The control and the RE’s
Probability the easiest to validate the user input and check if the user entered with a valid e-mail or URL address is using the RegularExpressionValidator. It is control included in ASP .NET 3.5 which you can use to prevent users from submitting the wrong type of data into a database table.
The RegularExpressionValidator enables you to compare a value against a regular expression. You can use a regular expression to represent string patterns such as email addresses, Social Security numbers, phone numbers, dates and product codes.
We have several options to represent e-mails as a regular expression. Above I show some of them:
\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*
This regular expression matches an email address that contains non-whitespace characters, followed by an @ sign, followed by non-whitespace characters, followed by a period, followed by more non-whitespace characters.
^(([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+([;.](([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+)*$
This one will accept multiple e-mails separated only by semi-colons.
\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*([,;]\s*\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*)*
This one validates 1 or more email addresses. The e-mail addresses can be delimited with either comma or semicolon. White space is allowed after delimiter, but not necessary.
^[\w-]+(\.[\w-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)*?\.[a-z]{2,6}|(\d{1,3}\.){3}\d{1,3})(:\d{4})?$
Matches a valid email address including ip’s and or port number after the @. This ER matches address like this: username@domain.com, u-s_e.r1@s-ub2.domain-name.museum:8080 or user_name@123.123.123.12
Below some samples for Regular Expression using to validate domains, URL’s and IP’s.:
^[a-zA-Z0-9\-\.]+\.(com|org|net|mil|edu|COM|ORG|NET|MIL|EDU)$
This regular expression tests the validity of a domain or hostname.
(http|ftp|https):\/\/[\w\-_]+(\.[\w\-_]+)+([\w\-\.,@?^=%&:/~\+#]*[\w\-\@?^=%&/~\+#])?
This one matches any internet URLs.
^(([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+)\.([0-2]*[0-9]+[0-9]+))$
And finally, this one will match simple IP addresses.
The Code
Getting back to the code, now all you need to do is to insert the control and assigned to the RegularExpressionValidator control’s ValidationExpression property with the regular expression you want to use.
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<%@ Page Language=”VB” AutoEventWireup=”false” CodeFile=”Default.aspx.vb” Inherits=”_Default” %>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”> <html xmlns=”http://www.w3.org/1999/xhtml”> <head runat=”server”> <title>Untitled Page</title> </head> <body> <form id=”form1″ runat=”server”> <div>
Enter email address: <asp:TextBox ID=”TextBoxemail” runat=”server” style=”margin-top: 0px” Width=”257px”></asp:TextBox> <br /> <br /> <asp:Button ID=”Buttonsubmit” runat=”server” Text=”Join the Party” /> <br /> <br />
<asp:RegularExpressionValidator ID=”RegularExpressionValidator1″ runat=”server” ControlToValidate=”TextBoxemail” ValidationExpression= “^(([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+([;.](([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5}){1,25})+)*$” ErrorMessage=”Let’s review what an email address looks like”></asp:RegularExpressionValidator>
</div> </form> </body> </html> |
Tip
If you open the property sheet for a RegularExpressionValidator control in Design view and select the ValidationExpression property, you can view a number of canned regular expressions. Visual Web Developer includes regular expressions for patterns such as email addresses, phone numbers, and Social Security numbers.
More information (References)
- ASP .NET 3.5 Unleashed
- http://www.sweeting.org/mark/html/revalid.php
- http://regexlib.com
