Consider the following model:
```
public class Foo
{
public int Id { get; set; }
public Bar Bar { get; set; }
}
public class Bar
{
public int Id { get; set; }
public Foo Foo { get; set; }
}
public class MyContext : DbContext
{
public DbSet<Foo> Foos { get; set; }
public DbSet<Bar> Bars { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Foo>().ToTable("Foobar");
modelBuilder.Entity<Bar>().ToTable("Foobar");
modelBuilder.Entity<Foo>().HasRequired(f => f.Bar).WithRequiredPrincipal(b => b.Foo);
}
}
```
Install EF5 or EF6Beta1
Enable-Migrations
Add-Migration Mig1
Update-Database
now, update package with the current nightly build of EF
upon running the application EF will complain that model has changed and new migration should be added.
Add-Migration Mig2
the following migration gets generated:
```
public override void Up()
{
CreateTable(
"dbo.Foobar",
c => new
{
Id = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.Id);
DropTable("dbo.Foobar");
}
public override void Down()
{
CreateTable(
"dbo.Foobar",
c => new
{
Id = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.Id);
DropTable("dbo.Foobar");
}
This migration is invalid, because it tries to create an already existing database, Upon Update-Database command we get the following exception:
System.Data.SqlClient.SqlException (0x80131904): There is already an object named 'Foobar' in the database.
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.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TInterceptionContext,TResult](Func`1 operation, TInterceptionContext interceptionContext, Action`1 executing, Action`1 executed)
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
at System.Data.Entity.Internal.InterceptableDbCommand.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.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbConnection connection)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClass32.<ExecuteStatements>b__2e()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
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.ExecuteOperations(String migrationId, XDocument targetModel, IEnumerable`1 operations, IEnumerable`1 systemOperations, Boolean downgrading, Boolean auto)
at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
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.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
ClientConnectionId:d5286d53-2114-4454-8008-8a9cc9b6ac22
```
```
public class Foo
{
public int Id { get; set; }
public Bar Bar { get; set; }
}
public class Bar
{
public int Id { get; set; }
public Foo Foo { get; set; }
}
public class MyContext : DbContext
{
public DbSet<Foo> Foos { get; set; }
public DbSet<Bar> Bars { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Foo>().ToTable("Foobar");
modelBuilder.Entity<Bar>().ToTable("Foobar");
modelBuilder.Entity<Foo>().HasRequired(f => f.Bar).WithRequiredPrincipal(b => b.Foo);
}
}
```
Install EF5 or EF6Beta1
Enable-Migrations
Add-Migration Mig1
Update-Database
now, update package with the current nightly build of EF
upon running the application EF will complain that model has changed and new migration should be added.
Add-Migration Mig2
the following migration gets generated:
```
public override void Up()
{
CreateTable(
"dbo.Foobar",
c => new
{
Id = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.Id);
DropTable("dbo.Foobar");
}
public override void Down()
{
CreateTable(
"dbo.Foobar",
c => new
{
Id = c.Int(nullable: false, identity: true),
})
.PrimaryKey(t => t.Id);
DropTable("dbo.Foobar");
}
This migration is invalid, because it tries to create an already existing database, Upon Update-Database command we get the following exception:
System.Data.SqlClient.SqlException (0x80131904): There is already an object named 'Foobar' in the database.
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.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TInterceptionContext,TResult](Func`1 operation, TInterceptionContext interceptionContext, Action`1 executing, Action`1 executed)
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
at System.Data.Entity.Internal.InterceptableDbCommand.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.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbConnection connection)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClass32.<ExecuteStatements>b__2e()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
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.ExecuteOperations(String migrationId, XDocument targetModel, IEnumerable`1 operations, IEnumerable`1 systemOperations, Boolean downgrading, Boolean auto)
at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
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.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
ClientConnectionId:d5286d53-2114-4454-8008-8a9cc9b6ac22
```