DatabaseExecutor.hpp

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#pragma once
 
#include <iostream>
#include <string>
#include <utility>
#include <vector>
 
#include "ConnectionPool.hpp"
#include "RowDTOAdapter.hpp"

class DatabaseExecutor {
  public:
    explicit DatabaseExecutor(ConnectionPool& pool) noexcept : pool_(pool) {
    }
 
    DatabaseExecutor(const DatabaseExecutor&) = delete;
    DatabaseExecutor& operator=(const DatabaseExecutor&) = delete;
 
    [[nodiscard]] bool hasConnection() const noexcept {
        return pool_.has_connection();
    }
 
    template <typename... Types>
    [[nodiscard]] bool execQuery(const std::string& query, Types&&... args);
 
    template <typename... Types>
    [[nodiscard]] RowDTOAdapter execSelect(const std::string& query, Types&&... args);
 
    template <typename... Types>
    [[nodiscard]] std::vector<RowDTOAdapter> execSelectAll(const std::string& query, Types&&... args);
 
  private:
    ConnectionPool& pool_;
};
 
template <typename... Types>
[[nodiscard]] bool DatabaseExecutor::execQuery(const std::string& query, Types&&... args) {
    int times = 0;
    while (times <= 10) {
        auto lease = pool_.acquire();
        if (not lease) {
            return false;
        }
        try {
            NativeDatabase::Transaction txn(lease.get());
            const NativeDatabase::ParameterList params{std::forward<Types>(args)...};
            (void)txn.exec(query, params);
            txn.commit();
            return true;
        } catch (const NativeDatabase::BrokenConnectionException&) {
            lease.discard();
            ++times;
        } catch (const std::exception& e) {
            std::cerr << "Error: " << e.what() << "\nInvalid exec for query:\n" << query << '\n';
            return false;
        }
    }
    return false;
}
 
template <typename... Types>
[[nodiscard]] RowDTOAdapter DatabaseExecutor::execSelect(const std::string& query, Types&&... args) {
    int times = 0;
    while (times <= 10) {
        auto lease = pool_.acquire();
        if (not lease) {
            return {NativeDatabase::Row{}};
        }
        try {
            NativeDatabase::Transaction txn(lease.get());
            const NativeDatabase::ParameterList params{std::forward<Types>(args)...};
            const NativeDatabase::Result result = txn.exec(query, params);
            txn.commit();
            if (result.empty()) {
                return {NativeDatabase::Row{}};
            }
            return {result[0]};
        } catch (const NativeDatabase::BrokenConnectionException&) {
            lease.discard();
            ++times;
        } catch (const std::exception& e) {
            std::cerr << "Error: " << e.what() << "\nInvalid selection for query:\n" << query << '\n';
            return {NativeDatabase::Row{}};
        }
    }
    return {NativeDatabase::Row{}};
}
 
template <typename... Types>
[[nodiscard]] std::vector<RowDTOAdapter> DatabaseExecutor::execSelectAll(const std::string& query, Types&&... args) {
    int times = 0;
    while (times <= 10) {
        auto lease = pool_.acquire();
        if (not lease) {
            return {};
        }
        try {
            NativeDatabase::Transaction txn(lease.get());
            const NativeDatabase::ParameterList params{std::forward<Types>(args)...};
            const NativeDatabase::Result result = txn.exec(query, params);
            txn.commit();
            std::vector<RowDTOAdapter> selection;
            selection.reserve(static_cast<std::size_t>(result.size()));
            for (const auto& row : result) {
                selection.emplace_back(row);
            }
            return selection;
        } catch (const NativeDatabase::BrokenConnectionException&) {
            lease.discard();
            ++times;
        } catch (const std::exception& e) {
            std::cerr << "Error: " << e.what() << "\nInvalid selection for query:\n" << query << '\n';
            return {};
        }
    }
    return {};
}