利用DataAnnotations验证实体(类)的属性

.NET 4 和Silverlight 中可以使用以下方法:

public static void Validate(this Entity entity)
{
    // prepare the result
    var validationResults = new List<ValidationResult>();
    // create a validation context
    var validationContext = new ValidationContext(entity, null, null);
    // validate
    Validator.TryValidateObject(entity, validationContext, validationResults);
    // reset the validation errors of the entity
    entity.ValidationErrors.Clear();
    foreach (var error in validationResults)
        entity.ValidationErrors.Add(error);
}

.NET 3.5中的方法：

	public static class EntityValidator
	{
		public static IEnumerable<ErrorField> GetErrors(object instance)
		{
			var t = instance.GetType();
			var typeDescriptor = new AssociatedMetadataTypeTypeDescriptionProvider(t).GetTypeDescriptor(t);

			return from prop in typeDescriptor.GetProperties().Cast<PropertyDescriptor>()
					 from attribute in prop.Attributes.OfType<ValidationAttribute>()
					 where !attribute.IsValid(prop.GetValue(instance))
					 select new ErrorField(prop.Name, attribute.FormatErrorMessage(string.Empty));
		}	
	}

	[Serializable]
	public class ErrorField
	{
		public string ID { get; set; }
		
		public string Msg { get; set; }

		public ErrorField(string id, string msg)
		{
			this.ID = id;
			this.Msg = msg;
		}


	}