Chapter 9 ErrorMessage / Button Click

ChuckASP · March 10th, 2010, 11:08 AM

After completing the first "Try it out" on page 296, I wanted to try something different. I added some code in the code behind file Controls/ContactForm.ascx.vb for the button_click sub for the Send button. The code is supposed to display the ErrorMessage from the RequiredFieldValidator1 control in a label that I added, if the text box for the name is empty. To debug the code, I put a breakpoint on the button_click sub for the Send button, but it only steps through the code when I put and name in the box and click Send. It will not step throught the sub if the text box is empty and I click send. I'm I forgetting something from a previous lesson?
Here's my code:

Code:

 
Partial Class Controls_ContactForm
    Inherits System.Web.UI.UserControl

  Protected Sub btnSend_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSend.Click

    If txtName.Text = String.Empty Then
      lblForMessage.Text = RequiredFieldValidator1.ErrorMessage.ToString
    End If


  End Sub
End Class

Imar · March 10th, 2010, 11:16 AM

Isn't RequiredFieldValidator1 preventing you from submitting to the server in the first place?

What exactly are you trying to accomplish? Can you post the relevant pieces of code from the markup and Code Behind?

Imar

ChuckASP · March 10th, 2010, 12:01 PM

Tell me if this is true: The button_click sub is not executed if the validation fails (Last 2 sentences under "How it works", page 296.) That is why it doesn't step into the routine. In other words, if validation fails the button_click sub is not executed even though you click the button. ASP doesn't waste time executing the sub and submitting to the server if validation fails at the client. Is this correct?
What I was trying to do is write some code to display both the error Text "*" in one cell and the ErrorMessage in a seperate label that I put in another cell in the table. Just trying experiment a little.

Thanks,

Chuck

Imar · March 10th, 2010, 12:24 PM

Quote:

ASP doesn't waste time executing the sub and submitting to the server if validation fails at the client. Is this correct?

Yes, but in reversed order.

ASP.NET validation is split in two parts: client side and server side. When client side validation fails the page does not submit to the server and ASP.NET never comes into play. So, it doesn't execute the Sub as the request never makes it to the server.

Once you turn client side validation off, the page does submit to the server where your code will run. Just to clarify once more: client side validation should only be used as a courtesy to the user. You shouldn't rely on it for true validation purposes; you must use server side validation for this.

Cheers,

Imar