//
// RequiredAttribute.cs
//
// Author:
//	Atsushi Enomoto <atsushi@ximian.com>
//
// Copyright (C) 2008-2010 Novell Inc. http://novell.com
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.ComponentModel;

namespace System.ComponentModel.DataAnnotations
{
#if NET_4_0
	[AttributeUsage (AttributeTargets.Parameter|AttributeTargets.Property|AttributeTargets.Field, AllowMultiple = false)]
#else
	[AttributeUsage (AttributeTargets.Property|AttributeTargets.Field, AllowMultiple = false)]
#endif
	public class RequiredAttribute : ValidationAttribute
	{
#if NET_4_0
		public bool AllowEmptyStrings { get; set; }
#endif

		public override bool IsValid (object value)
		{
			if (value == null)
				return false;

			string s = value as string;
			if (s != null
#if NET_4_0
			    && !AllowEmptyStrings
#endif
			)
				return s.Length > 0;

			return true;
		}
	}
}