In a comment on another post about validating parameters for the SqlDataSource control, someone asks about how to handle errors that might occur within the SqlDataSource control -- e.g. "query timeout, SQL Server not running, mistake in query," to quote the comment. I thought it was worthwhile to promote the discussion from the comments to a separate entry. (If you read those comments, there's nothing new here for you ...)
Eilon confirmed that the data source controls don't raise their own error events. You can trap errors like the ones listed, but you have to do so slightly indirectly.
You have (at least) two choices. One is to perform data binding yourself and put the DataBind call into a try-catch block:
Sub Page_Load()You can also catch the error in the Page_Error handler (documented here). Handle the Page_Error event and then redirect (using Server.Transfer) to an error page. Here's the handler:
If Not IsPostBack Then
GridView1.DataSourceID = "SqlDataSource1"
Catch ex As Exception
' Hopefully better error handling that this ...
Response.Write("Error data binding")
Sub Page_Error()And a possibility for the target page:
Sub Page_Load()This will catch all unhandled errors in the page, which I guess is a good thing or a bad thing, depending.
Label1.Text = Server.GetLastError.Message
PS You can also create an application-level error handler. (#)