Unable to cast object of type 'Microsoft.Practices.EnterpriseLibrary.Data.RefCountingDataReader' to type 'System.Data.SqlClient.SqlDataReader'.

Question

User310329504 posted

I have this function:

    Public Function AssignedDepartmentDetail(ByVal Did As Integer) As SqlDataReader
        Dim reader As SqlDataReader
        Dim Command As SqlCommand = db.GetSqlStringCommand("select seomthing from somewhere where something = @did")
        db.AddInParameter(Command, "@did", Data.DbType.Int32, Did)
        reader = db.ExecuteReader(Command)
        reader.Read()
        Return reader
    End Function

This gives the following error on db.ExecuteReader line:

Unable to cast object of type 'Microsoft.Practices.EnterpriseLibrary.Data.RefCountingDataReader' to type 'System.Data.SqlClient.SqlDataReader'.

How do I go about getting this working? Will I always run into problems when dealing with the reader?

Answer 1

User-25924017 posted

Try using 

Dim reader as IDataReader reader = db.ExecuteReader(command); 'and then cast it to SqlDataReader

or

Dim reader as RefCountingDataReader  = (RefCountingDataReader) db.ExecuteReader(command);

if (((SqlDataReader)reader.InnerReader).HasRows) //Its C#, please convert

{

}

Answer 2

User310329504 posted

I think the later code sample converts to:

Public Function ExecuteReader(ByVal db As Database) As SqlDataReader
        Dim reader As RefCountingDataReader = DirectCast(db.ExecuteReader(), RefCountingDataReader)
        Return DirectCast(reader.InnerReader, SqlDataReader)
    End Function

You then get an error:

DirectCast(db.ExecuteReader(), RefCountingDataReader)

Overload resolution failed because no accessible 'ExecuteReader' accepts this number of arguements.

Answer 3

User-25924017 posted

Public Function ExecuteReader(ByVal db As Database, ByVal command as SqlCommand) As SqlDataReader
        Dim reader As RefCountingDataReader = DirectCast(db.ExecuteReader(command), RefCountingDataReader)
        Return DirectCast(reader.InnerReader, SqlDataReader)
    End Function

It needs command parameter. My VB is not good, so adjust.

Answer 4

User693495898 posted

Dear Sir :

Thanks for your sharing.

I've meeted the same problem and I found out another article to solve it.

For your refernce --  http://entlib.codeplex.com/Thread/View.aspx?ThreadId=211288

This is my Blog for recording this problem.

http://www.dotblogs.com.tw/mis2000lab/archive/2010/12/17/refcountingdatareader_20101217.aspx

My sample code is  ----------------------------------------------------------------------------------

Imports Microsoft.Practices.EnterpriseLibrary.Data   '-- using EntLib 5.0
Imports System.Data

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim db As Database = DatabaseFactory.CreateDatabase("Your_ConnectionString")

        Dim sqlstr As String = "Select top 10 id,title From test"
        Using I_dr As RefCountingDataReader = CType(db.ExecuteReader(CommandType.Text, sqlstr), RefCountingDataReader)

            GridView1.DataSource = DirectCast(I_dr.InnerReader, System.Data.SqlClient.SqlDataReader)
            GridView1.DataBind()

            '--Thanks these friends help to solve this problem：http://forums.asp.net/p/1560116/3850542.aspx
            '-- http://entlib.codeplex.com/Thread/View.aspx?ThreadId=211288
        End Using

    End Sub