ASP.Net: Ajax registration question

Question

I worked with: ASP.Net: Ajax check for registration as a user?

It has a few errors, I don't understand:

1) It worked only one time for one textbox. If the textbox is edited a second time, the breakpoint will not be hited. Why?

2) For my Email, I have a check, that there is no duplicate, when there is one, there should the set an error panel visible, but it don't show.

        protected void txtEMail_TextChanged(object sender, EventArgs e)
    {
        Business.UserHandling uh = new Business.UserHandling();
        if (uh.CheckIfEmailExists(txtEMail.Text))
        {
            panelHelp.Visible = true;
            lblHelp.Text = "EMail existriert schon.";
        }
    }

Answer 1

When the update mode is conditional

<asp:scriptmanager runat="server" id="sm1" />
<asp:updatepanel runat="server" id="up1" updatemode="Conditional"> // here the updatemode is conditional ...
<contenttemplate>
    <asp:textbox runat="server" id="tbUsername" autopostback="true" ontextchanged="tbUsername_TextChanged" />
    <asp:customvalidator runat="server" text="Email already used" id="cusValEmail" />
    <asp:textbox runat="server" id="tbPassword"  />
</contenttemplate>
</asp:updatepanel>

You need to call

protected void txtEMail_TextChanged(object sender, EventArgs e)
{
    Business.UserHandling uh = new Business.UserHandling();
    if (uh.CheckIfEmailExists(txtEMail.Text))
    {
        panelHelp.Visible = true;
        lblHelp.Text = "EMail existriert schon.";
    }
    up1.Update(); // call to update the update panel "up1"
}

Sorry I'm a bit rusty, it's a while since I've used update panels.

Answer 2

After an update panel updates you must reinitialise the javascript on the html elements inside it.

So, to the end of your method you could add:

protected void txtEMail_TextChanged(object sender, EventArgs e)
{
    Business.UserHandling uh = new Business.UserHandling();
    if (uh.CheckIfEmailExists(txtEMail.Text))
    {
        panelHelp.Visible = true;
        lblHelp.Text = "EMail existriert schon.";
    }
    // Re-init javascript
    ScriptManager.RegisterStartupScript(Type, String, "add onchange js here", Boolean);
}

see http://msdn.microsoft.com/en-us/library/system.web.ui.clientscriptmanager.registerstartupscript.aspx