feat: allow aggregate ordering of through table edges

entgql/internal/todo/ent.graphql

@@ -1387,6 +1387,7 @@ Properties by which User connections can be ordered.
 """
 enum UserOrderField {
   GROUPS_COUNT
+  FRIENDS_COUNT
 }
 """
 UserWhereInput is used for filtering User objects.

entgql/internal/todo/ent/schema/user.go

@@ -55,7 +55,10 @@ func (User) Edges() []ent.Edge {
 			),
 		edge.To("friends", User.Type).
 			Through("friendships", Friendship.Type).
-			Annotations(entgql.RelayConnection()),
+			Annotations(
+				entgql.RelayConnection(),
+				entgql.OrderField("FRIENDS_COUNT"),
+			),
 	}
 }
 

entgql/internal/todo/todo_test.go

@@ -1989,6 +1989,84 @@ func TestMutation_ClearChildren(t *testing.T) {
 	require.False(t, root.QueryChildren().ExistX(ctx))
 }
 
+func TestQuery_SortUserByFriendshipsCount(t *testing.T) {
+	ec := enttest.Open(t, dialect.SQLite,
+		fmt.Sprintf("file:%s?mode=memory&cache=shared&_fk=1", t.Name()),
+		enttest.WithMigrateOptions(migrate.WithGlobalUniqueID(true)),
+	)
+	srv := handler.NewDefaultServer(gen.NewSchema(ec))
+	srv.Use(entgql.Transactioner{TxOpener: ec})
+	gqlc := client.New(srv)
+
+	ctx := context.Background()
+	user := ec.User.Create().SetRequiredMetadata(map[string]any{}).SaveX(ctx)
+	friend := ec.User.Create().SetRequiredMetadata(map[string]any{}).AddFriends(user).SaveX(ctx)
+	secondFriend := ec.User.Create().SetRequiredMetadata(map[string]any{}).AddFriends(user, friend).SaveX(ctx)
+	thirdFried := ec.User.Create().SetRequiredMetadata(map[string]any{}).AddFriends(user).SaveX(ctx)
+
+	require.True(t, user.QueryFriends().ExistX(ctx))
+	require.True(t, friend.QueryFriends().ExistX(ctx))
+	require.True(t, secondFriend.QueryFriends().ExistX(ctx))
+	require.True(t, thirdFried.QueryFriends().ExistX(ctx))
+
+	var rsp struct {
+		Users struct {
+			Edges []struct {
+				Node struct {
+					ID      string
+					Friends struct {
+						TotalCount int
+					}
+				}
+			}
+		}
+	}
+
+	query := `
+	query testThroughEdgeOrderByQuery($orderDirection: OrderDirection!) {
+		users (orderBy:{ field: FRIENDS_COUNT, direction: $orderDirection }) {
+            edges {
+                node {	
+                    id
+				    friends {
+                    	totalCount
+                    }
+                }
+           }
+		}
+	}
+	`
+
+	testCases := []struct {
+		direction          string
+		expectedCountOrder []int
+	}{
+		{
+			direction:          "DESC",
+			expectedCountOrder: []int{3, 2, 2, 1},
+		},
+		{
+			direction:          "ASC",
+			expectedCountOrder: []int{1, 2, 2, 3},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.direction, func(t *testing.T) {
+			err := gqlc.Post(
+				query,
+				&rsp,
+				client.Var("orderDirection", tc.direction))
+
+			require.NoError(t, err)
+			require.Len(t, rsp.Users.Edges, 4)
+			for i, edge := range rsp.Users.Edges {
+				require.Equal(t, edge.Node.Friends.TotalCount, tc.expectedCountOrder[i])
+			}
+		})
+	}
+}
+
 func TestMutation_ClearFriend(t *testing.T) {
 	ec := enttest.Open(t, dialect.SQLite,
 		fmt.Sprintf("file:%s?mode=memory&cache=shared&_fk=1", t.Name()),

entgql/template.go

@@ -452,12 +452,16 @@ func orderFields(n *gen.Type) ([]*OrderTerm, error) {
 			})
 		}
 	}
+	edgeNamesWithThroughTables := make(map[string]interface{})
 	for _, e := range n.Edges {
 		name := strings.ToUpper(e.Name)
 		switch ant, err := annotation(e.Annotations); {
 		case err != nil:
 			return nil, err
 		case ant.Skip.Is(SkipOrderField), ant.OrderField == "":
+		case strings.HasSuffix(ant.OrderField, "_COUNT") &&
+			edgeNamesWithThroughTables[strings.TrimSuffix(ant.OrderField, "_COUNT")] != nil:
+			// skip the through table annotations, annotations are applied on the `edge.To` edge instead
 		case ant.OrderField == fmt.Sprintf("%s_COUNT", name):
 			// Validate that the edge has a count ordering.
 			if _, err := e.OrderCountName(); err != nil {
@@ -471,7 +475,7 @@ func orderFields(n *gen.Type) ([]*OrderTerm, error) {
 				Count: true,
 			})
 		case strings.HasPrefix(ant.OrderField, name+"_"):
-			// Validate that the edge has a edge field ordering.
+			// Validate that the edge has an edge field ordering.
 			if _, err := e.OrderFieldName(); err != nil {
 				return nil, fmt.Errorf("entgql: invalid order field %s defined on edge %s.%s: %w", ant.OrderField, n.Name, e.Name, err)
 			}
@@ -493,6 +497,9 @@ func orderFields(n *gen.Type) ([]*OrderTerm, error) {
 		default:
 			return nil, fmt.Errorf("entgql: invalid order field defined on edge %s.%s", n.Name, e.Name)
 		}
+		if e.Through != nil {
+			edgeNamesWithThroughTables[name] = true
+		}
 	}
 	return terms, nil
 }

entgql/testdata/schema.graphql

@@ -313,4 +313,5 @@ Properties by which User connections can be ordered.
 """
 enum UserOrderField {
   GROUPS_COUNT
+  FRIENDS_COUNT
 }

entgql/testdata/schema_relay.graphql

@@ -1335,6 +1335,7 @@ Properties by which User connections can be ordered.
 """
 enum UserOrderField {
   GROUPS_COUNT
+  FRIENDS_COUNT
 }
 """
 UserWhereInput is used for filtering User objects.