Specified cast is not valid

[Andy Sutorius via DotNetMonster.com]

Hi,

I am attempting to set the CssClass programatically of an asp.net table
row. My html is below. My code behind with the error on line 313 is also
below. I attempted to cast the data from the data reader into a table row
and then set the table row's CssClass but got the error. How can I set the
CssClass of the <tr> programmitcally?

Thanks!

Andy

<tr id="hp_loc_016_da01" runat="server">
<td>Patient Signature Source A</td>
<td><asp:textbox id="txtPatientSignatureSourceA"
Runat="server"></asp:textbox></td>
</tr>


Line 311: while (dtrElecDemoData.Read())
Line 312: {
Line 313: TableRow troHiliteRowID = (TableRow) dtrElecDemoData["hilite"];
Line 314: troHiliteRowID.CssClass = "highlightrowyellow";
Line 315: }


Source File: c:\inetpub\wwwroot\ecui_1\wpclaimhcfaelecdemodata.aspx.cs
Line: 313

 

[Kevin Spencer]

A DataTable has a DataRows Collection of TableRows. A DataReader, having
only one record in it at a time, does not.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
What You Seek Is What You Get.

 

[Andy Sutorius via DotNetMonster.com]

I should clarify...it is not an asp.net table it's an html table with one
of the rows marked with and id and a runat attribute.

 

[Mike via DotNetMonster.com]

You cannot use runat="server" for TR. It is not an ASP.NET control.

 

[Kevin Spencer]

You're still trying to cast a DataReader as whatever it is that you say
you're using.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
What You Seek Is What You Get.

 

[Andy Sutorius via DotNetMonster.com]

Well your comment intrigues me. Using intellisense I was able to see that
the HTMLTableRow has a bgcolor property but not cssclass property. I have
hard-coded the rows bgcolor. How can I do this dynamically?

while (dtrHighlightError.Read())
{
// TableRow troHiliteRowID = (TableRow) dtrHighlightError["hilite"];
// troHiliteRowID.CssClass = "highlightrowyellow";

hp_loc_016_da01.BgColor = "#ffff99";

}

 

[Mike via DotNetMonster.com]

You cannot access TR from code behind. id="hp_loc_016_da01" will be visible
only for the client script. ASP.NET does not create an object for it. You
can use something like this:

ASP.NET:
<tr class="<%= GetTRClass() %>">
....
</tr>

Code behind:
protected string GetTRClass()
{
return "highlightrowyellow";
}

As an alternative you can use DataGrid or another similar Web control. In
that case you will be able to access TR as an object, but the code will
require more resources.

 

[Mike via DotNetMonster.com]

Sorry. I forgot that ASP.NET can convert table tags to objects if you add
runat=server. However you need to add a protected field for your TR to the
code behind class.

ASP.NET:
<tr id="myTr" runat="server">
....
</tr>


Code behind:
protected HtmlTableRow myTr;

private void Page_Load(object sender, System.EventArgs e)
{
myTr.BgColor = "#ffff99";
}

 

[Andy Sutorius via DotNetMonster.com]

Mike,

Thanks for your help. I have the protected in place. 1 more step! How to
get the .bgcolor to be associated with dtrHighlightError["hilite"]