Why won't my ASP.NET CustomValidator validate?

Question

I must be doing something wrong. I can't seem to execute my CustomValidator's ServerValidate method.

I've got a Visual Basic ASP.NET page with a CustomValidator...

<asp:TextBox ID="TextBox1" runat="server" />
<asp:CustomValidator ID="CustomValidator1" runat="server"
    ControlToValidate="TextBox1"
    ErrorMessage="Friendly message goes here."
    Display="Dynamic" />
<asp:Button ID="Button1" runat="server"
    Text="Submit"
    CausesValidation="True" />

For this test, I've got the validation set to always fail...

Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles CustomValidator1.ServerValidate
    args.IsValid = False
End Sub

But, when the button is clicked, the CustomValidator1_ServerValidate() method never executes!

Protected Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Page.Validate()
    If Page.IsValid Then
        'it executes the code here!
    End If
End Sub

Not even if I explicitly validate that control...

CustomValidator1.Validate() 'does nothing?

What am I doing wrong?

Answer 1

I know it's a daft question (or might sound like it!) But have you actually entered/changed the value in the Textbox? I think the validator won't trigger without the contents of the textbox changing

Answer 2

Add the property:

 ValidateEmptyText="True"

Answer 3

Are you putting the validator control submit button in the same validation group?

Answer 4

Firstly, You seem to be missing the OnServerValidate attribute in your markup above.

Secondly, I would check to ensure that CustomValidator1_ServerValidate has been set up as an eventhandler for the ServerValidate event for Textbox1. I have had occasions where I have changed the name of the validate method in the markup and code-behind, but the IDE has not auto updated the subscribing method name passed to the eventhandler delegate