Show ErrorMessage in an own model property - regex

Question

I've created my own model property, which says "ErrorMessage could not be found":
[DataType(DataType.EmailAddress)]
[Required]
[Display(Name = "Email")]
[StringLength(80, ErrorMessage = "Email too large.")]
[RegularExpressionTimeOut(#"^([a-zA-Z0-9._-]+)#(outlook|hotmail|yahoo)\.\w{2,}$", 5),
ErrorMessage = "Invalid email."] // 5 seconds
public string Email { get; set; }
And the class of this property:
public class RegularExpressionTimeOut :
System.ComponentModel.DataAnnotations.ValidationAttribute
{
public System.TimeSpan TimeOut { get; set; }
public string Pattern { get; set; }
//public string ErrorMessage { get; set; }
//new System.TimeSpan(0, 0, 5)
/// <summary>
/// Constructor
/// </summary>
/// <param name="pattern">Regular expression as string</param>
/// <param name="timeOut">Number of seconds</param>
public RegularExpressionTimeOut(string pattern, int timeOut)
{
this.Pattern = pattern;
this.TimeOut = new System.TimeSpan(0, 0, timeOut);
}
public override bool IsValid(object value)
{
//if (!string.IsNullOrEmpty(this.ErrorMessage) && ...)
return (new System.Text.RegularExpressions.Regex(this.Pattern,
System.Text.RegularExpressions.RegexOptions.None, this.TimeOut))
.IsMatch(this.Pattern);
}
}
Then, the question is, how can I show the ErrorMessage?
Updated with the FormatErrorMessage
My web don't show the error message anyway.
public class RegularExpressionTimeOut : System.ComponentModel.DataAnnotations.ValidationAttribute
{
public System.TimeSpan TimeOut { get; set; }
public string Pattern { get; set; }
private const string DefaultErrorMessage = "Invalid email.";
//private string ErrorMessage;
/// <summary>
/// Constructor
/// </summary>
/// <param name="pattern">Regular expression as string</param>
/// <param name="timeOut">Number of seconds</param>
public RegularExpressionTimeOut(string pattern, int timeOut) : base(DefaultErrorMessage)
{
this.Pattern = pattern;
this.TimeOut = new System.TimeSpan(0, 0, timeOut);
//this.ErrorMessage = errorMessage;
}
public override bool IsValid(object value)
{
//if (!string.IsNullOrEmpty(this.ErrorMessage) && ...)
return (new System.Text.RegularExpressions.Regex(this.Pattern, System.Text.RegularExpressions.RegexOptions.None, this.TimeOut)).IsMatch(this.Pattern);
}
public override string FormatErrorMessage(string ErrorMessage)
{
return string.Format(ErrorMessageString, ErrorMessage);
}
}

Answer 1

You RegularExpressionTimeOut constructor does not have a parameter for ErrorMessage. The typical usage is
public class RegularExpressionTimeOut : ValidationAttribute
{
private const string DefaultErrorMessage = "Invalid email";
public RegularExpressionTimeOut(string pattern, int timeOut) : base(DefaultErrorMessage)
and usually an override is added to format a specific message provide in the Attribute where you access values such as the property name (although in your case you don't seem to be needing or wanting that.
public override string FormatErrorMessage(string name)
{
return string.Format(ErrorMessageString, name, .....);
}
Side note: your closing parenthesis is not located correctly. It should be
[RegularExpressionTimeOut(#"....", 5, ErrorMessage = "Invalid email.")]
Edit
Your not actually testing the value of the Email property which is posted back (you just testing that the regex pattern matches itself. You need to change the IsValid() method to
public override bool IsValid(object value)
{
string email = (string)value; // cast it to a string for use in the Regex method
return (new Regex(this.Pattern, RegexOptions.None, this.TimeOut)).IsMatch(email);
}
Note also that the regex pattern you have shown should take a few millisecond to test so its not clear why you would need this. In addition, you do not have any associated client side validation (your attribute does not implement ICientValitable and in any case there would be no point since javascript regex does not have a timeout) so the message would only be returned if you return the view when ModelState.IsValid == false. In that case, your message "Invalid email" would be rather confusing to the user and it should probably indicate that it needs to be #outlook or #hotmail etc.