Add a Mapping Processor Adapter

src/MongoFramework/Attributes/MappingAdapterAttribute.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Runtime.InteropServices;
+using MongoFramework.Infrastructure.Mapping;
+
+namespace MongoFramework.Attributes
+{
+	/// <summary>
+	/// Allows an IMappingProcessor to override definitions in code.  Runs after attribute processing, so the adapter can override attributes.
+	/// Adapter type must have a parameterless constructor.
+	/// </summary>
+	[AttributeUsage(AttributeTargets.Class)]
+	public class MappingAdapterAttribute : Attribute
+	{
+		/// <summary>
+		/// Gets the adapter type for the attached class
+		/// </summary>
+		public Type MappingAdapter { get; }
+
+		public MappingAdapterAttribute(Type adapterType)
+		{
+			if (!typeof(IMappingProcessor).IsAssignableFrom(adapterType))
+			{
+				throw new ArgumentException("Mapping Adapter Type must implement IMappingProcessor", nameof(adapterType));
+			}
+
+			MappingAdapter = adapterType;
+		}
+	}
+}

src/MongoFramework/Infrastructure/Mapping/DefaultMappingPack.cs

@@ -16,7 +16,8 @@ public static class DefaultProcessors
 			new DecimalSerializationProcessor(),
 			new TypeDiscoveryProcessor(),
 			new BsonKnownTypesProcessor(),
-			new IndexProcessor()
+			new IndexProcessor(),
+			new MappingAdapterProcessor()
 		};
 	}
 }

src/MongoFramework/Infrastructure/Mapping/Processors/MappingAdapterProcessor.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Reflection;
+using System.Text;
+using MongoDB.Bson.Serialization;
+using MongoFramework.Attributes;
+
+namespace MongoFramework.Infrastructure.Mapping.Processors
+{
+	public class MappingAdapterProcessor : IMappingProcessor
+	{
+		public void ApplyMapping(IEntityDefinition definition, BsonClassMap classMap)
+		{
+			var adapterAttribute = definition.EntityType.GetCustomAttribute<MappingAdapterAttribute>();
+
+			if (adapterAttribute == null)				
+			{
+				return;
+			}
+
+			var instance = (IMappingProcessor)Activator.CreateInstance(adapterAttribute.MappingAdapter);
+
+			if (instance != null)
+			{
+				instance.ApplyMapping(definition, classMap);
+			}
+
+		}
+	}
+}

tests/MongoFramework.Tests/Infrastructure/Mapping/Processors/MappingAdapterProcessorTests.cs

@@ -0,0 +1,115 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.IdGenerators;
+using MongoFramework.Attributes;
+using MongoFramework.Infrastructure.Mapping;
+using MongoFramework.Infrastructure.Mapping.Processors;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Linq;
+
+namespace MongoFramework.Tests.Infrastructure.Mapping.Processors
+{
+	[TestClass]
+	public class MappingAdapterProcessorTests : MappingTestBase
+	{
+
+		public class AdapterTestModelMappingAdapter : IMappingProcessor
+		{
+			public void ApplyMapping(IEntityDefinition definition, BsonClassMap classMap)
+			{
+				definition.CollectionName = "Custom";
+
+				var definitionIndexes = definition.Indexes.ToList();
+
+				definitionIndexes.Add(new EntityIndex
+				{					
+					Property = definition.GetProperty("UserName"),
+					IsUnique = true,
+					SortOrder = IndexSortOrder.Ascending
+				});
+
+				definition.Indexes = definitionIndexes;
+			}
+		}
+
+		[Table("TestModels")]
+		[MappingAdapter(typeof(AdapterTestModelMappingAdapter))]
+		public class AdapterTestModel
+		{
+			public Guid MyCustomId { get; set; }
+			public string UserName { get; set; }
+
+		}
+
+		public class AdapterTestModelMappingAdapterNoInterface
+		{
+			// no interface
+		}
+
+		[MappingAdapter(typeof(AdapterTestModelMappingAdapterNoInterface))]
+		public class AdapterTestModelNoInterface
+		{
+			// broken adapter 
+		}
+
+		public class AdapterTestModelMappingAdapterConstructor : IMappingProcessor
+		{
+			public AdapterTestModelMappingAdapterConstructor(string test)
+			{
+
+			}
+
+			public void ApplyMapping(IEntityDefinition definition, BsonClassMap classMap)
+			{
+				throw new NotImplementedException();
+			}
+		}
+
+		[MappingAdapter(typeof(AdapterTestModelMappingAdapterConstructor))]
+		public class AdapterTestModelConstructor
+		{
+			// broken adapter 
+		}
+
+		[TestMethod]
+		public void AdapterRequiresIMappingProcessor()
+		{
+			EntityMapping.AddMappingProcessor(new CollectionNameProcessor());
+			EntityMapping.AddMappingProcessor(new PropertyMappingProcessor());
+			EntityMapping.AddMappingProcessor(new EntityIdProcessor());
+			EntityMapping.AddMappingProcessor(new MappingAdapterProcessor());
+			Assert.ThrowsException<ArgumentException>(() => EntityMapping.RegisterType(typeof(AdapterTestModelNoInterface)));
+		}
+
+		[TestMethod]
+		public void AdapterRequiresParameterlessConstructor()
+		{
+			EntityMapping.AddMappingProcessor(new CollectionNameProcessor());
+			EntityMapping.AddMappingProcessor(new PropertyMappingProcessor());
+			EntityMapping.AddMappingProcessor(new EntityIdProcessor());
+			EntityMapping.AddMappingProcessor(new MappingAdapterProcessor());
+			Assert.ThrowsException<MissingMethodException>(() => EntityMapping.RegisterType(typeof(AdapterTestModelConstructor)));
+		}
+
+		[TestMethod]
+		public void AdapterOverridesAttributes()
+		{
+			EntityMapping.AddMappingProcessor(new CollectionNameProcessor());
+			EntityMapping.AddMappingProcessor(new PropertyMappingProcessor());
+			EntityMapping.AddMappingProcessor(new EntityIdProcessor());
+			EntityMapping.AddMappingProcessor(new MappingAdapterProcessor());
+			var definition = EntityMapping.RegisterType(typeof(AdapterTestModel));
+
+			Assert.AreEqual("Custom", definition.CollectionName);
+			Assert.AreEqual(1, definition.Indexes.Count());
+
+
+
+		}
+
+	}
+}