asp.net mvc - Mvc validation regular expression only numbers?

Question

I tried the following code for digits-only validation for a contact number validation in Mvc web app.

[RegularExpression(@"/(^(d{10})?)$/", ErrorMessage = "Please enter proper contact details.")]
[Required]
[Display(Name = "Contact No")]
public string ContactNo { get; set; }

But the validation expression is not working.

For the contact number I want to only accept digits. It can be either a 10 digit mobile number or a land-line number.

Answer 1

If don't have any restrictions other than numbers only, this should fit:

[RegularExpression(@"^d+$", ErrorMessage = "Please enter proper contact details.")]
[Required]
[Display(Name = "Contact No")]
public string ContactNo { get; set; }