using System;

namespace BLToolkit.Validation
{
    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
    public class RequiredAttribute : ValidatorBaseAttribute
    {
        public RequiredAttribute()
        {
        }

        public RequiredAttribute(string errorMessage)
            : base(errorMessage)
        {
        }

        public override bool IsValid(ValidationContext context)
        {
            return context.IsNull(context) == false;
        }

        public override string ErrorMessage
        {
            get { return base.ErrorMessage ?? "'{0}' is required."; }
            set { base.ErrorMessage = value; }
        }
    }
}