CODEWITHSUNDEEP
c#asp.net.netregexvalidation
LiamB
LiamB

Reputation: 18586

Email Regular Expression Validation

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>

Upvotes: 8

Views: 55232

Answers (8)

akrisanov
akrisanov

Reputation: 3214

One of the solutions (not a best one) is to implement some regular expression:

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

Sample: [email protected]

But actually, it's very hard to write and maintain a good email validation regexp. You shouldn't trust 100% your regex. You can find several articles about that difficulty on the Internet:

Upvotes: 18

Avinash
Avinash

Reputation: 1277

This can be done with simply using Regex class in System.Text.RegularExpressions:

private bool ValidateEmail()
{
    string email = txtemail.Text;
    Regex regex = new Regex(@"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$");
    Match match = regex.Match(email);
    if (match.Success)
       return true;
    else
       return false;
}

Upvotes: 0

Muhammad Mubashir
Muhammad Mubashir

Reputation: 1659

void Page_Load(Object sender, EventArgs e)
{
    string uNameExpr = "^[a-zA-Z](.{1,9})$";
    string phoneExpr = 
        "((\\(\\d{3}\\) ?)|(\\d{3}-))?\\d{3}-\\d{4}";

    // Define validation expressions.
    RegExprVal1.ValidationExpression = uNameExpr;
    RegExprVal2.ValidationExpression = phoneExpr;

    ReqFldVal1.Text = "User name is required";
    RegExprVal1.Text = "Must be between 2 to 10 characters";
    RegExprVal2.Text = "Please provide a valid number: (425) 555-0187";
    // ErrorMessages appear in ValidationSummary.
    RegExprVal1.ErrorMessage = "Incorrect UserName format. Name" +
        " can be 2 to 10 characters long";
    ReqFldVal1.ErrorMessage = "User name required";
    RegExprVal2.ErrorMessage = 
        "Please provide a valid number: (000) 000-0000";
}

void OnCmdClick(Object sender, EventArgs e)
{
    if (Page.IsValid)
    {
        ActiveForm = Form2;
    }
}

Upvotes: 0

abatishchev
abatishchev

Reputation: 100238

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")]

Upvotes: 1

MUS
MUS

Reputation: 1450

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.

Upvotes: 0

npinti
npinti

Reputation: 52185

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}$

Upvotes: 1

Bimal
Bimal

Reputation: 1243

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,

Upvotes: 0

Paddy
Paddy

Reputation: 33857

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.

Upvotes: 11

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