EF Core DeleteBehavior.SetNull causes cyclic problems

Question

I am using EF Core 1.1.0 and I have a serious problem with cascading behavior.

I have a model called Land like bellow:

public class Land
{
    public long Id { get; set; }
    public int HorizontalPosition { get; set; }
    public int VerticalPosition { get; set; }
    public bool IsPlaced { get; set; }

    // Relations
    public string UserId { get; set; }
    public virtual User User { get; set; }
    public long? BuildingId { get; set; }
    public virtual Building Building { get; set; }
}

and another model called "Construction":

public class Building
{
    public long Id { get; set; }
    public bool IsPermanent { get; set; }
    public int UpgradeCount { get; set; }

    // Relations
    public string UserId { get; set; }
    public virtual User User { get; set; }
    public int BuildingTypeId { get; set; }
    public virtual BuildingType BuildingType { get; set; }
    public virtual List<Land> Lands { get; set; }
}

and in dbcontext I mentioned a relation like this:

...
modelBuilder.Entity<Land>()
            .HasOne(l => l.Building)
            .WithMany(b => b.Lands)
            .HasForeignKey(l => l.BuildingId)
            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.SetNull);
...

but when I try to update the database, I get this error:

System.Data.SqlClient.SqlException: Introducing FOREIGN KEY constraint 'FK_Lands_Buildings_BuildingId' on table 'Lands' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint or index. See previous errors.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite, String methodName)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, String executeMethod, IReadOnlyDictionary`2 parameterValues, Boolean closeConnection)
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_1.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
ClientConnectionId:65b8e08e-2d17-46ac-b734-385f88dd07b1
Error Number:1785,State:0,Class:16
Introducing FOREIGN KEY constraint 'FK_Lands_Buildings_BuildingId' on table 'Lands' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint or index. See previous errors.

the generated migration looks something like this:

...
migrationBuilder.AddForeignKey(
            name: "FK_Lands_Buildings_BuildingId",
            table: "Lands",
            column: "BuildingId",
            principalTable: "Buildings",
            principalColumn: "Id",
            onDelete: ReferentialAction.SetNull);
...

I said that set the foreign key to null for deletion, but he wants me to not do anything. Although there is no behavior in dbcontext called "NoAction"!

Thanks in advance.

TG.

Answer 1

, , SQL Server.

EF Core NO ACTION.

- Restrict ( ).

(, Lands) (User). , , / . catch , .