libpqxx 7.8.0
transaction_base.hxx
1/* Common code and definitions for the transaction classes.
2 *
3 * pqxx::transaction_base defines the interface for any abstract class that
4 * represents a database transaction.
5 *
6 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/transaction_base instead.
7 *
8 * Copyright (c) 2000-2023, Jeroen T. Vermeulen.
9 *
10 * See COPYING for copyright license. If you did not receive a file called
11 * COPYING with this source code, please notify the distributor of this
12 * mistake, or contact the author.
13 */
14#ifndef PQXX_H_TRANSACTION_BASE
15#define PQXX_H_TRANSACTION_BASE
16
17#if !defined(PQXX_HEADER_PRE)
18# error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
19#endif
20
21#include <string_view>
22
23/* End-user programs need not include this file, unless they define their own
24 * transaction classes. This is not something the typical program should want
25 * to do.
26 *
27 * However, reading this file is worthwhile because it defines the public
28 * interface for the available transaction classes such as transaction and
29 * nontransaction.
30 */
31
32#include "pqxx/connection.hxx"
33#include "pqxx/internal/concat.hxx"
34#include "pqxx/internal/encoding_group.hxx"
35#include "pqxx/internal/stream_query.hxx"
36#include "pqxx/isolation.hxx"
37#include "pqxx/result.hxx"
38#include "pqxx/row.hxx"
39#include "pqxx/util.hxx"
40
42{
43class transaction_subtransaction;
44class transaction_sql_cursor;
45class transaction_stream_to;
46class transaction_transaction_focus;
47} // namespace pqxx::internal::gate
48
49
50namespace pqxx
51{
52using namespace std::literals;
53
54
55class transaction_focus;
56
57
82
87class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base
88{
89public:
90 transaction_base() = delete;
95
96 virtual ~transaction_base() = 0;
97
99
112 void commit();
113
115
118 void abort();
119
131 template<typename... ARGS> [[nodiscard]] auto esc(ARGS &&...args) const
132 {
133 return conn().esc(std::forward<ARGS>(args)...);
134 }
135
137
148 template<typename... ARGS> [[nodiscard]] auto esc_raw(ARGS &&...args) const
149 {
150 return conn().esc_raw(std::forward<ARGS>(args)...);
151 }
152
154
157 [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
158 unesc_raw(zview text) const
159 {
160#include "pqxx/internal/ignore-deprecated-pre.hxx"
161 return conn().unesc_raw(text);
162#include "pqxx/internal/ignore-deprecated-post.hxx"
163 }
164
166
169 [[nodiscard]] std::basic_string<std::byte> unesc_bin(zview text)
170 {
171 return conn().unesc_bin(text);
172 }
173
175
178 [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
179 unesc_raw(char const *text) const
180 {
181#include "pqxx/internal/ignore-deprecated-pre.hxx"
182 return conn().unesc_raw(text);
183#include "pqxx/internal/ignore-deprecated-post.hxx"
184 }
185
187
190 [[nodiscard]] std::basic_string<std::byte> unesc_bin(char const text[])
191 {
192 return conn().unesc_bin(text);
193 }
194
196
197 template<typename T> [[nodiscard]] std::string quote(T const &t) const
198 {
199 return conn().quote(t);
200 }
201
202 [[deprecated(
203 "Use std::basic_string<std::byte> instead of binarystring.")]] std::string
204 quote(binarystring const &t) const
205 {
206 return conn().quote(t.bytes_view());
207 }
208
210 [[deprecated("Use quote(std::basic_string_view<std::byte>).")]] std::string
211 quote_raw(unsigned char const bin[], std::size_t len) const
212 {
213 return quote(binary_cast(bin, len));
214 }
215
217 [[deprecated("Use quote(std::basic_string_view<std::byte>).")]] std::string
218 quote_raw(zview bin) const;
219
220#if defined(PQXX_HAVE_CONCEPTS)
222
223 template<binary DATA>
224 [[nodiscard]] std::string quote_raw(DATA const &data) const
225 {
226 return conn().quote_raw(data);
227 }
228#endif
229
231 [[nodiscard]] std::string quote_name(std::string_view identifier) const
232 {
233 return conn().quote_name(identifier);
234 }
235
237 [[nodiscard]] std::string
238 esc_like(std::string_view bin, char escape_char = '\\') const
239 {
240 return conn().esc_like(bin, escape_char);
241 }
243
285
287
292 [[deprecated("The desc parameter is going away.")]] result
293 exec(std::string_view query, std::string_view desc);
294
296
300 result exec(std::string_view query)
301 {
302#include "pqxx/internal/ignore-deprecated-pre.hxx"
303 return exec(query, std::string_view{});
304#include "pqxx/internal/ignore-deprecated-post.hxx"
305 }
306
308
313 [[deprecated(
314 "Pass your query as a std::string_view, not stringstream.")]] result
315 exec(std::stringstream const &query, std::string_view desc)
316 {
317#include "pqxx/internal/ignore-deprecated-pre.hxx"
318 return exec(query.str(), desc);
319#include "pqxx/internal/ignore-deprecated-post.hxx"
320 }
321
323
328 [[deprecated("The desc parameter is going away.")]] result
329 exec0(zview query, std::string_view desc)
330 {
331#include "pqxx/internal/ignore-deprecated-pre.hxx"
332 return exec_n(0, query, desc);
333#include "pqxx/internal/ignore-deprecated-post.hxx"
334 }
335
337
343 {
344 return exec_n(0, query);
345 }
346
348
354 [[deprecated("The desc parameter is going away.")]] row
355 exec1(zview query, std::string_view desc)
356 {
357#include "pqxx/internal/ignore-deprecated-pre.hxx"
358 return exec_n(1, query, desc).front();
359#include "pqxx/internal/ignore-deprecated-post.hxx"
360 }
361
363
370 {
371 return exec_n(1, query).front();
372 }
373
375
380 [[deprecated("The desc parameter is going away.")]] result
381 exec_n(result::size_type rows, zview query, std::string_view desc);
382
384
390 {
391#include "pqxx/internal/ignore-deprecated-pre.hxx"
392 return exec_n(rows, query, std::string_view{});
393#include "pqxx/internal/ignore-deprecated-post.hxx"
394 }
395
397
400 template<typename TYPE>
401 [[deprecated("The desc parameter is going away.")]] TYPE
402 query_value(zview query, std::string_view desc)
403 {
404#include "pqxx/internal/ignore-deprecated-pre.hxx"
405 row const r{exec1(query, desc)};
406#include "pqxx/internal/ignore-deprecated-post.hxx"
407 if (std::size(r) != 1)
408 throw usage_error{internal::concat(
409 "Queried single value from result with ", std::size(r), " columns.")};
410 return r[0].as<TYPE>();
411 }
412
414
420 template<typename TYPE> TYPE query_value(zview query)
421 {
422 row const r{exec1(query)};
423 if (std::size(r) != 1)
424 throw usage_error{internal::concat(
425 "Queried single value from result with ", std::size(r), " columns.")};
426 return r[0].as<TYPE>();
427 }
428
430
437 template<typename... TYPE>
438 [[nodiscard]] std::tuple<TYPE...> query1(zview query)
439 {
440 return exec1(query).as<TYPE...>();
441 }
442
444
451 template<typename... TYPE>
452 [[nodiscard]] std::optional<std::tuple<TYPE...>> query01(zview query)
453 {
454 result res{exec(query)};
455 auto const rows{std::size(res)};
456 switch (rows)
457 {
458 case 0: return {};
459 case 1: return {res[0].as<TYPE...>()};
460 default:
461 throw unexpected_rows{internal::concat(
462 "Expected at most one row of data, got "sv, rows, "."sv)};
463 }
464 }
465
467
511 template<typename... TYPE>
512 [[nodiscard]] auto stream(std::string_view query) &
513 {
514 return pqxx::internal::stream_query<TYPE...>{*this, query};
515 }
516
517 // C++20: Concept like std::invocable, but without specifying param types.
519
543 template<typename CALLABLE>
544 auto for_stream(std::string_view query, CALLABLE &&func)
545 {
546 using param_types =
548 param_types const *const sample{nullptr};
549 auto data_stream{stream_like(query, sample)};
550 for (auto const &fields : data_stream) std::apply(func, fields);
551 }
552
553 template<typename CALLABLE>
554 [[deprecated(
555 "pqxx::transaction_base::for_each is now called for_stream.")]] auto
556 for_each(std::string_view query, CALLABLE &&func)
557 {
558 return for_stream(query, std::forward<CALLABLE>(func));
559 }
560
562
593 template<typename... TYPE> auto query(zview query)
594 {
595 return exec(query).iter<TYPE...>();
596 }
597
599
607 template<typename... TYPE> auto query_n(result::size_type rows, zview query)
608 {
609 return exec_n(rows, query).iter<TYPE...>();
610 }
611
612 // C++20: Concept like std::invocable, but without specifying param types.
614
622 template<typename CALLABLE> void for_query(zview query, CALLABLE &&func)
623 {
624 exec(query).for_each(std::forward<CALLABLE>(func));
625 }
626
657 template<typename... Args> result exec_params(zview query, Args &&...args)
658 {
659 params pp(args...);
660 return internal_exec_params(query, pp.make_c_params());
661 }
662
663 // Execute parameterised statement, expect a single-row result.
666 template<typename... Args> row exec_params1(zview query, Args &&...args)
667 {
668 return exec_params_n(1, query, std::forward<Args>(args)...).front();
669 }
670
671 // Execute parameterised statement, expect a result with zero rows.
674 template<typename... Args> result exec_params0(zview query, Args &&...args)
675 {
676 return exec_params_n(0, query, std::forward<Args>(args)...);
677 }
678
679 // Execute parameterised statement, expect exactly a given number of rows.
682 template<typename... Args>
683 result exec_params_n(std::size_t rows, zview query, Args &&...args)
684 {
685 auto const r{exec_params(query, std::forward<Args>(args)...)};
686 check_rowcount_params(rows, std::size(r));
687 return r;
688 }
690
733
735 template<typename... Args>
736 result exec_prepared(zview statement, Args &&...args)
737 {
738 params pp(args...);
739 return internal_exec_prepared(statement, pp.make_c_params());
740 }
741
743
745 template<typename... Args>
746 row exec_prepared1(zview statement, Args &&...args)
747 {
748 return exec_prepared_n(1, statement, std::forward<Args>(args)...).front();
749 }
750
752
754 template<typename... Args>
755 result exec_prepared0(zview statement, Args &&...args)
756 {
757 return exec_prepared_n(0, statement, std::forward<Args>(args)...);
758 }
759
761
764 template<typename... Args>
765 result
766 exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
767 {
768 auto const r{exec_prepared(statement, std::forward<Args>(args)...)};
769 check_rowcount_prepared(statement, rows, std::size(r));
770 return r;
771 }
772
774
780 void process_notice(char const msg[]) const
781 {
782 m_conn.process_notice(msg);
783 }
785 void process_notice(zview msg) const
786 {
787 m_conn.process_notice(msg);
788 }
790
792 [[nodiscard]] constexpr connection &conn() const noexcept
793 {
794 return m_conn;
795 }
796
798
813 [[deprecated(
814 "Set transaction-local variables using SQL SET statements.")]] void
815 set_variable(std::string_view var, std::string_view value);
816
818
821 [[deprecated("Read variables using SQL SHOW statements.")]] std::string
822 get_variable(std::string_view);
823
824 // C++20: constexpr.
826 [[nodiscard]] std::string_view name() const &noexcept
827 {
828 return m_name;
829 }
830
831protected:
833
837 connection &c, std::string_view tname,
838 std::shared_ptr<std::string> rollback_cmd) :
839 m_conn{c}, m_name{tname}, m_rollback_cmd{rollback_cmd}
840 {}
841
843
848 transaction_base(connection &c, std::string_view tname);
849
851 explicit transaction_base(connection &c);
852
854 void register_transaction();
855
857 void close() noexcept;
858
860 virtual void do_commit() = 0;
861
863
866 virtual void do_abort();
867
869 void set_rollback_cmd(std::shared_ptr<std::string> cmd)
870 {
871 m_rollback_cmd = cmd;
872 }
873
875 result direct_exec(std::string_view, std::string_view desc = ""sv);
876 result
877 direct_exec(std::shared_ptr<std::string>, std::string_view desc = ""sv);
878
879private:
880 enum class status
881 {
882 active,
883 aborted,
884 committed,
885 in_doubt
886 };
887
888 PQXX_PRIVATE void check_pending_error();
889
890 result
891 internal_exec_prepared(zview statement, internal::c_params const &args);
892
893 result internal_exec_params(zview query, internal::c_params const &args);
894
896 void check_rowcount_prepared(
897 zview statement, result::size_type expected_rows,
898 result::size_type actual_rows);
899
901 void
902 check_rowcount_params(std::size_t expected_rows, std::size_t actual_rows);
903
905 [[nodiscard]] std::string description() const;
906
907 friend class pqxx::internal::gate::transaction_transaction_focus;
908 PQXX_PRIVATE void register_focus(transaction_focus *);
909 PQXX_PRIVATE void unregister_focus(transaction_focus *) noexcept;
910 PQXX_PRIVATE void register_pending_error(zview) noexcept;
911 PQXX_PRIVATE void register_pending_error(std::string &&) noexcept;
912
914 template<typename... ARGS>
915 auto stream_like(std::string_view query, std::tuple<ARGS...> const *)
916 {
917 return stream<ARGS...>(query);
918 }
919
920 connection &m_conn;
921
923
926 transaction_focus const *m_focus = nullptr;
927
928 status m_status = status::active;
929 bool m_registered = false;
930 std::string m_name;
931 std::string m_pending_error;
932
934 std::shared_ptr<std::string> m_rollback_cmd;
935
936 static constexpr std::string_view s_type_name{"transaction"sv};
937};
938
939
940// C++20: Can borrowed_range help?
942template<>
943std::string_view transaction_base::query_value<std::string_view>(
944 zview query, std::string_view desc) = delete;
946template<>
947zview transaction_base::query_value<zview>(
948 zview query, std::string_view desc) = delete;
949
950} // namespace pqxx
951
952
953namespace pqxx::internal
954{
956template<pqxx::isolation_level isolation, pqxx::write_policy rw>
957extern const zview begin_cmd;
958
959// These are not static members, so "constexpr" does not imply "inline".
960template<>
961inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
962 "BEGIN"_zv};
963template<>
964inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
965 "BEGIN READ ONLY"_zv};
966template<>
967inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
968 "BEGIN ISOLATION LEVEL REPEATABLE READ"_zv};
969template<>
970inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
971 "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"_zv};
972template<>
973inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
974 "BEGIN ISOLATION LEVEL SERIALIZABLE"_zv};
975template<>
976inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
977 "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"_zv};
978} // namespace pqxx::internal
979
980#include "pqxx/internal/stream_query_impl.hxx"
981#endif
auto esc(ARGS &&...args) const
Escape string for use as SQL string literal in this transaction.
Definition transaction_base.hxx:131
The home of all libpqxx classes, functions, templates, etc.
Definition array.hxx:33
std::basic_string_view< std::byte > binary_cast(TYPE const &data)
Cast binary data to a type that libpqxx will recognise as binary.
Definition util.hxx:303
Internal items for libpqxx' own use. Do not use these yourself.
Definition composite.hxx:84
const zview begin_cmd
The SQL command for starting a given type of transaction.
decltype(strip_types(std::declval< TYPES... >())) strip_types_t
Take a tuple type and apply strip_t to its component types.
Definition util.hxx:527
Definition connection.hxx:109
Binary data corresponding to PostgreSQL's "BYTEA" binary-string type.
Definition binarystring.hxx:59
std::basic_string_view< std::byte > bytes_view() const
Read data as a std::basic_string_view<std::byte>.
Definition binarystring.hxx:178
Connection to a database.
Definition connection.hxx:250
Error in usage of libpqxx library, similar to std::logic_error.
Definition except.hxx:238
Query returned an unexpected number of rows.
Definition except.hxx:320
Build a parameter list for a parameterised or prepared statement.
Definition params.hxx:220
pqxx::internal::c_params make_c_params() const
For internal use: Generate a params object for use in calls.
Definition params.cxx:96
Result set containing data returned by a query or command.
Definition result.hxx:73
result_size_type size_type
Definition result.hxx:75
Reference to one row in a result.
Definition row.hxx:47
reference front() const noexcept
Definition row.cxx:60
Interface definition (and common code) for "transaction" classes.
Definition transaction_base.hxx:88
result exec_prepared(zview statement, Args &&...args)
Execute a prepared statement, with optional arguments.
Definition transaction_base.hxx:736
std::basic_string< std::byte > unesc_bin(zview text)
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:169
result exec0(zview query, std::string_view desc)
Execute command, which should return zero rows of data.
Definition transaction_base.hxx:329
constexpr connection & conn() const noexcept
The connection in which this transaction lives.
Definition transaction_base.hxx:792
auto for_each(std::string_view query, CALLABLE &&func)
Definition transaction_base.hxx:556
auto query(zview query)
Execute query, read full results, then iterate rows of data.
Definition transaction_base.hxx:593
void process_notice(zview msg) const
Have connection process a warning message.
Definition transaction_base.hxx:785
result exec0(zview query)
Execute command, which should return zero rows of data.
Definition transaction_base.hxx:342
auto query_n(result::size_type rows, zview query)
Perform query, expect given number of rows, iterate results.
Definition transaction_base.hxx:607
std::string unesc_raw(char const *text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:179
TYPE query_value(zview query, std::string_view desc)
Perform query, expecting exactly 1 row with 1 field, and convert it.
Definition transaction_base.hxx:402
result exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
Execute a prepared statement, expect a result with given number of rows.
Definition transaction_base.hxx:766
transaction_base(transaction_base const &)=delete
transaction_base(connection &c, std::string_view tname, std::shared_ptr< std::string > rollback_cmd)
Create a transaction (to be called by implementation classes only).
Definition transaction_base.hxx:836
std::string quote(T const &t) const
Represent object as SQL string, including quoting & escaping.
Definition transaction_base.hxx:197
row exec_params1(zview query, Args &&...args)
Definition transaction_base.hxx:666
TYPE query_value(zview query)
Perform query, expecting exactly 1 row with 1 field, and convert it.
Definition transaction_base.hxx:420
transaction_base & operator=(transaction_base const &)=delete
auto esc_raw(ARGS &&...args) const
Escape binary data for use as SQL string literal in this transaction.
Definition transaction_base.hxx:148
result exec(std::stringstream const &query, std::string_view desc)
Execute a command.
Definition transaction_base.hxx:315
std::string quote(binarystring const &t) const
Definition transaction_base.hxx:204
row exec1(zview query)
Execute command returning a single row of data.
Definition transaction_base.hxx:369
row exec1(zview query, std::string_view desc)
Execute command returning a single row of data.
Definition transaction_base.hxx:355
transaction_base(transaction_base &&)=delete
result exec_params(zview query, Args &&...args)
Execute an SQL statement with parameters.
Definition transaction_base.hxx:657
std::optional< std::tuple< TYPE... > > query01(zview query)
Query at most one row of data, and if there is one, convert it.
Definition transaction_base.hxx:452
result exec_params0(zview query, Args &&...args)
Definition transaction_base.hxx:674
auto for_stream(std::string_view query, CALLABLE &&func)
Perform a streaming query, and for each result row, call func.
Definition transaction_base.hxx:544
std::string unesc_raw(zview text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:158
result exec_prepared0(zview statement, Args &&...args)
Execute a prepared statement, and expect a result with zero rows.
Definition transaction_base.hxx:755
std::string esc_like(std::string_view bin, char escape_char='\\') const
Escape string for literal LIKE match.
Definition transaction_base.hxx:238
std::basic_string< std::byte > unesc_bin(char const text[])
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:190
transaction_base & operator=(transaction_base &&)=delete
result exec_n(result::size_type rows, zview query)
Execute command, expect given number of rows.
Definition transaction_base.hxx:389
std::tuple< TYPE... > query1(zview query)
Perform query returning exactly one row, and convert its fields.
Definition transaction_base.hxx:438
result exec(std::string_view query)
Execute a command.
Definition transaction_base.hxx:300
row exec_prepared1(zview statement, Args &&...args)
Execute a prepared statement, and expect a single-row result.
Definition transaction_base.hxx:746
std::string quote_name(std::string_view identifier) const
Escape an SQL identifier for use in a query.
Definition transaction_base.hxx:231
std::string quote_raw(unsigned char const bin[], std::size_t len) const
Binary-escape and quote a binary string for use as an SQL constant.
Definition transaction_base.hxx:211
std::string_view name() const &noexcept
Transaction name, if you passed one to the constructor; or empty string.
Definition transaction_base.hxx:826
result exec_params_n(std::size_t rows, zview query, Args &&...args)
Definition transaction_base.hxx:683
auto stream(std::string_view query) &
Execute a query, and loop over the results row by row.
Definition transaction_base.hxx:512
void for_query(zview query, CALLABLE &&func)
Execute a query, load the full result, and perform func for each row.
Definition transaction_base.hxx:622
void process_notice(char const msg[]) const
Have connection process a warning message.
Definition transaction_base.hxx:780
Base class for things that monopolise a transaction's attention.
Definition transaction_focus.hxx:29
Marker-type wrapper: zero-terminated std::string_view.
Definition zview.hxx:38