Highlight text in .NET, .Select() isn't available

Question

I have a Web Forms textbox in a gridview and I want to higlight the text on a button click. textbox.select(start,end) doesn't work. Here is the code:

    Dim row As GridViewRow = TryCast(DirectCast(sender, ImageButton).Parent.Parent, GridViewRow)
    Dim txtdays As TextBox = row.Cells(2).FindControl("txtDays")
    Dim lbldays As Label = row.Cells(2).FindControl("lblDays")
    Dim btndel As ImageButton = row.Cells(2).FindControl("btndel")
    Dim imgbttnadd As ImageButton = row.Cells(2).FindControl("imgbttnadd")

    //Show textbox and set its text.
    txtdays.Visible = True
    txtdays.Text = lbldays.Text
    txtdays.Focus()

    //Here is where I want to select the text.
    txtdays.Select() //????????  Doesn't work.

How do you do this?

.Select works on Windows Forms textboxes but not Web Forms textboxes.

Answer 1

Based on your comments, you might want to specify in your question that you're dealing with an ASP.NET control. The answer Chris gave does work on a WinForms textbox.

I'm not sure how you'd do it in ASP.NET, but I can bet you can't do it in server-side code. You'll probably have to use JavaScript to pull it off.

Answer 2

You need to understand that a client side script will be needed to execute the effect you desire. However, server-side code would be required to accurately identify the element. This is why you need the "rendered ID" of the txtDays TextBox (since it lies in a GridView, the rendered ID will be different)

Using JavaScript, you can do it as follows:

The following code would be in your ASPX page, for instance (you may want to wrap it in a function). I'm assuming that you have basic familiarity with JavaScript.

var txtDays = document.getElementById(<%= txtDays.ClientID %>);
if (txtDays != null)
{
    txtDays.focus();
    txtDays.select();
}

The Select function you are looking for in VB does not exist. The Focus() function only exists (.NET 2.0+) because of the implementation of the Focus API, which renders a JavaScript function similar to the above sample in client side code.

Edit: (after comments)

In that case, I guess you can use something like the following instead of the line that does not work (in your code sample).

txtDays.Attributes.Add("onfocus", "this.select();")

This should ensure that when the onfocus event is raised, the TextBox will be selected as well.