HasKey changed functionality in 2.1.1 Service Release

[danjohnso]

When overriding calls to HasKey for an entity, the newest servicing release changes behavior and does not override previous calls to HasKey. The first call to HasKey is used to generate a Unique Constraint on the field, which looks to be broken as HasKey is supposed to be for defining a primary key (only one).

Using this example context in a brand new project:

public class Thing : Entity
{
	public Guid ParentId { get; set; }

	public string Name { get; set; }
	public string Code { get; set; }
}

public abstract class Entity
{
	public Guid Id { get; set; }

	public byte[] RowVersion { get; set; }
}

public static class EntityMapping
{
	public static EntityTypeBuilder<T> MapEntity<T>(this EntityTypeBuilder<T> entity, bool isAutoId = true) where T : Entity
	{
		entity.HasKey(x => x.Id);

		if (isAutoId)
		{
			entity.Property(x => x.Id).ValueGeneratedOnAdd().HasDefaultValueSql("NEWID()");
		}
		else
		{
			entity.Property(x => x.Id).ValueGeneratedNever();
		}

		entity.Property(x => x.RowVersion).IsRowVersion();

		return entity;
	}
}

public class TestContext : DbContext
{
	protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
	{
		optionsBuilder
			.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Test;ConnectRetryCount=0");
	}

	protected override void OnModelCreating(ModelBuilder modelBuilder)
	{
		modelBuilder.Entity<Thing>().Map();
	}
}

internal static class ThingEntityExtensions
{
	public static EntityTypeBuilder<Thing> Map(this EntityTypeBuilder<Thing> entity)
	{
		entity.ToTable(nameof(Thing));
		entity.MapEntity(false);
		entity.HasKey(x => new { x.Id, x.ParentId });

		entity.Property(x => x.Name).IsRequired().HasMaxLength(250);

		return entity;
	}
}

The migration generated in 2.1.0 is:

public partial class Init : Migration
{
	protected override void Up(MigrationBuilder migrationBuilder)
	{
		migrationBuilder.CreateTable(
			name: "Thing",
			columns: table => new
			{
				Id = table.Column<Guid>(nullable: false),
				RowVersion = table.Column<byte[]>(rowVersion: true, nullable: true),
				ParentId = table.Column<Guid>(nullable: false),
				Name = table.Column<string>(maxLength: 250, nullable: false),
				Code = table.Column<string>(nullable: true)
			},
			constraints: table =>
			{
				table.PrimaryKey("PK_Thing", x => new { x.Id, x.ParentId });
			});
	}

	protected override void Down(MigrationBuilder migrationBuilder)
	{
		migrationBuilder.DropTable(
			name: "Thing");
	}
}

In 2.1.1, the migration adds a unique constraint like it is applying both calls to HasKey and not overwriting the earlier call like it did before.

public partial class Init : Migration
{
	protected override void Up(MigrationBuilder migrationBuilder)
	{
		migrationBuilder.CreateTable(
			name: "Thing",
			columns: table => new
			{
				Id = table.Column<Guid>(nullable: false),
				RowVersion = table.Column<byte[]>(rowVersion: true, nullable: true),
				ParentId = table.Column<Guid>(nullable: false),
				Name = table.Column<string>(maxLength: 250, nullable: false),
				Code = table.Column<string>(nullable: true)
			},
			constraints: table =>
			{
				table.PrimaryKey("PK_Thing", x => new { x.Id, x.ParentId });
				table.UniqueConstraint("AK_Thing_Id", x => x.Id);
			});
	}

	protected override void Down(MigrationBuilder migrationBuilder)
	{
		migrationBuilder.DropTable(
			name: "Thing");
	}
}

Further technical details

EF Core version: 2.1.1
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10
IDE: Visual Studio 2017 15.7.4

[ajcvickers]

@danjohnso Thanks for reporting this. The fix in 2.1.1 that causes this issue can be reverted by setting the app switch "Microsoft.EntityFrameworkCore.Issue12119" to true as documented here: https://msdn.microsoft.com/en-us/library/system.appcontext.setswitch(v=vs.110).aspx