SmartMetadataProvider.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Web.Mvc;

namespace SmartStore.Web.Framework.Modelling
{
    /// <summary>
	/// This MetadataProvider adds some functionality on top of the default CachedDataAnnotationsModelMetadataProvider.
    /// It adds custom attributes (implementing IModelAttribute) to the AdditionalValues property of the model's metadata
    /// so that it can be retrieved later.
    /// </summary>
    public class SmartMetadataProvider : CachedDataAnnotationsModelMetadataProvider
    {
	    [SuppressMessage("ReSharper", "PossibleMultipleEnumeration")]
	    [SuppressMessage("ReSharper", "SuspiciousTypeConversion.Global")]
	    protected override CachedDataAnnotationsModelMetadata CreateMetadataPrototype(IEnumerable<Attribute> attributes, Type containerType, Type modelType, string propertyName)
		{
			var metadata = base.CreateMetadataPrototype(attributes, containerType, modelType, propertyName);
			var attrs = attributes.OfType<IModelAttribute>().ToList();

			foreach (var attr in attrs)
			{
				if (metadata.AdditionalValues.ContainsKey(attr.Name))
				{
					throw new SmartException("There is already an attribute with the name of '{0}' on this model.".FormatCurrent(attr.Name));
				}
				metadata.AdditionalValues.Add(attr.Name, attr);
			}

			return metadata;
		}

		protected override CachedDataAnnotationsModelMetadata CreateMetadataFromPrototype(CachedDataAnnotationsModelMetadata prototype, Func<object> modelAccessor)
		{
			var result = base.CreateMetadataFromPrototype(prototype, modelAccessor);

			if (prototype.AdditionalValues.Count > 0)
			{
				var attrs = prototype.AdditionalValues.Where(x => x.Value is IModelAttribute).ToArray();
				if (attrs.Any())
				{
					result.AdditionalValues.AddRange(attrs);
				}
			}

			return result;		
		}
    }
}