ASP .NET Problem z Seedem

0

Witajcie, zaopatrzyłem się w książkę pt. "C# 6.0 i MVC 5. Tworzenie nowoczesnych portali internetowych". Tworzę sobie na podstawie przykładowej apki tam zawartej podobną aplikację i jadąc równo z tą książką napotkałem błąd, którego nie mam pomysłu jak się pozbyć. Generalnie pisałem kod metody Seed w konfiguracji migracji. Błąd, jaki zgłasza konsola to: "Object reference not set to an instance of an object.", czepia się funkcji SeedTrainings, poniżej kod całego Seed'a (inne funkcje mam zrobione w zasadzie w podobny sposób i nie zgłaszają żadnych błędów).

internal sealed class Configuration : DbMigrationsConfiguration<Repository.Models.AkademiaWebContext>
    {
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }

        protected override void Seed(AkademiaWebContext context)
        {
            //if(System.Diagnostics.Debugger.IsAttached==false)
            //System.Diagnostics.Debugger.Launch();

            SeedRoles(context);
            SeedUsers(context);
            SeedTrainings(context);
            SeedCategories(context);
            SeedTrainingCategory(context);
        }

        private void SeedRoles(AkademiaWebContext context)
        {
            var roleManager = new RoleManager<Microsoft.AspNet.Identity.EntityFramework.IdentityRole>(new RoleStore<IdentityRole>());
            if (!roleManager.RoleExists("Admin"))
            {
                var role = new Microsoft.AspNet.Identity.EntityFramework.IdentityRole();
                role.Name = "Admin";
                roleManager.Create(role);
            }
        }

        private void SeedUsers(AkademiaWebContext context)
        {
            var store = new UserStore<User>(context);
            var manager = new UserManager<User>(store);
            if (!context.Users.Any(u=>u.UserName == "Admin"))
            {
                var user = new User { UserName = "Admin" };
                var adminresult = manager.Create(user, "1234");

                if (adminresult.Succeeded) manager.AddToRole(user.Id, "Admin");
            }
        }

        private void SeedTrainings(AkademiaWebContext context)
        {
            var idUzytkownika = context.Set<User>().Where(u => u.UserName == "Admin").FirstOrDefault().Id;
            for (int i = 1; i <= 10; i++)
            {
                var train = new Training()
                {
                    Id = i,
                    Content = "Treść kursu " + i.ToString(),
                    Title = "Tytuł kursu " + i.ToString(),
                    AddDate = DateTime.Now.AddDays(-i),
                    UserId = idUzytkownika
                };
                context.Set<Training>().AddOrUpdate(train);
            }
            context.SaveChanges();
        }

        private void SeedCategories(AkademiaWebContext context)
        {
            for (int i=1; i<=10; i++)
            {
                var cat = new Category()
                {
                    Id = i,
                    CategoryName = "Nazwa kategorii " + i.ToString(),
                    ParentId = i
                };
                context.Set<Category>().AddOrUpdate(cat);
            }
            context.SaveChanges();
        }

        private void SeedTrainingCategory(AkademiaWebContext context)
        {
            for (int i = 1; i < 10; i++)
            {
                var TrainCat = new TrainingCategory()
                {
                    Id = i,
                    TrainingId = i / 2 + 1,
                    CategoryId = i / 2 + 2
                };
                context.Set<TrainingCategory>().AddOrUpdate(TrainCat);
            }
            context.SaveChanges();
        }
    }

Wrzucę jeszcze model Training, może tu ktoś coś wypatrzy, chociaż model wydaje mi się okej (zresztą funkcja też, gdybym wiedział jak naprawić ten błąd to nie zawracałbym Wam tyłka)

 public class Training
    {
        public Training()
        {
            this.TrainingCategory = new HashSet<TrainingCategory>();
        }
        [Display(Name = "Id: ")]
        public int Id { get; set; }

        [Display(Name = "Tytuł szkolenia: ")]
        [MaxLength(100)]
        public string Title { get; set; }

        [Display(Name = "Treść lekcji: ")]
        [MaxLength(100000)]
        public string Content { get; set; }

        [Display(Name = "Data dodania: ")]
        [DataType(DataType.Date)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        public System.DateTime AddDate { get; set; }

        public string UserId { get; set; }

        public virtual ICollection<TrainingCategory> TrainingCategory { get; set; }
        public virtual User User { get; set; }
    }

Z góry dzięki za pomoc

1

Obstawiam, że problem jest tutaj

var idUzytkownika = context.Set<User>().Where(u => u.UserName == "Admin").FirstOrDefault().Id;

Prawdopodobnie nie znajdujesz usera, więc .Id wyrzuca Ci wyjątek, bo bierzesz z nulla.

Może dodanie

context.SaveChanges();

Po dodaniu admina w SeedUsers pomoże, lub generalnie sprawdź czy on się w ogóle i dodaje :P

0

Po dodaniu SaveChanges rzeczywiście ten błąd zniknął, jednak teraz na konsoli zawitało "An error occurred while updating the entries. See the inner exception for details." z "krótkim" uzasadnieniem:

Running Seed method.
System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_dbo.TrainingCategory_dbo.Training_TrainingId". The conflict occurred in database "aspnet-AkademiaWeb-20180528074939", table "dbo.Training", column 'Id'.
The statement has been terminated.
   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.SqlDataReader.TryConsumeMetaData()
   at System.Data.SqlClient.SqlDataReader.get_MetaData()
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString, Boolean isInternal, Boolean forDescribeParameterEncryption, Boolean shouldCacheForAlwaysEncrypted)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, Boolean inRetry, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
   at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
   at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c(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.Reader(DbCommand command, DbCommandInterceptionContext interceptionContext)
   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)
   at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.Execute(Dictionary`2 identifierValues, List`1 generatedValues)
   at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
   --- End of inner exception stack trace ---
   at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update[T](T noChangesResult, Func`2 updateFunction)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
   at System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__35()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass2a.<SaveChangesInternal>b__27()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
   --- End of inner exception stack trace ---
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
   at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
   at System.Data.Entity.DbContext.SaveChanges()
   at Repository.Migrations.Configuration.SeedTrainingCategory(AkademiaWebContext context) in C:\Users\kmmar\OneDrive\Dokumenty\Visual Studio 2017\Projects\Praca\AkademiaWeb\Repository\Migrations\Configuration.cs:line 101
   at Repository.Migrations.Configuration.Seed(AkademiaWebContext context) in C:\Users\kmmar\OneDrive\Dokumenty\Visual Studio 2017\Projects\Praca\AkademiaWeb\Repository\Migrations\Configuration.cs:line 28
   at System.Data.Entity.Migrations.DbMigrationsConfiguration`1.OnSeed(DbContext context)
   at System.Data.Entity.Migrations.DbMigrator.SeedDatabase()
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.SeedDatabase()
   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__DisplayClasse.<Update>b__d()
   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.RunCore()
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()

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