Allowed collections to be inherited from Base Types

GraphDiff/GraphDiff.Tests/Models/TestModels.cs

@@ -147,6 +147,25 @@ public class NullableKeyModel
         public Guid? Id { get; set; }
     }
 
+    // Generic Collection models:
+    public class SimpleTitleModel
+    {
+        [Key]
+        public string Title { get; set; }
+    }
+
+    public class CollectionFromListModel : List<SimpleTitleModel>
+    {
+
+    }
+
+    public class CollectionFromListEntity : Entity
+    {
+        public CollectionFromListModel CollectionItems { get; set; }
+
+        public List<SimpleTitleModel> SimpleTitleItems { get; set; }
+    }
+
     // ====================================
     // Second tier models
     // ====================================

GraphDiff/GraphDiff.Tests/TestDbContext.cs

@@ -38,6 +38,8 @@ public class TestDbContext : DbContext
         public IDbSet<OneToOneOwnedParentModel> OneToOneOwnedParentModels { get; set; }
         public IDbSet<OneToManyOwnedParentModel> OneToManyOwnedParentModels { get; set; }
 
+        public IDbSet<CollectionFromListEntity> CollectionFromListEntities { get; set; }
+
         public TestDbContext() : base("GraphDiff") { }
         public TestDbContext(DbConnection connection) : base(connection, true) { }
 

GraphDiff/GraphDiff.Tests/Tests/OwnedCollectionBehaviours.cs

@@ -415,5 +415,44 @@ public void ShouldUpdateOwnedCollectionElementWithTwoParents()
                 Assert.AreEqual(secondParent.Id, attachedChild.SecondParent.Id);
             }
         }
+
+        [TestMethod]
+        public void ShouldWorkWithListEntities()
+        {
+            var source = new CollectionFromListEntity()
+            {
+                CollectionItems = new CollectionFromListModel()
+                {
+                    new SimpleTitleModel() { Title = "Test" }
+                },
+                SimpleTitleItems = new List<SimpleTitleModel>()
+                {
+                    new SimpleTitleModel() { Title = "Old" }
+                }
+            };
+            using (var context = new TestDbContext())
+            {
+                context.CollectionFromListEntities.Add(source);
+                context.SaveChanges();
+            }
+
+            var newExpectedCollectionValue = "New Collection Value";
+            var newExpectedSimpleValue = "New Simple Value";
+            source.CollectionItems[0].Title = newExpectedCollectionValue;
+            source.SimpleTitleItems[0].Title = newExpectedSimpleValue;
+
+            using (var context = new TestDbContext())
+            {
+                context.UpdateGraph(source, map => map.OwnedCollection(c => c.CollectionItems).OwnedCollection(c => c.SimpleTitleItems));
+                context.SaveChanges();
+
+                var reloaded = context.CollectionFromListEntities
+                    .Include(x => x.CollectionItems)
+                    .Include(x => x.SimpleTitleItems).FirstOrDefault(c => c.Id == source.Id);
+
+                Assert.AreEqual(newExpectedCollectionValue, reloaded.CollectionItems[0].Title);
+                Assert.AreEqual(newExpectedSimpleValue, reloaded.SimpleTitleItems[0].Title);
+            }
+        }
     }
 }

GraphDiff/GraphDiff/Internal/Graph/CollectionGraphNode.cs

@@ -142,7 +142,13 @@ private Type GetCollectionElementType()
                 return Accessor.PropertyType.GetGenericArguments()[0];
             }
 
-            throw new InvalidOperationException("GraphDiff requires the collection to be either IEnumerable<T> or T[]");
+            var baseType = Accessor.PropertyType.BaseType;
+            if (baseType != null && baseType.IsGenericType)
+            {
+                return baseType.GetGenericArguments()[0];
+            }
+
+            throw new InvalidOperationException("GraphDiff requires the collection to be either IEnumerable<T> or T[] or derived from GenericType");
         }
     }
 }