Cast to the appropriate type an object passed to IsValid method

Question

Edition:

I leave this question for the sake of archiving but tbh I should probably delete it. It was my complete fault, I was doing several things wrong. First of all I reused the code from a RequiredIf validation but I should remove the _innerAttribute and the most inner if related to it that I forgot to do. And the main thing is that I was trying to compare an enum to a string and that's why it was failing but the code actually works fine if I pass to the constructor the appropriate enum member. I was misunderstanding completely the behaviour of object, casts...

End of edition

I'm trying to write a custom validation attribute that disallows a field to be set to a particular value if another one is not null. I've written this (I ommit the part for implementing the IClientVAlidatable)

public class NotAllowedIfNotNullAttribute : ValidationAttribute, IClientValidatable
{
    private readonly RequiredAttribute _innerAttribute = new RequiredAttribute();

    public string DependentProperty { get; set; }
    public object NotAllowedValue { get; set; }

    public NotAllowedIfNotNullAttribute(string dependentProperty, object notAllowedValue)
    {
        DependentProperty = dependentProperty;
        NotAllowedValue = notAllowedValue;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var typedValue = CastValue(value, _valueType)
        ;
        var containerType = validationContext.ObjectInstance.GetType();

        var field = containerType.GetProperty(DependentProperty);

        if (field != null)
        {
            var dependentvalue = field.GetValue(validationContext.ObjectInstance, null);

            if ((dependentvalue != null && value.Equals(NotAllowedValue)))
            {
                if (!_innerAttribute.IsValid(value))
                    return new ValidationResult(ErrorMessage, new[] { validationContext.MemberName });
            }
        }

        return ValidationResult.Success;
    }
    //.....
}

My problems is value.Equals(NotAllowedValue), how could I get the value casted to the notAllowedValue type? I've tried to pass the type as a paremeter but I would need to work more in that approach as I had no luck for the moment

Thanks!

Have a look at the answer for this question: http://stackoverflow.com/questions/4332635/c-sharp-compare-two-objects-of-unknown-types-including-reference-and-value-type — Daniel J.G., Jun 07 '13 at 15:14
check this http://stackoverflow.com/questions/1398796/casting-with-reflection — Gonzalo.-, Jun 07 '13 at 15:18

score 0 · Answer 1 · answered Jun 07 '13 at 15:23

Maybe you should try to use a template?

public class NotAllowedIfNotNullAttribute<T> : ValidationAttribute, IClientValidatable
    {
        private readonly RequiredAttribute _innerAttribute = new RequiredAttribute();

        public string DependentProperty { get; set; }
        public T NotAllowedValue { get; set; }

        public NotAllowedIfNotNullAttribute(string dependentProperty, T notAllowedValue)
        {
            DependentProperty = dependentProperty;
            NotAllowedValue = notAllowedValue;
        }

        protected override ValidationResult IsValid(T value, ValidationContext validationContext)
...

A generic type cannot derive from "ValidationAttribute" because it is an attribute class. Thanks! — mitomed, Jun 07 '13 at 15:37

Cast to the appropriate type an object passed to IsValid method

1 Answers1