MVC: Override default ValidationMessage

Question

In the world of MVC I have this view model...

public class MyViewModel{

[Required]
public string FirstName{ get; set; }    }

...and this s

Answer 1

You can write your own attribute:

public class MyRequiredAttribute : ValidationAttribute
{
    MyRequiredAttribute() : base(() => "{0} blah blah blah blaaaaaah")
    {

    }

    public override bool IsValid(object value)
    {
        if (value == null)
        {
            return false;
        }
        string str = value as string;
        if (str != null)
        {
            return (str.Trim().Length != 0);
        }
        return true;
    }
}

This is copy of RequiredAttribute from Reflector with changed error message.