Question

I am trying to subclass the password recovery control in asp.net (4) so that I can override the behaviour of the OnVerifyingUser event but I’m having trouble adding my subclassed password recovery control into the page. I tried creating an asp:placeholder control and adding a new instance of my subclassed control to it but I just get an error that says “An entry with the same key already exists”. I’ve tried doing this in the page_init and page_load methods but get the same error.

Here’s an example of my subclass

Partial Class MyPasswordReminder
    Inherits PasswordRecovery

    Protected Overrides Sub OnVerifyingUser(e As System.Web.UI.WebControls.LoginCancelEventArgs)
        MyBase.OnVerifyingUser(e)
        'Do my stuff here
    End Sub

End Class

And here is how I’m adding it to the page.

 Private Sub Page_Init(sender As Object, e As System.EventArgs) Handles Me.Init
   Dim passwordRecoveryControl As New MyPasswordReminder
   passwordRecoveryControl.ID = "passwordRecoveryControl1"
   Placeholder1.Controls.Add(passwordRecoveryControl)
 End Sub

The UI code is just a simple:

<asp:Panel runat="server" ID="pnlMakeDefault" >
  <asp:Placeholder ID="Placeholder1" runat="server"/>
</asp:Panel>

At runtime I get the following error:

DefaultSource Error: 2 : An entry with
the same key already exists. An entry
with the same key already exists.

Full error:

An entry with the same key already
exists. Description: An unhandled
exception occurred during the
execution of the current web request.
Please review the stack trace for more
information about the error and where
it originated in the code.

Exception Details:
System.ArgumentException: An entry
with the same key already exists.

Source Error:

An unhandled exception was generated
during the execution of the current
web request. Information regarding the
origin and location of the exception
can be identified using the exception
stack trace below.

Stack Trace:

[ArgumentException: An entry with the
same key already exists.]
System.Collections.Specialized.ListDictionary.Add(Object
key, Object value) +7952083
System.Web.UI.ClientScriptManager.RegisterExpandoAttribute(String
controlId, String attributeName,
String attributeValue, Boolean encode)
+337 System.Web.UI.ScriptRegistrationManager.RegisterExpandoAttribute(Control
control, String controlId, String
attributeName, String attributeValue,
Boolean encode) +115

Does anyone know why? I suspect it’s something to do with the validation controls in the base class of the password recovery control but I’m a bit at a loss as to how to proceed.

Answer 1

Not exactly sure why it was an issue but eventually I found that setting the ClientID mode of the control to AutoID solved the problem. My suspicion is that there were validation controls being generated by the control that had conflicting identities but I wasn’t able to prove it.