Function BuildPaginationLinks

Modules/RESTAPI/src/mitkDataStorageController.cpp:148–204

* @brief Build pagination links from request and query result. * * @param req The original request. * @param limit The pagination limit. * @param offset The current offset. * @param totalCount Total number of items. * @param returnedCount Number of items returned in this response. * @return JSON object with "prev" and "next" links (if applicable). */

   * @return JSON object with "prev" and "next" links (if applicable).
   */
  nlohmann::json BuildPaginationLinks(
    const httplib::Request& req,
    int limit,
    int offset,
    int totalCount,
    int returnedCount)
  {
    nlohmann::json links = nlohmann::json::object();

    // Build base URL from request path
    std::string basePath = req.path;

    // Collect query parameters, excluding offset (we'll set it ourselves)
    std::vector<std::pair<std::string, std::string>> preservedParams;
    for (const auto& param : req.params)
    {
      if (param.first != "offset")
      {
        preservedParams.push_back(param);
      }
    }

    // Build query string helper
    auto buildUrl = [&basePath, &preservedParams](int newOffset) -> std::string {
      std::ostringstream url;
      url << basePath << "?";

      bool first = true;
      for (const auto& param : preservedParams)
      {
        if (!first) url << "&";
        url << param.first << "=" << param.second;
        first = false;
      }

      if (!first) url << "&";
      url << "offset=" << newOffset;

      return url.str();
    };

    // Previous page link (only if not at the beginning)
    if (offset > 0)
    {
      int prevOffset = std::max(0, offset - limit);
      links["prev"] = buildUrl(prevOffset);
    }

    // Next page link (only if there are more items)
    if (offset + returnedCount < totalCount)
    {
      int nextOffset = offset + limit;
      links["next"] = buildUrl(nextOffset);
    }

    return links;
  }