Invalid Cast Exception when trying to set DataGrid DataSource = IDataReader object (why??...)

Posted on 2007-11-21
Medium Priority
Last Modified: 2011-09-20
Here is my code which calls a function that returns an IDataRreader object (I have verified that the IDataReader is populated with the correct data set I wish to use as my DataSource):

      dgMyGrid.DataSource = GetIDataReaderDataSource()

            dgBillTo.DataBind()   'fails on this line with "Invalid Cast Exception"
        Catch ex As Exception
        End Try

Can someone tell me why this is occuring and what I can do alternatively to make it work?

Thanks much in advance.
Question by:OddiC
  • 2
LVL 25

Expert Comment

ID: 20332222
have you defined all your grid columns are non-nullable types, i.e. "int" instead of "int?"
if you have, then any nulls in the data will cause that error
LVL 27

Accepted Solution

Sammy earned 1500 total points
ID: 20332952
I would check if the method returns a datareader first before you set it as the datasource
Dim DataReader as DataReader=GetIDataReaderDataSource()
If (Not (DataReader) Is Nothing) Then
'Bind here
End If
Try this as an alternative "does NOT in 1.1, only 2.0 and after"

Dim oDataTable As DataTable = New DataTable
dgMyGrid.DataSource = oDataTable

Author Comment

ID: 20350220
I am working with 1.1

I am not sure how I define the grid column types as they are not being auto-generated and are defined at runtime based on the datasource.

Any thoughts?

Author Comment

ID: 20350885
I figured it out. I needed to use DataTable instead of DataReader (my cast on ItemDataBound was not working with DataReader).

This is what was failing because the datasource was datareader:

 Dim odr As DataRowView = DirectCast(e.Item.DataItem, DataRowView)

Does anyone know how the above can be accomplished with a DataSource of DataReader?? (just for piece of mind).


Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Today is the age of broadband.  More and more people are going this route determined to experience the web and it’s multitude of services as quickly and painlessly as possible. Coupled with the move to broadband, people are experiencing the web via …
The article shows the basic steps of integrating an HTML theme template into an ASP.NET MVC project
The video provides a quick and easy steps to migrate MBOX file to well known Outlook PST and Office 365. Besides this, it also supports and migrates more than 20 email clients of MBOX which include AppleMail, Opera, Thunderbird and SeaMonkey effortl…
Watch the video of Kernel Migrator for SharePoint, which demonstrate the process easily of migration from SharePoint to SharePoint, OneDrive for Business & Google Drive servers, Public Folder to SharePoint, File Server to SharePoint. The tool has va…

624 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question