transaction_base.hxx

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/* Common code and definitions for the transaction classes.
 *
 * pqxx::transaction_base defines the interface for any abstract class that
 * represents a database transaction.
 *
 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/transaction_base instead.
 *
 * Copyright (c) 2000-2026, Jeroen T. Vermeulen.
 *
 * See COPYING for copyright license.  If you did not receive a file called
 * COPYING with this source code, please notify the distributor of this
 * mistake, or contact the author.
 */
#ifndef PQXX_TRANSACTION_BASE_HXX
#define PQXX_TRANSACTION_BASE_HXX
 
#if !defined(PQXX_HEADER_PRE)
#  error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
#endif
 
#include <string_view>
 
/* End-user programs need not include this file, unless they define their own
 * transaction classes.  This is not something the typical program should want
 * to do.
 *
 * However, reading this file is worthwhile because it defines the public
 * interface for the available transaction classes such as transaction and
 * nontransaction.
 */
 
#include "pqxx/connection.hxx"
#include "pqxx/encoding_group.hxx"
#include "pqxx/internal/stream_query.hxx"
#include "pqxx/isolation.hxx"
#include "pqxx/prepared_statement.hxx"
#include "pqxx/result.hxx"
#include "pqxx/row.hxx"
#include "pqxx/util.hxx"
 
namespace pqxx::internal::gate
{
class transaction_subtransaction;
class transaction_sql_cursor;
class transaction_stream_to;
class transaction_transaction_focus;
} // namespace pqxx::internal::gate
 
 
namespace pqxx
{
using namespace std::literals;
 
 
class transaction_focus;
 
 
 
class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base
{
public:
  transaction_base() = delete;
  transaction_base(transaction_base const &) = delete;
  transaction_base(transaction_base &&) = delete;
  transaction_base &operator=(transaction_base const &) = delete;
  transaction_base &operator=(transaction_base &&) = delete;
 
  virtual ~transaction_base() = 0;
 
 
  void commit(sl = sl::current());
 
 
  void abort(sl = sl::current());
 
  PQXX_ZARGS [[nodiscard]] std::string
  esc(char const str[], sl loc = sl::current())
  {
    return conn().esc(str, loc);
  }
 
  [[nodiscard]] std::string_view esc(
    std::string_view text, std::span<char> buffer,
    sl loc = sl::current()) const
  {
    return conn().esc(text, buffer, loc);
  }
 
  [[nodiscard]] std::string
  esc(std::string_view text, sl loc = sl::current()) const
  {
    return conn().esc(text, loc);
  }
 
  template<binary DATA> [[nodiscard]] std::string esc(DATA const &data) const
  {
    return conn().esc(data);
  }
 
 
  template<binary DATA>
  [[nodiscard]] zview
  esc(DATA const &data, std::span<char> buffer, sl loc = sl::current()) const
  {
    return conn().esc(data, buffer, loc);
  }
 
  template<binary DATA>
  [[nodiscard,
    deprecated("Use esc(), not esc_raw(), even on binary data.")]] zview
  esc_raw(DATA const &data, sl loc = sl::current()) const
  {
    return conn().esc(data, loc);
  }
 
  template<binary DATA>
  [[nodiscard,
    deprecated("Use esc(), not esc_raw(), even on binary data.")]] zview
  esc_raw(
    DATA const &data, std::span<char> buffer, sl loc = sl::current()) const
  {
    return conn().esc(data, buffer, loc);
  }
 
 
  [[nodiscard]] bytes unesc_bin(zview text, sl loc = sl::current())
  {
    return conn().unesc_bin(text, loc);
  }
 
 
  PQXX_ZARGS [[nodiscard]] bytes
  unesc_bin(char const text[], sl loc = sl::current())
  {
    return conn().unesc_bin(text, loc);
  }
 
  // TODO: "Into buffer" variant.
 
  template<typename T>
  [[nodiscard]] std::string quote(T const &t, sl loc = sl::current()) const
  {
    return conn().quote(t, loc);
  }
 
 
  template<binary DATA>
  [[nodiscard]] std::string
  quote_raw(DATA const &data, sl loc = sl::current()) const
  {
    return conn().quote_raw(data, loc);
  }
 
  // TODO: "Into buffer" variant.
  [[nodiscard]] std::string quote_name(std::string_view identifier) const
  {
    return conn().quote_name(identifier);
  }
 
  // TODO: "Into buffer" variant.
  [[nodiscard]] std::string esc_like(
    std::string_view bin, char escape_char = '\\',
    sl loc = sl::current()) const
  {
    return conn().esc_like(bin, escape_char, loc);
  }
 
 
 
  [[deprecated("The desc parameter is going away.")]]
  result
  exec(std::string_view query, std::string_view desc, sl = sl::current());
 
  // TODO: Wrap PQdescribePrepared().
 
  result
  exec(std::string_view query, params const &parms, sl loc = sl::current())
  {
    return internal_exec_params(query, parms.make_c_params(loc), loc);
  }
 
 
  result exec(std::string_view query, sl = sl::current());
 
 
  [[deprecated(
    "Pass your query as a std::string_view, not stringstream.")]] result
  exec(std::stringstream const &query, std::string_view desc)
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return exec(query.str(), desc);
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }
 
 
  [[deprecated("Use exec(string_view) and call no_rows() on the result.")]]
  result exec0(std::string_view query, std::string_view desc)
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return exec(query, desc).no_rows();
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }
 
 
  [[deprecated("Use exec() and call no_rows() on the result.")]]
  result exec0(std::string_view query)
  {
    return exec(query).no_rows();
  }
 
 
  [[deprecated("Use exec(string_view), and call one_row() on the result.")]]
  row exec1(std::string_view query, std::string_view desc)
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return exec(query, desc).one_row();
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }
 
 
  [[deprecated("Use exec() instead, and call one_row() on the result.")]]
  row exec1(std::string_view query)
  {
    return exec(query).one_row();
  }
 
 
  [[deprecated("Use exec() instead, and call expect_rows() on the result.")]]
  result exec_n(
    result::size_type rows, std::string_view query, std::string_view desc);
 
 
  [[deprecated("Use exec() instead, and call expect_rows() on the result.")]]
  result exec_n(result::size_type rows, std::string_view query)
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return exec(query, std::string_view{}).expect_rows(rows);
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }
 
 
  template<not_borrowed TYPE>
  [[deprecated("The desc parameter is going away.")]]
  TYPE query_value(std::string_view query, std::string_view desc)
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return exec(query, desc).one_field().as<TYPE>();
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }
 
 
  template<not_borrowed TYPE>
  TYPE query_value(std::string_view query, sl loc = sl::current())
  {
    // The result and field_ref objects are temporaries, but under C++20
    // lifetime rules they'll live until after we convert the field to TYPE.
    return exec(query, loc).one_field_ref(loc).as<TYPE>(loc);
  }
 
 
  template<not_borrowed... TYPE>
  [[nodiscard]] std::tuple<TYPE...>
  query1(std::string_view query, sl loc = sl::current())
  {
    // The result and row_ref objects are temporaries, but under C++20 lifetime
    // rules they'll live until after we convert the field to TYPE.
    return exec(query, loc)
      .expect_columns(sizeof...(TYPE), loc)
      .one_row_ref(loc)
      .as<TYPE...>(loc);
  }
 
 
  template<not_borrowed... TYPE>
  [[nodiscard]] std::optional<std::tuple<TYPE...>>
  query01(std::string_view query, sl loc = sl::current())
  {
    auto const res{exec(query, loc)};
    std::optional<row_ref> const r{res.opt_row_ref(loc)};
    if (r)
      return {r->as<TYPE...>(loc)};
    else
      return {};
  }
 
 
  template<std::move_constructible... TYPE>
  [[nodiscard]] auto stream(std::string_view query, sl loc = sl::current()) &
  {
    return pqxx::internal::stream_query<TYPE...>{
      *this, query, make_context(loc)};
  }
 
 
  template<typename CALLABLE>
  auto
  for_stream(std::string_view query, CALLABLE &&func, sl loc = sl::current())
  {
    // TODO: Can we pass loc into func if appropriate?
    using param_types =
      pqxx::internal::strip_types_t<pqxx::internal::args_t<CALLABLE>>;
    param_types const *const sample{nullptr};
    auto data_stream{stream_like(query, sample, loc)};
    for (auto const &fields : data_stream) std::apply(func, fields);
  }
 
  template<typename CALLABLE>
  [[deprecated(
    "pqxx::transaction_base::for_each is now called for_stream.")]] auto
  for_each(std::string_view query, CALLABLE &&func, sl loc = sl::current())
  {
    return for_stream(query, std::forward<CALLABLE>(func), loc);
  }
 
 
  template<typename... TYPE>
  auto query(std::string_view query, sl loc = sl::current())
  {
    return exec(query, loc).iter<TYPE...>();
  }
 
  template<typename... TYPE>
  [[deprecated("Use query() instead, and call expect_rows() on the result.")]]
  auto query_n(
    result::size_type rows, std::string_view query, sl loc = sl::current())
  {
    return exec(query, loc).expect_rows(rows, loc).iter<TYPE...>();
  }
 
 
  template<typename CALLABLE>
  void
  for_query(std::string_view query, CALLABLE &&func, sl loc = sl::current())
  {
    exec(query).for_each(std::forward<CALLABLE>(func), loc);
  }
 
 
 
  template<typename... Args>
  [[deprecated("Use exec(std::string_view, params) instead.")]]
  result exec_params(std::string_view query, Args &&...args)
  {
    return exec(query, params{*this, args...}, sl::current());
  }
 
  // Execute parameterised statement, expect a single-row result.
  template<typename... Args>
  [[deprecated("Use exec() instead, and call one_row() on the result.")]]
  row exec_params1(std::string_view query, Args &&...args)
  {
    return exec(query, params{*this, args...}).one_row();
  }
 
  // Execute parameterised statement, expect a result with zero rows.
  template<typename... Args>
  [[deprecated(
    "Use exec(string_view, params) and call no_rows() on the result.")]]
  result exec_params0(std::string_view query, Args &&...args)
  {
    return exec(query, params{*this, args...}).no_rows();
  }
 
  // Execute parameterised statement, expect exactly a given number of rows.
  template<typename... Args>
  [[deprecated("Use exec(), and call expect_rows() on the result.")]]
  result
  exec_params_n(std::size_t rows, std::string_view query, Args &&...args)
  {
    sl const loc{m_created_loc};
    return exec(query, params{*this, args...}, loc)
      .expect_rows(
        check_cast<result_size_type>(rows, "number of rows", loc), loc);
  }
 
  // Execute parameterised statement, expect exactly a given number of rows.
  template<typename... Args>
  [[deprecated("Use exec(), and call expect_rows() on the result.")]]
  result
  exec_params_n(result::size_type rows, std::string_view query, Args &&...args)
  {
    return exec(query, params{*this, args...}).expect_rows(rows);
  }
 
 
  template<typename... TYPE>
  auto
  query(std::string_view query, params const &parms, sl loc = sl::current())
  {
    return exec(query, parms, loc).iter<TYPE...>();
  }
 
 
  template<typename... TYPE>
  [[deprecated("Use exec(), and call expect_rows() & iter() on the result.")]]
  auto
  query_n(result::size_type rows, std::string_view query, params const &parms)
  {
    return exec(query, parms).expect_rows(rows).iter<TYPE...>();
  }
 
 
  template<not_borrowed TYPE>
  TYPE query_value(
    std::string_view query, params const &parms, sl loc = sl::current())
  {
    // The result and field_ref objects are temporaries, but under C++20
    // lifetime rules they'll live until after we convert the field to TYPE.
    return exec(query, parms, loc)
      .expect_columns(1, loc)
      .one_field_ref(loc)
      .as<TYPE>(loc);
  }
 
 
  template<not_borrowed... TYPE>
  [[nodiscard]]
  std::tuple<TYPE...>
  query1(std::string_view query, params const &parms, sl loc = sl::current())
  {
    // The result and row_ref objects are temporaries, but under C++20 lifetime
    // rules they'll live until after we convert the field to TYPE.
    return exec(query, parms, loc).one_row_ref(loc).as<TYPE...>(loc);
  }
 
 
  template<not_borrowed... TYPE>
  [[nodiscard]] std::optional<std::tuple<TYPE...>>
  query01(std::string_view query, params const &parms, sl loc = sl::current())
  {
    auto const res{exec(query, parms, loc)};
    std::optional<row_ref> r{res.opt_row_ref(loc)};
    if (r)
      return {r->as<TYPE...>(loc)};
    else
      return {};
  }
 
 
  template<typename CALLABLE>
  void for_query(
    std::string_view query, CALLABLE &&func, params const &parms,
    sl loc = sl::current())
  {
    exec(query, parms, loc).for_each(std::forward<CALLABLE>(func), loc);
  }
 
 
  void notify(
    std::string_view channel, std::string_view payload, sl = sl::current());
 
 
  void notify(std::string_view channel, sl loc = sl::current())
  {
    notify(channel, {}, loc);
  }
 
  template<typename... Args>
  [[deprecated("Use exec(prepped, params) instead.")]]
  result exec_prepared(zview statement, Args &&...args)
  {
    return exec(prepped{statement}, params{*this, args...});
  }
 
  result exec(prepped statement, sl loc = sl::current())
  {
    params const pp;
    return internal_exec_prepared(statement, pp.make_c_params(loc), loc);
  }
 
 
  template<typename... TYPE>
  auto query(prepped statement, params const &parms, sl loc = sl::current())
  {
    return exec(statement, parms, loc).iter<TYPE...>();
  }
 
 
  template<typename... TYPE>
  auto query(prepped statement, sl loc = sl::current())
  {
    return exec(statement, {}, loc).iter<TYPE...>();
  }
 
 
  template<not_borrowed TYPE>
  TYPE
  query_value(prepped statement, params const &parms, sl loc = sl::current())
  {
    // The result and field_ref objects are temporaries, but under C++20
    // lifetime rules they'll live until after we convert the field to TYPE.
    return exec(statement, parms, loc)
      .expect_columns(1, loc)
      .one_field_ref(loc)
      .as<TYPE>(loc);
  }
 
 
  template<not_borrowed TYPE>
  TYPE query_value(prepped statement, sl loc = sl::current())
  {
    return exec(statement, {}, loc)
      .expect_columns(1, loc)
      .one_field_ref(loc)
      .as<TYPE>(loc);
  }
 
 
  template<typename CALLABLE>
  void for_query(
    prepped statement, CALLABLE &&func, params const &parms,
    sl loc = sl::current())
  {
    exec(statement, parms, loc).for_each(std::forward<CALLABLE>(func), loc);
  }
 
 
  template<typename CALLABLE>
  void for_query(prepped statement, CALLABLE &&func, sl loc = sl::current())
  {
    exec(statement, {}, loc).for_each(std::forward<CALLABLE>(func), loc);
  }
 
  result exec(prepped statement, params const &parms, sl loc = sl::current())
  {
    return internal_exec_prepared(statement, parms.make_c_params(loc), loc);
  }
 
 
  template<typename... Args>
  [[deprecated(
    "Use exec(string_view, params) and call one_row() on the result.")]]
  row exec_prepared1(zview statement, Args &&...args)
  {
    sl const loc{m_created_loc};
    return exec(prepped{statement}, params{*this, args...}).one_row(loc);
  }
 
 
  template<typename... Args>
  [[deprecated(
    "Use exec(prepped, params), and call no_rows() on the result.")]]
  result exec_prepared0(zview statement, Args &&...args)
  {
    sl const loc{m_created_loc};
    return exec(prepped{statement}, params{*this, args...}).no_rows(loc);
  }
 
 
  template<typename... Args>
  [[deprecated(
    "Use exec(prepped, params), and call expect_rows() on the result.")]]
  result
  exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
  {
    sl const loc{m_created_loc};
    return exec(pqxx::prepped{statement}, params{*this, args...})
      .expect_rows(rows, loc);
  }
 
  PQXX_ZARGS void process_notice(char const msg[]) const
  {
    m_conn.process_notice(msg);
  }
  void process_notice(zview msg) const { m_conn.process_notice(msg); }
 
  [[nodiscard]] constexpr connection &conn() const noexcept { return m_conn; }
 
 
  [[deprecated("Set transaction-local variables using SQL SET statements.")]]
  void set_variable(std::string_view var, std::string_view value);
 
 
  [[deprecated("Read variables using SQL SHOW statements.")]]
  std::string get_variable(std::string_view);
 
  [[nodiscard]] constexpr std::string_view name() const & noexcept
  {
    return m_name;
  }
 
protected:
 
  transaction_base(
    connection &, std::string_view, std::shared_ptr<std::string> rollback_cmd,
    sl loc = sl::current());
 
 
  transaction_base(
    connection &cx, std::string_view tname, sl loc = sl::current());
 
  explicit transaction_base(connection &cx, sl loc = sl::current());
 
  void register_transaction();
 
  void close(sl = sl::current()) noexcept;
 
  virtual void do_commit(sl) = 0;
 
 
  virtual void do_abort(sl);
 
  void set_rollback_cmd(std::shared_ptr<std::string> cmd)
  {
    m_rollback_cmd = std::move(cmd);
  }
 
  result direct_exec(std::string_view, std::string_view desc, sl);
  result direct_exec(std::string_view query, sl loc)
  {
    return direct_exec(query, "", loc);
  }
  result direct_exec(std::shared_ptr<std::string>, std::string_view desc, sl);
  result direct_exec(std::shared_ptr<std::string> query, sl loc)
  {
    return direct_exec(std::move(query), "", loc);
  }
 
  // TODO: Can this be noexcept?
  [[nodiscard]] sl created_loc() const { return m_created_loc; }
 
private:
  enum class status
  {
    active,
    aborted,
    committed,
    in_doubt
  };
 
 
  [[nodiscard]] conversion_context make_context(sl) const;
 
  PQXX_PRIVATE void check_pending_error();
 
  result internal_exec_prepared(
    std::string_view statement, internal::c_params const &args, sl);
 
  result internal_exec_params(
    std::string_view query, internal::c_params const &args, sl);
 
  [[nodiscard]] std::string description() const;
 
  friend class pqxx::internal::gate::transaction_transaction_focus;
  PQXX_PRIVATE void register_focus(transaction_focus *);
  PQXX_PRIVATE void unregister_focus(transaction_focus *) noexcept;
  PQXX_PRIVATE void register_pending_error(zview, sl) noexcept;
  PQXX_PRIVATE void register_pending_error(std::string &&, sl) noexcept;
 
  template<typename... ARGS>
  auto stream_like(
    std::string_view query, std::tuple<ARGS...> const *,
    sl loc = sl::current())
  {
    return stream<ARGS...>(query, loc);
  }
 
  connection &m_conn;
 
 
  transaction_focus const *m_focus = nullptr;
 
  std::string m_name;
  std::string m_pending_error;
 
  std::shared_ptr<std::string> m_rollback_cmd;
 
  status m_status = status::active;
 
  bool m_registered = false;
 
  sl m_created_loc;
 
  static constexpr std::string_view s_type_name{"transaction"sv};
};
} // namespace pqxx
 
 
namespace pqxx::internal
{
template<pqxx::isolation_level isolation, pqxx::write_policy rw>
extern const zview begin_cmd;
 
// These are not static members, so "constexpr" does not imply "inline".
template<>
inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
  "BEGIN"_zv};
template<>
inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
  "BEGIN READ ONLY"_zv};
template<>
inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
  "BEGIN ISOLATION LEVEL REPEATABLE READ"_zv};
template<>
inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
  "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"_zv};
template<>
inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
  "BEGIN ISOLATION LEVEL SERIALIZABLE"_zv};
template<>
inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
  "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"_zv};
} // namespace pqxx::internal
 
#include "pqxx/internal/stream_query_impl.hxx"
#endif