Property validation

Question

I require that the Feature set of my Licence to have a non-empty intersection with a set of features that the module I am loading contains. I expect other lists in my License to form similar requirements, and I wish to be able to specify as much information as possible on the license object, i.e. I do not wish to need to update the Validator if the contents of the License object changes.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Linq.Expressions;
namespace Testing
{
 public class License
 {
 [CollectionIntersects]
 public List<string> Features { get; set; } 
 }
 [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
 public abstract class LicenseValidator:Attribute
 {
 public abstract bool isValid(object context, object obj, PropertyInfo property);
 }
 public class Validator
 {
 public static bool isValid(object context, object obj)
 {
 bool valid = true;
 Type objType = obj.GetType();
 PropertyInfo[] props = objType.GetProperties();
 foreach (PropertyInfo prop in props)
 {
 foreach (LicenseValidator validator in prop.GetCustomAttributes<LicenseValidator>())
 {
 valid=valid&&validator.isValid(context, obj, prop);
 }
 }
 return valid;
 }
 }
 public class CollectionIntersects: LicenseValidator
 {
 public CollectionIntersects()
 {
 }
 public override bool isValid(object context, object obj, PropertyInfo property)
 {
 Type collectionType = property.PropertyType;
 Object contextvalue = property.GetValue(context);
 Object objectvalue = property.GetValue(obj);
 //Casting code lifted from
 //http://stackoverflow.com/a/31380177/1986513.
 var param = Expression.Parameter(typeof(object));
 dynamic contextvalueenum =
 Expression.Lambda(Expression.Convert(param, collectionType), param).Compile().DynamicInvoke(contextvalue);
 dynamic licencevalueenum =
 Expression.Lambda(Expression.Convert(param, collectionType), param).Compile().DynamicInvoke(objectvalue);
 return ((IEnumerable<object>)Enumerable.Intersect(contextvalueenum, licencevalueenum)).Any();
 }
 }
}

Is there an easier way to accomplish this? Also, how sensitive is it to localization and collation issues considering that the license might be written in a different locale than the reference context object?

Answer 1

Self answer, one nights sleep later.

A simpler solution can be made by making the arguments of the function dynamic. The isValid method can then be written as;

 public override bool isValid(dynamic context, dynamic obj, PropertyInfo property)
 {
 return ((IEnumerable<object>)Enumerable.Intersect(property.GetValue(context), property.GetValue(obj))).Any();
 }