Fix support for cast in $expand - expand some property on derived type only

AutoMapper.AspNetCore.OData.EF6/QueryableExtensions.cs

@@ -169,7 +169,7 @@ private static IQueryable<TModel> GetQueryable<TModel, TData>(this IQueryable<TD
             Expression<Func<TModel, bool>> filter)
             where TModel : class
         {
-            var expansions = options.SelectExpand.GetExpansions(typeof(TModel));
+            var expansions = options.SelectExpand.GetExpansions(typeof(TModel), options.Context.Model);
 
             return query.GetQuery
             (

AutoMapper.AspNetCore.OData.EFCore/LinqExtensions.cs

@@ -11,6 +11,9 @@
 
 namespace AutoMapper.AspNet.OData
 {
+    using Microsoft.OData.Edm;
+    using Microsoft.OData.ModelBuilder;
+
     public static class LinqExtensions
     {
         /// <summary>
@@ -498,23 +501,32 @@ private static List<string> GetIncludes(this IEnumerable<SelectItem> selectedIte
             });
         }
 
-        public static List<List<ODataExpansionOptions>> GetExpansions(this SelectExpandQueryOption clause, Type parentType)
+        public static List<List<ODataExpansionOptions>> GetExpansions(
+            this SelectExpandQueryOption clause,
+            Type parentType,
+            IEdmModel edmModel)
         {
             if (clause?.SelectExpandClause == null)
                 return new List<List<ODataExpansionOptions>>();
 
-            return clause.SelectExpandClause.SelectedItems.GetExpansions(parentType);
+            return clause.SelectExpandClause.SelectedItems.GetExpansions(parentType, edmModel);
         }
 
-        private static List<List<ODataExpansionOptions>> GetNestedExpansions(this ExpandedNavigationSelectItem node, Type type)
+        private static List<List<ODataExpansionOptions>> GetNestedExpansions(
+            this ExpandedNavigationSelectItem node,
+            Type type,
+            IEdmModel edmModel)
         {
             if (node == null)
                 return new List<List<ODataExpansionOptions>>();
 
-            return node.SelectAndExpand.SelectedItems.GetExpansions(type);
+            return node.SelectAndExpand.SelectedItems.GetExpansions(type, edmModel);
         }
 
-        private static List<List<ODataExpansionOptions>> GetExpansions(this IEnumerable<SelectItem> selectedItems, Type parentType)
+        private static List<List<ODataExpansionOptions>> GetExpansions(
+            this IEnumerable<SelectItem> selectedItems,
+            Type parentType,
+            IEdmModel edmModel)
         {
             if (selectedItems == null)
                 return new List<List<ODataExpansionOptions>>();
@@ -524,6 +536,13 @@ private static List<List<ODataExpansionOptions>> GetExpansions(this IEnumerable<
                 string path = next.PathToNavigationProperty.FirstSegment.Identifier;//Only first segment is necessary because of the new syntax $expand=Builder($expand=City) vs $expand=Builder/City
 
                 Type currentParentType = parentType.GetCurrentType();
+
+                if (next.PathToNavigationProperty.FirstSegment is TypeSegment) { //Handle cast in $expand
+                    path = next.PathToNavigationProperty.LastSegment.Identifier;
+                    ClrTypeAnnotation annotation = edmModel.GetAnnotationValue<ClrTypeAnnotation>(next.PathToNavigationProperty.FirstSegment.EdmType);
+                    currentParentType = annotation.ClrType;
+                }
+
                 Type memberType = currentParentType.GetMemberInfo(path).GetMemberType();
                 Type elementType = memberType.GetCurrentType();
 
@@ -537,7 +556,7 @@ private static List<List<ODataExpansionOptions>> GetExpansions(this IEnumerable<
                     Selects = next.SelectAndExpand.GetSelects()
                 };
 
-                List<List<ODataExpansionOptions>> navigationItems = next.GetNestedExpansions(elementType).Select
+                List<List<ODataExpansionOptions>> navigationItems = next.GetNestedExpansions(elementType, edmModel).Select
                 (
                     expansions =>
                     {

AutoMapper.AspNetCore.OData.EFCore/QueryableExtensions.cs

@@ -126,8 +126,8 @@ private static IQueryable<TModel> GetQueryable<TModel, TData>(this IQueryable<TD
             Expression<Func<TModel, bool>> filter)
             where TModel : class
         {
-            
-            var expansions = options.SelectExpand.GetExpansions(typeof(TModel));
+
+            var expansions = options.SelectExpand.GetExpansions(typeof(TModel), options.Context.Model);
 
             return query.GetQuery
             (