Is it possible to override the required attribute on a property in a model?

Question

I\'m curious to find out if it is possible to override the [Required] attribute that has been set on a model. I\'m sure there most be a simple solution to this problem, any

Answer 1

You can use a custom validation attribute (it might be derived from RequiredAttribute):

 public class RequiredExAttribute : RequiredAttribute
    {
        public bool UseRequiredAttribute { get; protected set; }
        public RequiredExAttribute(bool IsRequired)
        {
            UseRequiredAttribute = IsRequired;
        }
        public override bool IsValid(object value)
        {
            if (UseRequiredAttribute)
                return base.IsValid(value);
            else
            {
                return true;
            }
        }

        public override bool RequiresValidationContext
        {
            get
            {
                return UseRequiredAttribute;
            }
        }
    }

    public class RequiredExAttributeAdapter : RequiredAttributeAdapter
    {
        public RequiredExAttributeAdapter(ModelMetadata metadata, ControllerContext context, RequiredExAttribute attribute)
            : base(metadata, context, attribute) { }

        public override IEnumerable GetClientValidationRules()
        {
            if (((RequiredExAttribute)Attribute).UseRequiredAttribute)// required -> return normal required rules
                return base.GetClientValidationRules();
            else// not required -> return empty rules list
                return new List();
        }
    }

and then regester it in Application_Start using this code line:

 DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(RequiredExAttribute), typeof(RequiredExAttributeAdapter));