Fix for Issue #87 Error when mapping expression with generic IEnumerable.Contains.

Author: BlaiseD

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
 
     - name: Set Variables
       run: |
-        echo '::set-env name=VERSION_NUMBER::4.0.1-preview-3'
+        echo '::set-env name=VERSION_NUMBER::4.0.1-preview-4'
         echo '::set-env name=DEPLOY_PACKAGE_URL::https://www.myget.org/F/automapperdev/api/v3/index.json'
         echo '::set-env name=DEPLOY_PACKAGE_API_KEY::${{ secrets.MYGET_CI_API_KEY }}'
         echo '::set-env name=REPO::${{ github.repository }}'

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
 
     - name: Set Variables
       run: |
-        echo '::set-env name=VERSION_NUMBER::4.0.1-preview-3'
+        echo '::set-env name=VERSION_NUMBER::4.0.1-preview-4'
         echo '::set-env name=DEPLOY_PACKAGE_URL::https://api.nuget.org/v3/index.json'
         echo '::set-env name=DEPLOY_PACKAGE_API_KEY::${{ secrets.NUGET_API_KEY }}'
         echo '::set-env name=REPO::${{ github.repository }}'

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <Authors>Jimmy Bogard</Authors>
     <LangVersion>latest</LangVersion>
-    <VersionPrefix>4.0.1-preview-3</VersionPrefix>
+    <VersionPrefix>4.0.1-preview-4</VersionPrefix>
     <WarningsAsErrors>true</WarningsAsErrors>
     <NoWarn>$(NoWarn);1701;1702;1591</NoWarn>
   </PropertyGroup>

src/AutoMapper.Extensions.ExpressionMapping/MapperExtensions.cs

@@ -375,6 +375,11 @@ private static void DoAddTypeMappings(this Dictionary<Type, Type> typeMappings,
             }
         }
 
+        private static Type GetSourceMemberType(this PropertyMap propertyMap)
+            => propertyMap.CustomMapExpression != null
+                ? propertyMap.CustomMapExpression.ReturnType
+                : propertyMap.SourceMember.GetMemberType();
+
         private static void FindChildPropertyTypeMaps(this Dictionary<Type, Type> typeMappings, IConfigurationProvider ConfigurationProvider, Type source, Type dest)
         {
             //The destination becomes the source because to map a source expression to a destination expression,
@@ -395,7 +400,7 @@ void FindMaps(List<PropertyMap> maps)
                     AddChildMappings
                     (
                         source.GetFieldOrProperty(pm.DestinationMember.Name).GetMemberType(),
-                        pm.SourceMember.GetMemberType()
+                        pm.GetSourceMemberType()
                     );
                     void AddChildMappings(Type sourcePropertyType, Type destPropertyType)
                     {

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/EnumerableDotContainsWorksOnLocalVariables.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+using Xunit;
+
+namespace AutoMapper.Extensions.ExpressionMapping.UnitTests
+{
+    public class EnumerableDotContainsWorksOnLocalVariables
+    {
+        [Fact]
+        public void Issue87()
+        {
+            var config = new MapperConfiguration(cfg =>
+            {
+                cfg.AddExpressionMapping();
+
+                cfg.CreateMap<Source, SourceDto>()
+                    .ForMember(o => o.Items, config => config.MapFrom(p => p.Items.Select(s => s.Name)));
+            });
+
+            var mapper = config.CreateMapper();
+
+            var items = new string[] { "item1", "item2" };
+            Expression<Func<SourceDto, bool>> expression1 = o => items.Contains("");
+            Expression<Func<SourceDto, bool>> expression2 = o => o.Items.Contains("");
+
+            var mapped1 = mapper.MapExpression<Expression<Func<Source, bool>>>(expression1);
+            var mapped2 = mapper.MapExpression<Expression<Func<Source, bool>>>(expression2);
+
+            Assert.NotNull(mapped1);
+            Assert.NotNull(mapped2);
+        }
+
+        public class Source { public ICollection<SubSource> Items { get; set; } }
+
+        public class SubSource { public int ID { get; set; } public string Name { get; set; } }
+
+        public class SourceDto { public string[] Items { get; set; } }
+    }
+}