EF6 抛出指定的强制转换对异步方法无效

如何解决EF6 抛出指定的强制转换对异步方法无效

当使用 await 和 FirstOrDefaultAsync 时，我得到指定的强制转换无效异常。

var a = Db.Table1.sqlQuery("select * from Table1 where rownum =1 ").FirstOrDefault();
var b = await Db.Table1.sqlQuery("select * from Table1 where rownum =1 ").FirstOrDefaultAsync();

所以 a 很好 b 抛出错误。我错过了什么？

   at System.Data.Common.DbDataReader.GetFieldValue[T](Int32 ordinal)
   at System.Data.Common.DbDataReader.GetFieldValueAsync[T](Int32 ordinal,CancellationToken cancellationToken)
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Core.Objects.Internal.ShapedBufferedDataRecord.<ReadIntAsync>d__25.MoveNext()
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Utilities.TaskExtensions.CultureAwaiter.GetResult()
   at System.Data.Entity.Core.Objects.Internal.ShapedBufferedDataRecord.<InitializeAsync>d__4.MoveNext()
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Core.Objects.Internal.BufferedDataReader.<InitializeAsync>d__0.MoveNext()
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Core.Objects.ObjectContext.<ExecuteStoreQueryInternalAsync>d__73`1.MoveNext()
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Utilities.TaskExtensions.CultureAwaiter`1.GetResult()
   at System.Data.Entity.Core.Objects.ObjectContext.<ExecuteInTransactionAsync>d__3d`1.MoveNext()
   at System.Runtime.ExceptionServices.ExceptiondispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Data.Entity.Utilities.TaskExtensions.CultureAwaiter`1.GetResult()
   at System.Data.Entity.Infrastructure.DbExecutionStrategy.<ProtectedExecuteAsync>d__9`1.MoveNext()

解决方法

如果有人遇到这个问题，我会发布一个答案。 Table1 EF 模型中缺少某些属性，或者换句话说，表 Table1 有额外的字段。为什么这不会导致 FirstOrDefault 并且只导致 FirstOrDefaultAsync 错误我不知道，可能是不同的实现。所以解决办法是同步Table1 DB表和Table1 EF模型