Hiding Formview If No Results

gothael · February 7th, 2008, 01:30 PM

Hello. I've got a FormView that outputs several variables into a paragraph. Is there any way to hide this control (and the entire paragraph that is inside it) if the data source that the control is using returns no results (or maybe certain results)? I was thinking maybe I should use the data binding function of the control, but I couldn't find out how to refer to any of the result set fields from the data binding function. Thank you! :)

Imar · February 9th, 2008, 08:23 AM

Hi there,

Doesn't the FormView hide itself when there's no data?

I just did a quick test and when I have no items in the data source, I don't see the FormView's contents appear, even though I had set up a <HeaderTemplate>

That said, you can do what you want by handling the events of the data source control. How to do this depends on the data source. With a SqlDataSource control you can handle the Selected event and test the AffectedRows property of the e argument:

Code:

protected void SqlDataSource1_Selected(object sender, SqlDataSourceStatusEventArgs e)
{
  FormView1.Visible = e.AffectedRows > 0;
}

Hope this helps,

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
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gothael · February 11th, 2008, 10:18 AM

Now that I think about it, it does not display when there are no results. I have some records though, that have empty strings in their fields. When that is the case, how can I make the control invisible? It seems that maybe the datasource doesn't treat empty strings as nulls? Thanks for your help.

Imar · February 11th, 2008, 01:58 PM

Null is indeed not the same as an empty string. However, my guess is that even with null values they would still show up, because there is still a row. Whether or not your row consists of null values doesn't matter, a row is a row.

Depending on your data structure, you can filter them out at the database level. Alternatively, hook into events like RowDataBound of your data-aware control and filter out the relevant rows there.

Without knowing more of your setup / code, it's difficult to recommend something more accurate.

Hope this helps,

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.