C'è già un oggetto chiamato nel database
database ef-code-first ef-migrations entity-framework entity-framework-6
Domanda
Aggiornamento del database non riuscito dalla console di Gestione pacchetti. Ho usato Entity Framework 6.x e approccio code-first. L'errore è
"C'è già un oggetto chiamato 'AboutUs' nel database."
Come posso risolvere questo problema?
internal sealed class Configuration
: DbMigrationsConfiguration<Jahan.Blog.Web.Mvc.Models.JahanBlogDbContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = true;
AutomaticMigrationDataLossAllowed = false;
}
protected override void Seed(Jahan.Blog.Web.Mvc.Models.JahanBlogDbContext context)
{
}
}
Il mio DbContext è:
public class JahanBlogDbContext : IdentityDbContext<User, Role, int, UserLogin, UserRole, UserClaim>
{
public JahanBlogDbContext()
: base("name=JahanBlogDbConnectionString")
{
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<JahanBlogDbContext>());
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Comment>().HasRequired(t => t.Article).WithMany(t => t.Comments).HasForeignKey(d => d.ArticleId).WillCascadeOnDelete(true);
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<User>().ToTable("User");
modelBuilder.Entity<Role>().ToTable("Role");
modelBuilder.Entity<UserRole>().ToTable("UserRole");
modelBuilder.Entity<UserLogin>().ToTable("UserLogin");
modelBuilder.Entity<UserClaim>().ToTable("UserClaim");
}
public virtual DbSet<Article> Articles { get; set; }
public virtual DbSet<ArticleLike> ArticleLikes { get; set; }
public virtual DbSet<ArticleTag> ArticleTags { get; set; }
public virtual DbSet<AttachmentFile> AttachmentFiles { get; set; }
public virtual DbSet<Comment> Comments { get; set; }
public virtual DbSet<CommentLike> CommentLikes { get; set; }
public virtual DbSet<CommentReply> CommentReplies { get; set; }
public virtual DbSet<ContactUs> ContactUs { get; set; }
public virtual DbSet<Project> Projects { get; set; }
public virtual DbSet<ProjectState> ProjectStates { get; set; }
public virtual DbSet<ProjectTag> ProjectTags { get; set; }
public virtual DbSet<Rating> Ratings { get; set; }
public virtual DbSet<Tag> Tags { get; set; }
public virtual DbSet<AboutUs> AboutUs { get; set; }
}
Console di gestione dei pacchetti:
PM> update-database -verbose -force
Using StartUp project 'Jahan.Blog.Web.Mvc'.
Using NuGet project 'Jahan.Blog.Web.Mvc'.
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Target database is: 'Jahan-Blog' (DataSource: (local), Provider: System.Data.SqlClient, Origin: Configuration).
No pending explicit migrations.
Applying automatic migration: 201410101740197_AutomaticMigration.
CREATE TABLE [dbo].[AboutUs] (
[Id] [int] NOT NULL IDENTITY,
[Description] [nvarchar](max),
[IsActive] [bit] NOT NULL,
[CreatedDate] [datetime],
[ModifiedDate] [datetime],
CONSTRAINT [PK_dbo.AboutUs] PRIMARY KEY ([Id])
)
System.Data.SqlClient.SqlException (0x80131904): There is already an object named 'AboutUs' 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, Boolean asyncWrite)
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.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 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, DbInterceptionContext interceptionContext)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ExecuteSql(DbTransaction transaction, MigrationStatement migrationStatement, DbInterceptionContext interceptionContext)
at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbTransaction transaction, DbInterceptionContext interceptionContext)
at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbConnection connection)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClass30.<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, DbTransaction existingTransaction)
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.AutoMigrate(String migrationId, VersionedModel sourceModel, VersionedModel targetModel, Boolean downgrading)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.AutoMigrate(String migrationId, VersionedModel sourceModel, VersionedModel targetModel, Boolean downgrading)
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:88b66414-8776-45cd-a211-e81b2711c94b
There is already an object named 'AboutUs' in the database.
PM>
Risposta accettata
sembra che ci sia un problema nel processo di migrazione, eseguire il comando add-migration in "Package Manager Console":
Add-Migration Initial -IgnoreChanges
apportare alcune modifiche e quindi aggiornare il database dal file "Iniziale":
Update-Database -verbose
Modifica: -IgnoreChanges è in EF6 ma non in EF Core, ecco una soluzione: https://stackoverflow.com/a/43687656/495455
Risposta popolare
Forse hai cambiato lo spazio dei nomi nel tuo progetto!
C'è una tabella nel tuo database chiamata dbo.__MigrationHistory . La tabella ha una colonna chiamata ContextKey .
Il valore di questa colonna è basato sul tuo namespace . per esempio è " DataAccess.Migrations.Configuration ".
Quando si modifica lo spazio dei nomi, vengono generati nomi di tabelle duplicati con spazi dei nomi diversi.
Quindi, dopo aver cambiato spazio dei nomi nel codice, cambia anche lo spazio dei nomi in questa tabella nel database (per tutte le righe).
Ad esempio, se si modifica lo spazio dei nomi in EFDataAccess , è necessario modificare i valori della colonna ContextKey in dbo.__MigrationHistory in " EFDataAccess.Migrations.Configuration ".
Quindi, nel lato del codice, in Strumenti => Console Gestione pacchetti, utilizzare il comando update-database .
Un'altra opzione invece di modificare il valore di contesto nel database consiste nel codificare in modo rigido il valore di contesto nel codice con il valore del vecchio spazio dei nomi. Ciò è possibile ereditando DbMigrationsConfiguration<YourDbContext> e nel costruttore basta assegnare il vecchio valore di contesto a ContextKey , che ereditare da MigrateDatabaseToLatestVersion<YourDbContext, YourDbMigrationConfiguration> e lasciare la classe vuota. L'ultima cosa da fare è chiamare Database.SetInitializer(new YourDbInitializer()); nel tuo DbContext in un costruttore statico.
Spero che il problema verrà risolto.
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