.NET: ModelStateDictionary Adapter?

Question

So, I've been messing around with validation in .NET, trying to find a good solid way of implementing validation in a business layer (such as discussed in this MSDN article).

The idea is that I pass a controller's ModelState to the business service, and then the service performs validation and updates the ModelState.

However, one thing I've noticed is that ModelStateDictionary exists in two different namespaces:

• System.Web.Http.Modelbinding
• System.Web.MVC

While I could just "pick one", I don't want my business layer to have any dependencies on the presentation layer. For instance, if I picked MVC the business service classes would need to expect the MVC-namespaced version of ModelStateDictionary...meaning they would be dependent on an MVC presentation layer.

So, I was wondering if anybody had suggestions on how to approach this?

My attempt was to create an adapter/Inteface IModelStateDictionary, and I got close... But, the Modelstate uses a ValueProviderResult class (also System.Web.MVC) that has a virtual method ConvertTo(). I'm not sure how I can get around this...might be a simple pattern I haven't learned, yet, but at my level of experience am not sure if it's really a show stopper...

...or that I could approach this in a better way?

Advice would be Most Appreciated!

Thanks,

Chris

Edit: Code below

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Common.Interfaces
{
    public interface IModelStateDictionary
    {
        IModelState this[string key] { get; set; }
        int Count { get; }      
        bool IsReadOnly { get; }       
        bool IsValid { get; }      
        ICollection<string> Keys { get; }       
        ICollection<IModelState> Values { get; }
        void Add(KeyValuePair<string, IModelState> item);      
        void Add(string key, IModelState value);        
        void AddModelError(string key, string errorMessage);       
        void AddModelError(string key, Exception exception);       
        bool Contains(KeyValuePair<string, IModelState> item);        
        bool ContainsKey(string key);       
        void CopyTo(KeyValuePair<string, IModelState>[] array, int arrayIndex);      
        IEnumerator<KeyValuePair<string, IModelState>> GetEnumerator();        
        bool IsValidField(string key);       
        void Merge(IModelStateDictionary dictionary);      
        bool Remove(string key);     
        bool Remove(KeyValuePair<string, IModelState> item);     
        void SetModelValue(string key, IValueProviderResult value);    
        bool TryGetValue(string key, out IModelState value);
    }

    public interface IModelState
    {
        IModelErrorCollection Errors { get; }
        IValueProviderResult Value { get; set; }
    }

    public interface IValueProviderResult
    {
        string AttemptedValue { get; protected set; }
        CultureInfo Culture { get; protected set; }
        object RawValue { get; protected set; }
        object ConvertTo(Type type);
        virtual object ConvertTo(Type type, CultureInfo culture);
    }

    public interface IModelErrorCollection
    {
        void Add(string errorMessage);
        void Add(Exception exception);
    }

}