Recreate deleted database using Entity Framework

Question

I'm trying to develop a Windows Form Application using Entity Framework CodeFirst. It worked fine until I deleted the database. Tried to rebuild it, but I get this message error. No change has been made to the classes from whom the database is to be created. I have taken out the classes for database build and the code spippet (using context from below) and I've put them in another project, no problems encountered. Still, in my application project I get this:

************** Exception Text **************
System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Invalid column name 'Text'.
Invalid column name 'NumberOfCorrectAnswers'.
   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)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
   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.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
   --- End of inner exception stack trace ---
   at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
   at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass3.<GetResults>b__2()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass3.<GetResults>b__1()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
   at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at BD___TestingPlatform.AL.AL_Load(Object sender, EventArgs e) in d:\Cursuri\VS Projects\BD\Examen\BD - TestingPlatform\BD - TestingPlatform\AL.cs:line 98
   at System.Windows.Forms.Form.OnLoad(EventArgs e)
   at System.Windows.Forms.Form.OnCreateControl()
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl()
   at System.Windows.Forms.Control.WmShowWindow(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.ContainerControl.WndProc(Message& m)
   at System.Windows.Forms.Form.WmShowWindow(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

I have to mention I deleted the migrations folder, tried to solve the problem from Package Console Manager, nothing worked. I made sure that the initial database is deleted, by looking in the directory where they are created. I also deleted the database and migrations from another sample app, and there are no problems when recreated.

Because the database is created only if you do an operation on it(for example, select), I have this snippet with whom I'm trying to trigger the process.

using (TestingPlatformContext ctx = new TestingPlatformContext())
                {
                    //MessageBox.Show("Database created successfully");

                    var query = (from q in ctx.Questions    //line 98
                                 select q).ToList();
                    //{ QuestionID=q.QuestionID, Text=q.Text }).ToList();

                    if (query.Count == 0)
                        MessageBox.Show("No results");
                }

My question class is the following:

public class Question
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int QuestionID { get; set; }

        public string Text { get; set; }
        public int NumberOfAnswers { get; set; }
        public int NumberOfCorrectAnswers { get; set; }

        public int PersonID { get; set; }
        public int SubjectID { get; set; }
        public virtual List<Answer> Answers { get; set; }
    }

P.S.: I'm using Visual Studio 2012, EntityFramework 6.1.1.

anIBMer · Accepted Answer · 2014-08-09 12:13:49Z

1

clean the solution, and check your database connection string in web.config. And check whether you have deleted the correct database.

On another note, By calling a property name "Text", i believe if this will cause you problem or at least confusions down the track. Names like Description is more likely a better choice.

answered Aug 9, 2014 at 12:13

anIBMer

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1 Comment

Tanatos Daniel Over a year ago

Indeed, I haven't deleted the right database. The database it connected was one to which I had not applied some migrations, thus it did not have columns 'Text' and 'NumberOfCorrectAnswers'. The App.config file did not contain any specific connection string, so I couldn't check it that way. But I added a verification for database existance, else create it and it showed me the database. Next I deleted with the migrations and after compiling, everything worked fine. Should've been more careful.

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