update changes based on review comments

Author: ElizabethOkerio

src/Microsoft.AspNetCore.OData/Query/Expressions/BinderExtensions.cs

@@ -275,7 +275,10 @@ public static IQueryable ApplyBind(this ISelectExpandBinder binder, IQueryable s
                 throw Error.ArgumentNull(nameof(context));
             }
 
-            context.QueryProvider = source.Provider.GetType().Namespace;
+            if (string.IsNullOrEmpty(context.QueryProvider))
+            {
+                context.QueryProvider = source.Provider.GetType().Namespace;
+            }
 
             Type elementType = context.ElementClrType;
 

src/Microsoft.AspNetCore.OData/Query/Expressions/SelectExpandBinder.cs

@@ -444,6 +444,7 @@ private Expression UpdateMemberInitExpression(Expression source, IEdmStructuredT
             if (QueryProvider != null &&
                 QueryProvider == HandleNullPropagationOptionHelper.EntityFrameworkQueryProviderNamespace ||
                 QueryProvider == HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEF5 ||
+                QueryProvider == HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEF6 ||
                 QueryProvider == HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEFCore2)
             {
                 Type elementType = source.Type;

test/Microsoft.AspNetCore.OData.Tests/Query/Expressions/SelectExpandBinderTest.cs

@@ -203,12 +203,52 @@ public void Bind_GeneratedExpression_ContainsExpandedObject()
                 .ToDictionary(PropertyMapper)["Orders"] as IEnumerable<SelectExpandWrapper<QueryOrder>>;
             Assert.NotNull(innerOrders);
             SelectExpandWrapper<QueryOrder> partialOrder = innerOrders.Single();
+            var tt = _queryable.First().Orders.First();
+            var xx = _queryable.First();
             Assert.Same(_queryable.First().Orders.First(), partialOrder.Instance);
             object customer = partialOrder.Container.ToDictionary(PropertyMapper)["Customer"];
             SelectExpandWrapper<QueryCustomer> innerInnerCustomer = Assert.IsAssignableFrom<SelectExpandWrapper<QueryCustomer>>(customer);
             Assert.Same(_queryable.First(), innerInnerCustomer.Instance);
         }
 
+        [Theory]
+        [InlineData(HandleNullPropagationOptionHelper.EntityFrameworkQueryProviderNamespace)]
+        [InlineData(HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEFCore2)]
+        [InlineData(HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEF5)]
+        [InlineData(HandleNullPropagationOptionHelper.ObjectContextQueryProviderNamespaceEF6)]
+        public void Bind_UsingEFQueryProvider_GeneratedExpression_ContainsExpandedObject(string queryProvider)
+        {
+            // Arrange
+            SelectExpandQueryOption selectExpand = new SelectExpandQueryOption("Orders", "Orders,Orders($expand=Customer)", _context);
+
+            // Act
+            SelectExpandBinder binder = new SelectExpandBinder();
+            _queryBinderContext.QueryProvider = queryProvider;
+            IQueryable queryable = binder.ApplyBind(_queryable, selectExpand.SelectExpandClause, _queryBinderContext);
+
+            // Assert
+            IEnumerator enumerator = queryable.GetEnumerator();
+            Assert.True(enumerator.MoveNext());
+            var partialCustomer = Assert.IsAssignableFrom<SelectExpandWrapper<QueryCustomer>>(enumerator.Current);
+            Assert.False(enumerator.MoveNext());
+            Assert.Null(partialCustomer.Instance);
+            Assert.Equal("Microsoft.AspNetCore.OData.Tests.Query.Expressions.QueryCustomer", partialCustomer.InstanceType);
+            IEnumerable<SelectExpandWrapper<QueryOrder>> innerOrders = partialCustomer.Container
+                .ToDictionary(PropertyMapper)["Orders"] as IEnumerable<SelectExpandWrapper<QueryOrder>>;
+            Assert.NotNull(innerOrders);
+            SelectExpandWrapper<QueryOrder> partialOrder = innerOrders.Single();
+            
+            // We only write structural properties to the instance.
+            // This means that navigation properties on the instance property will be null
+            // when using any instance of EF query provider. 
+            Assert.Null(partialOrder.Instance.Customer);
+
+            object customer = partialOrder.Container.ToDictionary(PropertyMapper)["Customer"];
+            SelectExpandWrapper<QueryCustomer> innerInnerCustomer = Assert.IsAssignableFrom<SelectExpandWrapper<QueryCustomer>>(customer);
+
+            Assert.Null(innerInnerCustomer.Instance.Orders);
+        }
+
         [Fact]
         public void Bind_GeneratedExpression_CheckNullObjectWithinChainProjectionByKey()
         {