server/src/database.cppm


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export module routemon:database;

import std;
import :sqlite3;

namespace routemon::database {

  static constexpr std::int64_t expected_database_version = 1;

  export class connection {
    sqlite3::connection dbc_;

    explicit connection(sqlite3::connection dbc) : dbc_{std::move(dbc)} {}

    friend auto open(std::string const& filename) -> std::shared_ptr<connection>;

  public:
    // Nothing here yet
  };

  export auto open(std::string const& filename) -> std::shared_ptr<connection> {
    auto dbc = sqlite3::open(filename);
    try {
      auto version = std::optional<std::int64_t>{};
      dbc.query("SELECT version FROM migration;").scan_single(version);
      if (!version)
        throw std::runtime_error{"failed to fetch database migration version"};
      if (version != expected_database_version) {
        throw std::runtime_error{std::format("database migration version ({}) does not match expected version ({}), consider running migrations", *version, expected_database_version)};
      }
    } catch (std::exception const& e) {
      throw std::runtime_error{std::format("failed to query database version: {}", e.what())};
    }
    return std::shared_ptr<connection>{new connection{std::move(dbc)}};
  }

} // namespace routemon::database