如何从EF6中的表中读取浮点数据

Question

I try to read data from database

  db.Table1.Load(); 

and get exception

Specified cast is not valid.

StackTrace:

   в System.Data.SQLite.SQLiteDataReader.VerifyType(Int32 i, DbType typ)
   в System.Data.SQLite.SQLiteDataReader.GetDouble(Int32 i)
   в System.Data.Entity.Core.Objects.Internal.ShapedBufferedDataRecord.ReadDoubl
e(DbDataReader reader, Int32 ordinal)
   в System.Data.Entity.Core.Objects.Internal.ShapedBufferedDataRecord.Initializ
e(DbDataReader reader, DbSpatialDataReader spatialDataReader, Type[] columnTypes
, Boolean[] nullableColumns)
   в System.Data.Entity.Core.Objects.Internal.ShapedBufferedDataRecord.Initializ
e(String providerManifestToken, DbProviderServices providerServices, DbDataReade
r reader, Type[] columnTypes, Boolean[] nullableColumns)
   в System.Data.Entity.Core.Objects.Internal.BufferedDataReader.Initialize(Stri
ng providerManifestToken, DbProviderServices providerServices, Type[] columnType
s, Boolean[] nullableColumns)
   в System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[T
ResultType](ObjectContext context, ObjectParameterCollection parameterValues)
   в System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResult
s>b__a()
   в System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`
1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, B
oolean releaseConnectionOnSuccess)
   в System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResult
s>b__9()
   в System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute[TResult]
(Func`1 operation)
   в System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMerg
eOption)
   в System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.I
Enumerable<T>.GetEnumerator>b__0()
   в System.Lazy`1.CreateValue()
   в System.Lazy`1.LazyInitValue()
   в System.Lazy`1.get_Value()
   в System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   в System.Data.Entity.QueryableExtensions.Load(IQueryable source)

other tables are loaded normally.

like

 db.Table2.Load(); // works just fine, all columns has type string

Table1 has columns with the type double but the standard delimiter character in my culture is a comma.

I thought that this should help but does not work either

            System.Threading.Thread.CurrentThread.CurrentCulture =
                System.Globalization.CultureInfo.InvariantCulture;
            System.Threading.Thread.CurrentThread.CurrentUICulture =
                System.Globalization.CultureInfo.InvariantCulture;

I still getting the exception

or am I looking for the error is not where I need it?

Answer 1

I fixed it. I go to github and saw that VerifyType method is independent of current culture:

case TypeAffinity.Double:
          if (typ == DbType.Single) return affinity;
          if (typ == DbType.Double) return affinity;
          if (typ == DbType.Decimal) return affinity;
          if (typ == DbType.DateTime) return affinity;
break;

I checked the type of columns in database (it wasn't created by me) and it was text . I fixed by setting types to numeric .

I hope it help someone too.