dog : Pet
{
    public string FavoriteToy { get; set; }
}

public class SomeDbContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseSqlite("Data Source=database.db")
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();

    public DbSet<Cat> Cats { get; set; }
    public DbSet<Dog> Dogs { get; set; }
    public DbSet<FarmAnimal> FarmAnimals { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Animal>().UseTpcMappingStrategy();
    }
}

Running dotnet ef migrations add Initial creates the expected sql schema with 3 tables for each concrete type but running a second migration, without any changes, results in a migration that attempts to drop Animal, a table that doesn't actually exist in the schema:

dotnet ef migrations add ExpectedToBeEmpty

using Microsoft.EntityFrameworkCore.Migrations;

#nullable disable

namespace DataModelPOC.Migrations
{
    /// <inheritdoc />
    public partial class ExpectedToBeEmpty : Migration
    {
        /// <inheritdoc />
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropTable(
                name: "Animal");
        }

        /// <inheritdoc />
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.CreateTable(
                name: "Animal",
                columns: table => new
                {
                    Id = table.Column<int>(type: "INTEGER", nullable: false)
                        .Annotation("Sqlite:Autoincrement", true),
                    Species = table.Column<string>(type: "TEXT", nullable: false)
                },
                constraints: table =>
                {
                    table.PrimaryKey("PK_Animal", x => x.Id);
                });
        }
    }
}

EF Core version: 7.0.0-preview.5.22302.2
Database provider: Microsoft.EntityFrameworkCore.Sqlite
Target framework: 7.0 Preview

[ajcvickers]

Note for triage: repros with latest daily build.

[pheuter]

@AndriySvyryd This still appears to be an issue, tested on Entity Framework Core .NET Command-line Tools 7.0.0-preview.7.22376.2

[AndriySvyryd]

@pheuter The fix was to store more information in the snapshot, so you'd need to create a new migration and manually remove the drop table operations from it, but the next migration should be fine.

[pheuter]

@AndriySvyryd That's what I did:

1. Delete Migrations/ folder and database file (Sqlite)
2. Execute dotnet ef migrations add Base
3. Execute dotnet ef database update
4. Execute dotnet ef migrations add Second

And it was after executing step 4 that I got a migration with the DropTable again.

[AndriySvyryd]

@pheuter Could you open another issue and share a repro? The one in the initial comment here is fixed.

[pheuter]

@AndriySvyryd My mistake, I updated the SDK and dotnet ef cli tools, but forgot to update the project nuget ef core packages. Thanks again for looking into and fixing this issue 🙏