Page.IsValid changes to false after button click

[Andrew Jocelyn]

Hi

I have couple of dropdown controls each with a requiredfieldvalidator. I
clear the dropdownlist in the button click event. When the page is rendered
the dropdown validator already flags it's error message. I checked the
IsValid property in the prerender event and it says it's false.

protected void Button_Click(object sender, EventArgs e)
{
ddl.ClearSelection();
Trace.Write(Page.Validators[0].IsValid.ToString()); // returns True
}

protected override void OnPreRender(EventArgs e)
{
Trace.Write(Page.Validators[0].IsValid.ToString()); // returns False
base.OnPreRender(e);
}

What could be happening to change the IsValid property to false? I can't see
anything in my code which would do this. What's the best way to debug this?
What other checks should I be making?

Many thanks
Andrew

 

[bruce barker]

Page.IsValid runs the validation logic. so if you clear a selection, then use
Page.IsValid to run a validation check, it will fail.

-- bruce (sqlwork.com)

 

[Andrew Jocelyn]

Hi Bruce

That doesn't seem to be the case in my simple test with a single validator
on a page. The Page.IsValid value does not change how ever many times I call
it. However it does change in my project page which contains a FormView
control with a number of UserControls. What I don't seem to be able to do is
find out where or why it's changing.

Any ideas?

Thanks
Andrew

 

[Steven Cheng [MSFT]]

Hi Andrew,

According to your description, I've performed some tests, it seems a simple
page with dropdownlist and requiredFieldValidator will not produce the
exact behavior. Here is a simple test page I used:

========aspx============
<form id="form1" runat="server">
<div>

</div>
<aspropDownList ID="DropDownList1" runat="server">
<asp:ListItem></asp:ListItem>
<asp:ListItem>aaa</asp:ListItem>
<asp:ListItem>bbb</asp:ListItem>
<asp:ListItem>ccc</asp:ListItem>
</aspropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
ControlToValidate="DropDownList1"
ErrorMessage="RequiredFieldValidator"></asp:RequiredFieldValidator>
<br />
<br />
<aspropDownList ID="DropDownList2" runat="server">
<asp:ListItem></asp:ListItem>
<asp:ListItem>aaa</asp:ListItem>
<asp:ListItem>bbb</asp:ListItem>
<asp:ListItem>ccc</asp:ListItem>
</aspropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server"
ControlToValidate="DropDownList2"
ErrorMessage="RequiredFieldValidator"></asp:RequiredFieldValidator>
<br />
<br />
<aspropDownList ID="DropDownList3" runat="server">
<asp:ListItem></asp:ListItem>
<asp:ListItem>aaa</asp:ListItem>
<asp:ListItem>bbb</asp:ListItem>
<asp:ListItem>ccc</asp:ListItem>
</aspropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server"
ControlToValidate="DropDownList3"
ErrorMessage="RequiredFieldValidator"></asp:RequiredFieldValidator>
<br />
<br />
<asp:Button ID="btnPost" runat="server" onclick="btnPost_Click"
Text="Post Button" />
<asp:Button ID="btnClear" runat="server" onclick="btnClear_Click"
Text="Clear Button" />
</form>


=-========code behind=======
public partial class ValidatePage : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void btnPost_Click(object sender, EventArgs e)
{

}
protected void btnClear_Click(object sender, EventArgs e)
{
Response.Write("<br/>Page.IsValid: " + Page.Validators[0].IsValid);

DropDownList1.ClearSelection();
DropDownList2.ClearSelection();
DropDownList3.ClearSelection();

Response.Write("<br/>Page.IsValid: " + Page.Validators[0].IsValid);
}

protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);

Response.Write("<br/>Page.IsValid: " + Page.Validators[0].IsValid);
}
}
=======================

It seems as long as the page postback(when I click the Clear Button) and
passed client-side validation, the server-side validation won't return
false after I "ClearSelection" on the dropdownlists.

As you mentioned that there are other forms and usercontrols, I'm wondering
whether some input entry in them may cause the problem. Have you tried
removing some of them to isolate the behavior?

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


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