feat: add bought check

backend/app/models/users.go

@@ -322,6 +322,29 @@ func (m *usersModel) GetUsersMapByIDs(ctx context.Context, ids []int64) (map[int
 	}), nil
 }
 
+func (m *usersModel) BatchCheckHasBought(ctx context.Context, userID int64, postIDs []int64) (map[int64]bool, error) {
+	tbl := table.UserPosts
+	stmt := tbl.SELECT(tbl.PostID.AS("post_id")).WHERE(
+		tbl.UserID.EQ(Int64(userID)).AND(
+			tbl.PostID.IN(lo.Map(postIDs, func(id int64, _ int) Expression { return Int64(id) })...),
+		),
+	)
+
+	var userPosts []struct {
+		PostID int64
+	}
+	if err := stmt.QueryContext(ctx, db, &userPosts); err != nil {
+		m.log.Errorf("error querying user posts: %v", err)
+		return nil, err
+	}
+
+	result := make(map[int64]bool)
+	for _, post := range userPosts {
+		result[post.PostID] = true
+	}
+	return result, nil
+}
+
 // HasBought
 func (m *usersModel) HasBought(ctx context.Context, userID, postID int64) (bool, error) {
 	tbl := table.UserPosts