Я использую EF Core 1.1.0, и у меня есть серьезная проблема с каскадным поведением.
У меня есть модель под названием Land, как показано ниже:
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; }
}
и еще одна модель под названием Building:
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; }
}
и в dbcontext я упомянул такое отношение:
...
modelBuilder.Entity<Land>()
.HasOne(l => l.Building)
.WithMany(b => b.Lands)
.HasForeignKey(l => l.BuildingId)
.OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.SetNull);
...
но когда я пытаюсь обновить базу данных, я получаю эту ошибку:
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.
сгенерированная миграция выглядит примерно так:
...
migrationBuilder.AddForeignKey(
name: "FK_Lands_Buildings_BuildingId",
table: "Lands",
column: "BuildingId",
principalTable: "Buildings",
principalColumn: "Id",
onDelete: ReferentialAction.SetNull);
...
Я сказал, что установил для внешнего ключа значение null при удалении, но он не хочет, чтобы я предпринимал какие-либо действия. Хотя в dbcontext нет поведения под названием «NoAction»!