Validate User Information on Registration Page

Question

I want to create a registration page for my web site.

I have three Text Boxes, one for user name, another for password and third for repeat password.

<asp:TextBox ID="UserName" runat="server"></asp:TextBox>  
<asp:TextBox ID="PassWord" runat="server"></asp:TextBox>  
<asp:TextBox ID="RE-Pass" runat="server"></asp:TextBox>

Now I want to check these three Text Box's values.

For the first Text Box, I should check it's value by connecting to a database to check it's unique. For the two other text boxes, I should check their values are the same.

I used on blur event but it is a client side (javascript) event not a server side event.

How can I check these value using on blur event or any other way?

Answer 1

Just use ASP.net validator controls.

For the password textboxes, use the CompareValidator control.

From MSDN:

Compares the value entered by the user in an input control with the value entered in another input control, or with a constant value.

You'd need something along the lines of:

<asp:textbox ID="Textbox1" runat="server" TextMode="Password"></asp:textbox>
<asp:textbox ID="Textbox2" runat="server" TextMode="Password"></asp:textbox>
<asp:CompareValidator ID="CompareValidator1" runat="server" ErrorMessage="No Match." ControlToValidate="Textbox1" ControlToCompare="Textbox2"></asp:CompareValidator>

For the username textbox you could use a Custom Validator control.

You'll need something along the lines of:

ASPX Page

<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="Invalid User     Name" ControlToValidate="TextBox3" 
OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator>

Code Behind

protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
{
     bool userNameIsValid = true; // Database check here.

     if (userNameIsValid)
         args.IsValid = true
     else  
         args.IsValid = false;
   }

Here's a tutorial on MSDN which describes using this control to validate user input against a database.