C# .NET Email Regular Expression Validation

Question

Can anyone correct the expression below to also not allow blank field?

<asp:RegularExpressionValidator ID="expEmail" runat="server" ControlToValidate="txtEmail" ErrorMessage="valid email address required" ValidationExpression="^([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]){1,70}$"></asp:RegularExpressionValidator>

Answer 1

Add a required field validator as well - I think the regex validator will only fire if there is text in the field to look at.

Answer 2

RegExp to check email:

^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$

Example [email protected]

Answer 3

If you want to treat this field as required one then it is better go for RequiredFieldValidator.

    <asp:RequiredFieldValidator ID="reqEmail" ControlToValidate="txtEmail" runat="server" ErrorMessage="Email address required"></asp:RequiredFieldValidator>

Thanks,

Answer 4

You need to use an additional validator - asp:RequiredFieldValidator

<asp:RequiredFieldValidator runat="server" ControlToValidate="txtEmail" ErrorMessage="Message!" />

Any of ASP.NET 2.0 validators based on BaseValidator (except RequiredFieldValidator itself of course) doesn't checks specified field to be empty.

Btw, to make custom UserControl being able to be checked with such validators, use [System.Web.UI.ValidationProperty("PropertyName")]

Answer 5

Can't you make something like

if (txtEmail.Text.Trim().length > 0) then
       validate

I think that since regular expressions are rather complex, anything that can be done outside the regular expression should be done outside the regular expression, this should make the code more readable, but that is just me.

Your regular expression is quite complex, here you should find a simpler one. Anyways, what you can do is something like this: ^(regex){1}$

Answer 6

Another choice is to use .net CustomValidator, set its ValidateEmptyText to True, and for email address validation you can use a JavaScript function which will be specified in ClientValidationFunction property of validator.