Clear Textbox with Regular Expression Validator - asp.net

Question

I Got a text box with a Regular Expression validator, to validate if my textbox is numeric.
here's the code :
<asp:TextBox ID="txtAmount" runat="server" CssClass="TextBoxCls"></asp:TextBox>
<asp:RegularExpressionValidator runat="server" ID="valNumbersOnly" ControlToValidate="txtAmount"
SetFocusOnError="true" Display="Dynamic" ErrorMessage="Please enter a numbers only in text box."
Font-Bold="true" ForeColor="Red" ValidationExpression="(^([0-9 ]*|\d*\d{1}?\d*)$)">
</asp:RegularExpressionValidator>
and , if the user accidentally input the wrong data , it'll show the Error Like This :
and i give the user, a clear function to clear all the textbox : with kind of this function :
Public Sub ClearTextBox(ByVal root As Control)
For Each ctrl As Control In root.Controls
ClearTextBox(ctrl)
If TypeOf ctrl Is TextBox Then
CType(ctrl, TextBox).Text = String.Empty
End If
Next ctrl
End Sub
Protected Sub btnClr_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnClr.Click
ClearTextBox(Me)
dropResponse.SelectedIndex = 0
FillData()
End Sub
but , the amount is not cleared, it still show the error. why it still happen?

Answer 1

If you are providing this through another button on the same form it won't ever hit the code-behind.
If you want a button on a validated form that needs to fire regardless of whether the other controls have validated, put it in a separate validation group:
<asp:Button runat="server" ID="btnClr" Text="Clear form" OnClick="btnClr_Click" ValidationGroup="unvalidatedControls" />
Alternatively, put a validation group on your controls that need validating and also the button that submits the form:
<asp:TextBox ID="txtAmount" runat="server" CssClass="TextBoxCls" ValidationGroup="validatedControls"></asp:TextBox>
<asp:RegularExpressionValidator runat="server" ID="valNumbersOnly" ControlToValidate="txtAmount"
SetFocusOnError="true" Display="Dynamic" ErrorMessage="Please enter a numbers only in text box."
Font-Bold="true" ForeColor="Red" ValidationExpression="(^([0-9 ]*|\d*\d{1}?\d*)$)"
ValidationGroup="validatedControls">
</asp:RegularExpressionValidator>
<asp:Button runat="server" ID="btnSubmit" Text="Submit Form" ValidationGroup="validatedControls" />
You could put a ValidationGroup attribute on both your clear button and the main form, as long as they're different, the clear button will work just fine.
Some documentation on Validation Groups: http://msdn.microsoft.com/en-us/library/ms227424.aspx

Answer 2

I suspect that the textbox is contained in a panel or another container control. Only the toplevel controls of a page are available in the controls collection of the page.
I would suggest to change the parameter of the call to ClearTextBox with the correct container control.