Does anyone know what the regex used by the email validator in ASP.NET is?
Here is the regex for the Internet Email Address using the RegularExpressionValidator in .NET
\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*
By the way if you put a RegularExpressionValidator on the page and go to the design view there is a ValidationExpression field that you can use to choose from a list of expressions provided by .NET. Once you choose the expression you want there is a Validation expression: textbox that holds the regex used for the validator
I don't validate email address format anymore (Ok I check to make sure there is an at sign and a period after that). The reason for this is what says the correctly formatted address is even their email? You should be sending them an email and asking them to click a link or verify a code. This is the only real way to validate an email address is valid and that a person is actually able to recieve email.
E-mail addresses are very difficult to verify correctly with a mere regex. Here is a pretty scary regex that supposedly implements RFC822, chapter 6, the specification of valid e-mail addresses.
Not really an answer, but maybe related to what you're trying to accomplish.
We can use RegularExpressionValidator to validate email address format. You need to specify the regular expression in ValidationExpression property of RegularExpressionValidator. So it will look like
<asp:RegularExpressionValidator ID="validateEmail"
runat="server" ErrorMessage="Invalid email."
ControlToValidate="txtEmail"
ValidationExpression="^([\w\.\-]+)#([\w\-]+)((\.(\w){2,3})+)$" />
Also in event handler of button or link you need to check !Page.IsValid.
Check sample code here : sample code
Also if you don't want to use RegularExpressionValidator you can write simple validate method and in that method usinf RegEx class of System.Text.RegularExpressions namespace.
Check example:
example
For regex, I first look at this web site: RegExLib.com
Apart from the client side validation with a Validator, I also recommend doing server side validation as well.
bool isValidEmail(string input)
{
try
{
var email = new System.Net.Mail.MailAddress(input);
return true;
}
catch
{
return false;
}
}
Related
I am using the asp.net validation control to validate email addresses. There was an issue with an email address because it has the following characters. "-." For example the email address w.-a.wsdf.com will not validate due to the ".-" in it. I was looking around for email standards that forbid this but could not find any. Should I change the asp.net regex to a custom one to allow this or is this not a valid email address?
The regex i am using now is : \w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*
You'll get loads of answers for this. This one has always served me well:
/\A[\w+\-.]+#[a-z\d\-.]+\.[a-z]+\z/i
Originally found it in Michael Hartl's Rails book
^[a-zA-Z][\w\.-]*[a-zA-Z0-9]#[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$
Regular expressions are great but, as my comments showed in other answers, validating email addresses with them is not an easy task at all.
Based on my experience, I would suggest to either:
stick to the simplest email validation regex, ^.+#.+$ and send a confirmation email with an activation link;
or
avoid using regular expressions at all and use a library like my EmailVerify for .NET, which exposes a custom, fine tuned finite state machine for validating email addresses according to (all of) the related IETF standards plus disposable, DNS, SMTP, mailbox tests.
Obviously you can mix the two alternatives and perhaps avoid using regular expressions but send a confirmation link anyway.
Disclaimer: I am the tech lead of EmailVerify for .NET, a Microsoft .NET component for validating email addresses.
The regex below forbids w.-a.wsdf.com
using System.Text.RegularExpressions;
public static bool IsValidEmail(string email)
{
return Regex.IsMatch(email, #"\A[a-z0-9]+([-._][a-z0-9]+)*#([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,4}\z")
&& Regex.IsMatch(email, #"^(?=.{1,64}#.{4,64}$)(?=.{6,100}$).*");
}
See validate email address using regular expression in C#.
Take a text input in html and a button input like this
Now when the button is clicked then the JavaScript function SubmitFunction() will be called. Now write the bellow code in this function.
function checkEmail() {
var email = document.getElementById('txtEmail');
var filter = /^([a-zA-Z0-9_\.\-])+\#(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (!filter.test(email.value)) {
alert('Please provide a valid email address');
email.focus;
return false;
}
}
*its works *
I'm developing a module where I need to take input from a user one of each is users email. In order to filter out a wrong input I want to check if a corresponding checkbox has an # sign.
Does anyone knows how can I check it using vb.net ?
Aside the main question to check if a string contains the # character and considering that you are getting your string from a user input, in your case I think is better to check if the user entered a valid mail address.
To do so there are some solutions all reported in this other SO question How do I validate email address formatting with the .NET Framework?
In ASP.NET you can use RegularExpressionValidator for this.
<asp:RegularExpressionValidator ID="regexEmailValid" runat="server"
ValidationExpression="\w+([-+.]\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*"
ControlToValidate="tbEmail"
ErrorMessage="Invalid Email Format">
</asp:RegularExpressionValidator>
I am building a form and i want to prevent certain characters from being typed in a textbox?
I want to disable the " and ' characters in some of my textboxes
You can use a RegularExpressionValidator along with a regex such as [^"'] to allow all characters except " and '.
(please note, that regex is untested at the moment...)
ASP.NET Validators have both client and server APIs for validation.
The safest way is to check the form values on the server-side to see if the input is valid (doesn't include quote characters in your case) and respond with an error if it is invalid.
On the client side, I've had good luck using jQuery Validation.
Remember that arbitrary form payloads can be constructed outside of a browser, so you always have to check data validity on the server, even if client-side validation is in place.
Using an AJAX ASP FilterTextBox Control would be the way I'd go.
<ajaxToolkit:FilteredTextBoxExtender ID="ftbe" runat="server"
TargetControlID="TARGETCONTROLIDHERE"
FilterType="Custom, Numbers, LowerCaseLetters, UpperCaseLetters, Symbols"
InvalidChars="&" />
You can simply remove those characters from the string before you perform your database operation.
I need to set validation on a textbox where the user types in their email address... This is not a required field though so I want to allow the form to be submitted if the textbox contains the default text ("Email address").
I've posted the code i have already to ensure a valid email address is typed.
<asp:RegularExpressionValidator CssClass="errorpopup" Display="Dynamic" ID="regexpEmail"
ValidationGroup="mySubmit" runat="server" ErrorMessage="<strong>Please enter a valid email address.</strong>"
ControlToValidate="tbEmail" ValidationExpression="\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*"
SetFocusOnError="true" />
Just enclose the entire regex in (?:...)? to make it optional.
But you're not using a very good e-mail validation regex. Aside from the fact that e-mail addresses can never reliably be validated by regular expressions, you could do a little better by using
^(?:[\w.%+-]+#(?:[\w-]+\.)+[A-Za-z]{2,6}\s*|Email address)?$
This will still not catch all valid addresses, and will match some invalid addresses. But short of the RFC 2822 implementation regex which spans about four or five lines of code, this is probably a good compromise.
I have two textbox called BIRTH & EMAIL, and I must test in button click if the user has typed a date & email format in those two TextBox.
How can do that ?
Take a look at DateTime.TryParse for the date.
For the e-mail, unfortunately using regular expressions is probably your best bet.
Use a RegularExpressionValidator for each field, in conjunction with a RequiredFieldValidator. There are some ready made regular expressions for both that can be accessed through the properties window of the control.
The ValidationExpression is where you set the regular expression.
Why dont you use the ASP .NET Validators?
http://support.microsoft.com/kb/316662
Seems like the RegularExpressionValidator along with the RequiredFieldValidator would be perfect for this.
Note: The Regular Expression Validator already has the email option in the pre populated list.
For the date field, I would use the date picker, or some other control that let the user enter the day, month, and year separately. That way you don't have to worry about ambiguous dates, such as 01/05/2010, or even worse 01/05/10 (is that y/m/d, d/m/y, m/d/y etc.), and other such problems. For email address, I would do a simple check for the "#" symbol, and a dot, but don't get any more stringent than that. Email addresses can be pretty weird. You can also make them type the email address twice to ensure that they typed it correctly.
As you're using VB.NET, I believe IsDate(dateValue) is a simple option to validate the date.
Regular Expressions are your best bet though.
There's a fairly long discussion on SO regarding email regexes here:
Using a regular expression to validate an email address