Fix ExtractList to support extraction from generic api.List{}

pkg/runtime/helper.go

@@ -41,10 +41,14 @@ func GetItemsPtr(list Object) (interface{}, error) {
 	if !items.IsValid() {
 		return nil, fmt.Errorf("no Items field in %#v", list)
 	}
-	if items.Kind() != reflect.Slice {
+	switch items.Kind() {
-		return nil, fmt.Errorf("Items field is not a slice")
+	case reflect.Interface, reflect.Ptr:
+		return items.Interface(), nil
+	case reflect.Slice:
+		return items.Addr().Interface(), nil
+	default:
+		return nil, fmt.Errorf("items: Expected slice, got %s", items.Kind())
 	}
-	return items.Addr().Interface(), nil
 }
 
 // ExtractList returns obj's Items element as an array of runtime.Objects.
@@ -61,11 +65,16 @@ func ExtractList(obj Object) ([]Object, error) {
 	list := make([]Object, items.Len())
 	for i := range list {
 		raw := items.Index(i)
-		item, ok := raw.Addr().Interface().(Object)
+		var found bool
-		if !ok {
+		switch raw.Kind() {
-			return nil, fmt.Errorf("item[%v]: Expected object, got %#v", i, raw.Interface())
+		case reflect.Interface, reflect.Ptr:
+			list[i], found = raw.Interface().(Object)
+		default:
+			list[i], found = raw.Addr().Interface().(Object)
+		}
+		if !found {
+			return nil, fmt.Errorf("item[%v]: Expected object, got %#v(%s)", i, raw.Interface(), raw.Kind())
 		}
-		list[i] = item
 	}
 	return list, nil
 }

pkg/runtime/helper_test.go

@@ -63,6 +63,74 @@ func TestExtractList(t *testing.T) {
 	}
 }
 
+func TestExtractListGeneric(t *testing.T) {
+	pl := &api.List{
+		Items: []runtime.Object{
+			&api.Pod{ObjectMeta: api.ObjectMeta{Name: "1"}},
+			&api.Service{ObjectMeta: api.ObjectMeta{Name: "2"}},
+		},
+	}
+	list, err := runtime.ExtractList(pl)
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	if e, a := len(list), len(pl.Items); e != a {
+		t.Fatalf("Expected %v, got %v", e, a)
+	}
+	if obj, ok := list[0].(*api.Pod); !ok {
+		t.Fatalf("Expected list[0] to be *api.Pod, it is %#v", obj)
+	}
+	if obj, ok := list[1].(*api.Service); !ok {
+		t.Fatalf("Expected list[1] to be *api.Service, it is %#v", obj)
+	}
+}
+
+type fakePtrInterfaceList struct {
+	Items []*runtime.Object
+}
+
+func (f fakePtrInterfaceList) IsAnAPIObject() {}
+
+func TestExtractListOfInterfacePtrs(t *testing.T) {
+	pl := &fakePtrInterfaceList{
+		Items: []*runtime.Object{},
+	}
+	list, err := runtime.ExtractList(pl)
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	if len(list) > 0 {
+		t.Fatalf("Expected empty list, got %#v", list)
+	}
+}
+
+type fakePtrValueList struct {
+	Items []*api.Pod
+}
+
+func (f fakePtrValueList) IsAnAPIObject() {}
+
+func TestExtractListOfValuePtrs(t *testing.T) {
+	pl := &fakePtrValueList{
+		Items: []*api.Pod{
+			{ObjectMeta: api.ObjectMeta{Name: "1"}},
+			{ObjectMeta: api.ObjectMeta{Name: "2"}},
+		},
+	}
+	list, err := runtime.ExtractList(pl)
+	if err != nil {
+		t.Fatalf("Unexpected error %v", err)
+	}
+	if e, a := len(list), len(pl.Items); e != a {
+		t.Fatalf("Expected %v, got %v", e, a)
+	}
+	for i := range list {
+		if obj, ok := list[i].(*api.Pod); !ok {
+			t.Fatalf("Expected list[%d] to be *api.Pod, it is %#v", i, obj)
+		}
+	}
+}
+
 func TestSetList(t *testing.T) {
 	pl := &api.PodList{}
 	list := []runtime.Object{