asp.net mvc dataannotation validating url

Question

can some one tell me how can i validate a url like http://www.abc.com

Answer 1

Uri.IsWellFormedUriString checks that the URL format is correct and does not require escaping.

/// <summary>
/// Ensures the property is a valid URL.
/// </summary>
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
public class ValidateUrlAttribute :  ValidationAttribute
{
    public ValidateUrlAttribute()
    {
    }

    public override bool IsValid(object value)
    {
        // Do not validate missing URLs - people can use [Required] for that.
        string text = (value as string) ?? "";

        if (text == "")
            return true;

        return Uri.IsWellFormedUriString(text, UriKind.Absolute);
    }
}

Answer 2

Let the System.Uri do the heavy lifting for you, instead of a RegEx:

public class UrlAttribute : ValidationAttribute
{
    public UrlAttribute()
    {
    }

    public override bool IsValid(object value)
    {
        var text = value as string;
        Uri uri;

        return (!string.IsNullOrWhiteSpace(text) && Uri.TryCreate(text, UriKind.Absolute, out uri ));
    }
}

Answer 3

I use this regular expression for Internal or external URLS on my site.

((?:https?\:\/\/|\/.)(?:[-a-z0-9]+\.)*[-a-z0-9]+.*)