Merge pull request #3187 from AutoMapper/enumerable-projections

Match destination enumerable types with it's enumerable for LINQ

src/AutoMapper/QueryableExtensions/Impl/EnumerableExpressionBinder.cs

@@ -2,7 +2,6 @@
 using System.Linq;
 using System.Linq.Expressions;
 using AutoMapper.Configuration;
-using AutoMapper.Mappers;
 using AutoMapper.Mappers.Internal;
 
 namespace AutoMapper.QueryableExtensions.Impl
@@ -29,17 +28,22 @@ private static MemberAssignment BindEnumerableExpression(IConfigurationProvider
                 {
                     return null;
                 }
-                expression = transformedExpressions.Aggregate(expression, (source, lambda) => Select(source, lambda));
+                expression = transformedExpressions.Aggregate(expression, Select);
             }
 
-            expression = Expression.Call(typeof(Enumerable), propertyMap.DestinationType.IsArray ? "ToArray" : "ToList", new[] { destinationListType }, expression);
+            expression =
+                propertyMap.DestinationType.IsArray
+                    ? Expression.Call(typeof(Enumerable), nameof(Enumerable.ToArray), new[] {destinationListType}, expression) 
+                    : propertyMap.DestinationType.IsCollectionType()
+                        ? Expression.Call(typeof(Enumerable), nameof(Enumerable.ToList), new[] {destinationListType}, expression)
+                        : expression;
 
             return Expression.Bind(propertyMap.DestinationMember, expression);
         }
 
         private static Expression Select(Expression source, LambdaExpression lambda)
         {
-            return Expression.Call(typeof(Enumerable), "Select", new[] { lambda.Parameters[0].Type, lambda.ReturnType }, source, lambda);
+            return Expression.Call(typeof(Enumerable), nameof(Enumerable.Select), new[] { lambda.Parameters[0].Type, lambda.ReturnType }, source, lambda);
         }
     }
 }

src/IntegrationTests/IEnumerableMemberProjections.cs

@@ -0,0 +1,89 @@
+using System.ComponentModel.DataAnnotations;
+using System.Data.Entity;
+using System.Linq;
+using Shouldly;
+using Xunit;
+
+namespace AutoMapper.IntegrationTests
+{
+    using UnitTests;
+    using QueryableExtensions;
+    using System.Collections.Generic;
+
+    public class IEnumerableMemberProjections : AutoMapperSpecBase
+    {
+        public class Customer
+        {
+            [Key]
+            public int Id { get; set; }
+            public string FirstName { get; set; }
+            public string LastName { get; set; }
+            public ICollection<Item> Items { get; set; }
+        }
+
+        public class Item
+        {
+            public int Id { get; set; }
+            public int Code { get; set; }
+        }
+
+        public class ItemModel
+        {
+            public int Id { get; set; }
+            public int Code { get; set; }
+        }
+
+        public class CustomerViewModel
+        {
+            public IEnumerable<ItemModel> Items { get; set; }
+        }
+
+        public class Context : DbContext
+        {
+            public Context()
+            {
+                Database.SetInitializer<Context>(new DatabaseInitializer());
+            }
+
+            public DbSet<Customer> Customers { get; set; }
+        }
+
+        public class DatabaseInitializer : DropCreateDatabaseAlways<Context>
+        {
+            protected override void Seed(Context context)
+            {
+                context.Customers.Add(new Customer
+                {
+                    Id = 1,
+                    FirstName = "Bob",
+                    LastName = "Smith",
+                    Items = new[] { new Item { Code = 1 }, new Item { Code = 3 }, new Item { Code = 5 } }
+                });
+
+                base.Seed(context);
+            }
+        }
+
+        public class CustomerItemCodes
+        {
+            public IEnumerable<int> ItemCodes { get; set; }
+        }
+
+        protected override MapperConfiguration Configuration => new MapperConfiguration(cfg =>
+            {
+                cfg.CreateMap<Customer, CustomerViewModel>();
+                cfg.CreateMap<Item, ItemModel>();
+            });
+
+        [Fact]
+        public void Can_map_to_ienumerable()
+        {
+            using (var context = new Context())
+            {
+                var result = ProjectTo<CustomerViewModel>(context.Customers).Single();
+
+                result.Items.Count().ShouldBe(3);
+            }
+        }
+    }
+}