COM Interop Object Mapper for AutoMapper 6

ComObjectMapper.cs

using AutoMapper;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Linq.Expressions;
using AutoMapper.Execution;
using AutoMapper.Internal;
using System.Reflection;

namespace Anamespace
{
    class ComObjectMapper : IObjectMapper
    {
        private static readonly Func<ITypeInfo, Guid> GetTypeInfoGuid = (Func<ITypeInfo, Guid>)Delegate.CreateDelegate(typeof(Func<ITypeInfo, Guid>), typeof(Marshal).GetMethod("GetTypeInfoGuid", BindingFlags.NonPublic | BindingFlags.Static), throwOnBindFailure: true);
        private static readonly Type ComObjectType = typeof(object).Assembly.GetType("System.__ComObject");
        private static readonly Dictionary<Guid, Type> typesByGuid = GetTypes();

        private static Dictionary<Guid, Type> GetTypes()
        {
            var types =
                from assembly in AppDomain.CurrentDomain.GetAssemblies()
                from type in assembly.ExportedTypes
                where type.IsInterface && type.IsImport
                select type;
            var typesByGuid = new Dictionary<Guid, Type>();
            foreach (var type in types)
            {
                typesByGuid[type.GUID] = type;
            }
            return typesByGuid;
        }

        /// <summary>
        /// Exposes objects, methods and properties to programming tools and other
        /// applications that support Automation.
        /// </summary>
        [ComImport()]
        [Guid("00020400-0000-0000-C000-000000000046")]
        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        interface IDispatch
        {
            [PreserveSig]
            int GetTypeInfoCount(out int Count);

            ITypeInfo GetTypeInfo([MarshalAs(UnmanagedType.U4)] int iTInfo, [MarshalAs(UnmanagedType.U4)] int lcid);

            [PreserveSig]
            int GetIDsOfNames(
                ref Guid riid,
                [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPWStr)]
            string[] rgsNames,
                int cNames,
                int lcid,
                [MarshalAs(UnmanagedType.LPArray)] int[] rgDispId);

            [PreserveSig]
            int Invoke(
                int dispIdMember,
                ref Guid riid,
                uint lcid,
                ushort wFlags,
                ref System.Runtime.InteropServices.ComTypes.DISPPARAMS pDispParams,
                out object pVarResult,
                ref System.Runtime.InteropServices.ComTypes.EXCEPINFO pExcepInfo,
                IntPtr[] pArgErr);
        }

        public static Type GetComObjectType(object comObject)
        {
            if (!Marshal.IsComObject(comObject))
            {
                throw new ArgumentOutOfRangeException(nameof(comObject), "Expected a COM object.");
            }
            var dispatch = (IDispatch)comObject;
            var typeInfo = dispatch.GetTypeInfo(0, 0);
            var typeGuid = GetTypeInfoGuid(typeInfo);
            return typesByGuid[typeGuid];
        }

        public bool IsMatch(TypePair context)
        {
            return context.SourceType == ComObjectType;
        }

        public static Exception MissingMapException(Type sourceType, Type destinationType)
        {
            var source = sourceType.Name;
            var destination = destinationType.Name;
            throw new InvalidOperationException($"Missing map from {source} to {destination}. Create using Mapper.CreateMap<{source}, {destination}>.");
        }

        public Expression MapExpression(IConfigurationProvider configurationProvider, ProfileMap profileMap, PropertyMap propertyMap, Expression sourceExpression, Expression destExpression, Expression contextExpression)
        {
            var sourceObject = ExpressionFactory.ToObject(sourceExpression);
            var sourceType = GetComObjectType(sourceObject);

            return TypeMapPlanBuilder.MapExpression(configurationProvider, profileMap,
                    new TypePair(sourceType, destExpression.Type),
                    sourceExpression,
                    contextExpression,
                    propertyMap,
                    destExpression
                );
        }
    }
}

Hi Jakub,

The MapExpression method above needs to be changed to accommodate changes for AutoMapper 7.0.1. It needs to be changed to:

        public Expression MapExpression(IConfigurationProvider configurationProvider, ProfileMap profileMap, PropertyMap propertyMap, Expression sourceExpression, Expression destExpression, Expression contextExpression)
        {
            var sourceObject = ExpressionFactory.ToObject(sourceExpression);
            var sourceType = GetComObjectType(sourceObject);

            return ExpressionBuilder.MapExpression(configurationProvider, profileMap,
                    new TypePair(sourceType, destExpression.Type),
                    sourceExpression,
                    contextExpression,
                    propertyMap,
                    destExpression
                );
        }

Thanks!