Impossibile aggiornare il database utilizzando Migrazioni EF dopo l'aggiornamento a EF 6.0.0-alpha

Question

Dopo aver aggiornato il mio Entity Framework alla versione 6.0.0-alpha1 non posso aggiornare il database. Questo è l'errore che sto ricevendo:

PM> update-database -verbose 
Using StartUp project 'DataCenter'. 
Using NuGet project 'DataCenter.Domain'. 
Specify the '-Verbose' flag to view the SQL statements being applied to the target database. 
Target database is: 'datacenter' (DataSource: ., Provider: System.Data.SqlClient, Origin: Configuration). 
Upgrading history table. 
ALTER TABLE [dbo].[__MigrationHistory] ADD [ContextKey] [nvarchar](512) NOT NULL DEFAULT 'DataCenter.Domain.Migrations.Configuration' 
ALTER TABLE [dbo].[__MigrationHistory] DROP CONSTRAINT [PK_dbo.__MigrationHistory] 
System.Data.SqlClient.SqlException (0x80131904): 'PK_dbo.__MigrationHistory' is not a constraint. 
Could not drop constraint. See previous errors. 
    at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) 
    at System.Data.SqlClient.SqlInternalConnection.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) 
    at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite) 
    at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() 
    at System.Data.Entity.Migrations.DbMigrator.ExecuteSql(DbTransaction transaction, MigrationStatement migrationStatement) 
    at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ExecuteSql(DbTransaction transaction, MigrationStatement migrationStatement) 
    at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`1 migrationStatements) 
    at System.Data.Entity.Migrations.Infrastructure.MigratorBase.ExecuteStatements(IEnumerable`1 migrationStatements) 
    at System.Data.Entity.Migrations.DbMigrator.UpgradeHistory(IEnumerable`1 upgradeOperations) 
    at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.UpgradeHistory(IEnumerable`1 upgradeOperations) 
    at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration) 
    at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration) 
    at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.RunCore() 
    at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run() 
ClientConnectionId:eda1a366-d3c8-44de-8cc9-8f64e2511b4e 
'PK_dbo.__MigrationHistory' is not a constraint. 
Could not drop constraint. See previous errors. 

Qual è la causa di questo? Ho interrogato la tabella sysobjects per "PK_dbo .__ MigrationHistory" ma questo non esiste. qualche idea?

Grazie in anticipo.

Answer 1

OK. Ho trovato la soluzione. Sembra che EF si aspetti che il vincolo della chiave primaria della tabella __MigrationHistory abbia il nome PK_dbo.__MigrationHistory. ma è PK___MigrationHistory.

Quindi le seguenti istruzioni sql faranno il trucco.

ALTER TABLE __MigrationHistory 
drop CONSTRAINT PK___MigrationHistory 
ALTER TABLE __MigrationHistory 
ADD CONSTRAINT [PK_dbo.__MigrationHistory] PRIMARY KEY (MigrationId) 

dopo questo ho usato update-database senza errori.