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Object Reference Not Set Error with DB2DataReader

HELP!!

I'm getting the error illustrated by the stack trace below, the offending line has an arrow pointing to it, and the calling and component code follows.  I can't understand why I'm getting this error.  The exact same code works fine if I use it on SQLServer with a SqlDataReader.  This is driving me nuts, can someone help?

Line 48:         Dim dr As DB2DataReader = oRepDb.Db2Report(oRep)
Line 49:         dgWebView.DataSource = dr
Line 50:         dgWebView.DataBind() <------ Error Line
Line 51:         If Not dr Is Nothing Then
Line 52:             dr.Close()

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   IBM.Data.DB2.DB2DataReader.Read() +185
   System.Data.Common.DbEnumerator.MoveNext() +44
   System.Web.UI.WebControls.DataGrid.CreateAutoGeneratedColumns(PagedDataSource dataSource) +268
   System.Web.UI.WebControls.DataGrid.CreateColumnSet(PagedDataSource dataSource, Boolean useDataSource) +190
   System.Web.UI.WebControls.DataGrid.CreateControlHierarchy(Boolean useDataSource) +682
   System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) +49
   System.Web.UI.WebControls.BaseDataList.DataBind() +23
   cfss.reports_e.Button1_Click(Object sender, EventArgs e) in c:\inetpub\wwwroot\cfss\home_e.aspx.vb:50
   System.Web.UI.WebControls.Button.OnClick(EventArgs e)
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +18
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
   System.Web.UI.Page.ProcessRequestMain() +1277
   
Calling Code:
   
Private Sub btnDb2WebView_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDb2WebView.Click
    Dim oRep As New CfssReport()
    Dim oRepDb As New CfssReportDB()
    'populate the report object to pass to the db class
    With oRep
        .Name = "scac32"
        .Category = "purch"
        .Format = "web"
        .Source = "db2"
        .Sql = "SELECT DISTINCT T2.DSTRCT_CODE, T2.WHOUSE_ID, FROM BS6TSTW.MSF23101 T2 WHERE T2.WHOUSE_ID = 'MAIN' WITH UR"
    End With
    Dim dr As DB2DataReader = oRepDb.Db2Report(oRep)
    dgWebView.DataSource = dr
    dgWebView.DataBind()
    dr.Close()
End Sub

Component Code:

Public Class CfssReportDB

    Public Function Db2Report(ByVal oCfssReport As CfssReport) As DB2DataReader

        ' Create Instance of Connection and Command Objects
        Dim oConn As DB2Connection = New DB2Connection(ConfigurationSettings.AppSettings("db2ConnString"))
        Dim oComm As DB2Command = New DB2Command(oCfssReport.Sql, oConn)
        Try
            If oConn.State = ConnectionState.Closed Then
                oConn.Open()
            End If
            Dim dr As DB2DataReader = oComm.ExecuteReader(CommandBehavior.CloseConnection)

            ' Return the datareader result
            Return dr

        Catch e As DB2Exception

            If oConn.State = ConnectionState.Open Then
                oConn.Close()
            End If
            oConn.Dispose()
           
        Finally
       
            oComm.Dispose()
        End Try

    End Function
   
End Class
0
brunka
Asked:
brunka
1 Solution
 
Bob LearnedCommented:
Sounds like a bug with the DB2DataReader to me.

Bob
0
 
wguerramCommented:
Bob,

It is possible to bind a DataReader to a DataGrid?
0
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DotNetLover_BaanCommented:
try using dataset. lets see where is the real error ..
-Baan
0
 
brunkaAuthor Commented:
Looks like it could very well be a bug with the DB2DataReader.  Using the exact same code, I switched to an OleDbDataReader and the function returns the reader just fine.

To respond to Baan's comment I also tried a dataset only making necessary modifications to the code to use a DB2Connection and return a dataset, the function returned the dataset just fine as well.

I'm going to get a hold of IBM, and see what they say.

Next question then, what's the ideal solution in the meantime for data retreival, using a fast OleDbDataReader with it's comparitively slow OLEDB provider or a slower dataset using the faster DB2.NET provider knowing the app can often return 1000's of records at a time?

Thanks,

Adam
0
 
Bob LearnedCommented:
What kind of operations are you looking to do with the data?  If you are doing a one-time read operation, then a DataReader would be better.  But if you are looking for Updates, Insert, and Deletes, then a DataSet would be the better option.

Bob
0
 
brunkaAuthor Commented:
It's for one-time reads.

Adam
0
 
Bob LearnedCommented:
Then I would go with the DataReader.

Bob
0

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