libpqxx 7.8.1
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
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
342 result exec0(zview query) { return exec_n(0, query); }
343
345
351 [[deprecated("The desc parameter is going away.")]] row
352 exec1(zview query, std::string_view desc)
353 {
354#include "pqxx/internal/ignore-deprecated-pre.hxx"
355 return exec_n(1, query, desc).front();
356#include "pqxx/internal/ignore-deprecated-post.hxx"
357 }
358
360
366 row exec1(zview query) { return exec_n(1, query).front(); }
367
369
374 [[deprecated("The desc parameter is going away.")]] result
375 exec_n(result::size_type rows, zview query, std::string_view desc);
376
378
384 {
385#include "pqxx/internal/ignore-deprecated-pre.hxx"
386 return exec_n(rows, query, std::string_view{});
387#include "pqxx/internal/ignore-deprecated-post.hxx"
388 }
389
391
394 template<typename TYPE>
395 [[deprecated("The desc parameter is going away.")]] TYPE
396 query_value(zview query, std::string_view desc)
397 {
398#include "pqxx/internal/ignore-deprecated-pre.hxx"
399 row const r{exec1(query, desc)};
400#include "pqxx/internal/ignore-deprecated-post.hxx"
401 if (std::size(r) != 1)
402 throw usage_error{internal::concat(
403 "Queried single value from result with ", std::size(r), " columns.")};
404 return r[0].as<TYPE>();
405 }
406
408
414 template<typename TYPE> TYPE query_value(zview query)
415 {
416 row const r{exec1(query)};
417 if (std::size(r) != 1)
418 throw usage_error{internal::concat(
419 "Queried single value from result with ", std::size(r), " columns.")};
420 return r[0].as<TYPE>();
421 }
422
424
431 template<typename... TYPE>
432 [[nodiscard]] std::tuple<TYPE...> query1(zview query)
433 {
434 return exec1(query).as<TYPE...>();
435 }
436
438
445 template<typename... TYPE>
446 [[nodiscard]] std::optional<std::tuple<TYPE...>> query01(zview query)
447 {
448 result res{exec(query)};
449 auto const rows{std::size(res)};
450 switch (rows)
451 {
452 case 0: return {};
453 case 1: return {res[0].as<TYPE...>()};
454 default:
455 throw unexpected_rows{internal::concat(
456 "Expected at most one row of data, got "sv, rows, "."sv)};
457 }
458 }
459
461
505 template<typename... TYPE>
506 [[nodiscard]] auto stream(std::string_view query) &
507 {
508 return pqxx::internal::stream_query<TYPE...>{*this, query};
509 }
510
511 // C++20: Concept like std::invocable, but without specifying param types.
513
537 template<typename CALLABLE>
538 auto for_stream(std::string_view query, CALLABLE &&func)
539 {
540 using param_types =
542 param_types const *const sample{nullptr};
543 auto data_stream{stream_like(query, sample)};
544 for (auto const &fields : data_stream) std::apply(func, fields);
545 }
546
547 template<typename CALLABLE>
548 [[deprecated(
549 "pqxx::transaction_base::for_each is now called for_stream.")]] auto
550 for_each(std::string_view query, CALLABLE &&func)
551 {
552 return for_stream(query, std::forward<CALLABLE>(func));
553 }
554
556
587 template<typename... TYPE> auto query(zview query)
588 {
589 return exec(query).iter<TYPE...>();
590 }
591
593
601 template<typename... TYPE> auto query_n(result::size_type rows, zview query)
602 {
603 return exec_n(rows, query).iter<TYPE...>();
604 }
605
606 // C++20: Concept like std::invocable, but without specifying param types.
608
616 template<typename CALLABLE> void for_query(zview query, CALLABLE &&func)
617 {
618 exec(query).for_each(std::forward<CALLABLE>(func));
619 }
620
651 template<typename... Args> result exec_params(zview query, Args &&...args)
652 {
653 params pp(args...);
654 return internal_exec_params(query, pp.make_c_params());
655 }
656
657 // Execute parameterised statement, expect a single-row result.
660 template<typename... Args> row exec_params1(zview query, Args &&...args)
661 {
662 return exec_params_n(1, query, std::forward<Args>(args)...).front();
663 }
664
665 // Execute parameterised statement, expect a result with zero rows.
668 template<typename... Args> result exec_params0(zview query, Args &&...args)
669 {
670 return exec_params_n(0, query, std::forward<Args>(args)...);
671 }
672
673 // Execute parameterised statement, expect exactly a given number of rows.
676 template<typename... Args>
677 result exec_params_n(std::size_t rows, zview query, Args &&...args)
678 {
679 auto const r{exec_params(query, std::forward<Args>(args)...)};
680 check_rowcount_params(rows, std::size(r));
681 return r;
682 }
684
727
729 template<typename... Args>
730 result exec_prepared(zview statement, Args &&...args)
731 {
732 params pp(args...);
733 return internal_exec_prepared(statement, pp.make_c_params());
734 }
735
737
739 template<typename... Args>
740 row exec_prepared1(zview statement, Args &&...args)
741 {
742 return exec_prepared_n(1, statement, std::forward<Args>(args)...).front();
743 }
744
746
748 template<typename... Args>
749 result exec_prepared0(zview statement, Args &&...args)
750 {
751 return exec_prepared_n(0, statement, std::forward<Args>(args)...);
752 }
753
755
758 template<typename... Args>
759 result
760 exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
761 {
762 auto const r{exec_prepared(statement, std::forward<Args>(args)...)};
763 check_rowcount_prepared(statement, rows, std::size(r));
764 return r;
765 }
766
768
774 void process_notice(char const msg[]) const { m_conn.process_notice(msg); }
776 void process_notice(zview msg) const { m_conn.process_notice(msg); }
778
780 [[nodiscard]] constexpr connection &conn() const noexcept { return m_conn; }
781
783
798 [[deprecated(
799 "Set transaction-local variables using SQL SET statements.")]] void
800 set_variable(std::string_view var, std::string_view value);
801
803
806 [[deprecated("Read variables using SQL SHOW statements.")]] std::string
807 get_variable(std::string_view);
808
809 // C++20: constexpr.
811 [[nodiscard]] std::string_view name() const &noexcept { return m_name; }
812
813protected:
815
819 connection &c, std::string_view tname,
820 std::shared_ptr<std::string> rollback_cmd) :
821 m_conn{c}, m_name{tname}, m_rollback_cmd{rollback_cmd}
822 {}
823
825
830 transaction_base(connection &c, std::string_view tname);
831
833 explicit transaction_base(connection &c);
834
836 void register_transaction();
837
839 void close() noexcept;
840
842 virtual void do_commit() = 0;
843
845
848 virtual void do_abort();
849
851 void set_rollback_cmd(std::shared_ptr<std::string> cmd)
852 {
853 m_rollback_cmd = cmd;
854 }
855
857 result direct_exec(std::string_view, std::string_view desc = ""sv);
858 result
859 direct_exec(std::shared_ptr<std::string>, std::string_view desc = ""sv);
860
861private:
862 enum class status
863 {
864 active,
865 aborted,
866 committed,
867 in_doubt
868 };
869
870 PQXX_PRIVATE void check_pending_error();
871
872 result
873 internal_exec_prepared(zview statement, internal::c_params const &args);
874
875 result internal_exec_params(zview query, internal::c_params const &args);
876
878 void check_rowcount_prepared(
879 zview statement, result::size_type expected_rows,
880 result::size_type actual_rows);
881
883 void
884 check_rowcount_params(std::size_t expected_rows, std::size_t actual_rows);
885
887 [[nodiscard]] std::string description() const;
888
889 friend class pqxx::internal::gate::transaction_transaction_focus;
890 PQXX_PRIVATE void register_focus(transaction_focus *);
891 PQXX_PRIVATE void unregister_focus(transaction_focus *) noexcept;
892 PQXX_PRIVATE void register_pending_error(zview) noexcept;
893 PQXX_PRIVATE void register_pending_error(std::string &&) noexcept;
894
896 template<typename... ARGS>
897 auto stream_like(std::string_view query, std::tuple<ARGS...> const *)
898 {
899 return stream<ARGS...>(query);
900 }
901
902 connection &m_conn;
903
905
908 transaction_focus const *m_focus = nullptr;
909
910 status m_status = status::active;
911 bool m_registered = false;
912 std::string m_name;
913 std::string m_pending_error;
914
916 std::shared_ptr<std::string> m_rollback_cmd;
917
918 static constexpr std::string_view s_type_name{"transaction"sv};
919};
920
921
922// C++20: Can borrowed_range help?
924template<>
925std::string_view transaction_base::query_value<std::string_view>(
926 zview query, std::string_view desc) = delete;
928template<>
929zview transaction_base::query_value<zview>(
930 zview query, std::string_view desc) = delete;
931
932} // namespace pqxx
933
934
935namespace pqxx::internal
936{
938template<pqxx::isolation_level isolation, pqxx::write_policy rw>
939extern const zview begin_cmd;
940
941// These are not static members, so "constexpr" does not imply "inline".
942template<>
943inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
944 "BEGIN"_zv};
945template<>
946inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
947 "BEGIN READ ONLY"_zv};
948template<>
949inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
950 "BEGIN ISOLATION LEVEL REPEATABLE READ"_zv};
951template<>
952inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
953 "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"_zv};
954template<>
955inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
956 "BEGIN ISOLATION LEVEL SERIALIZABLE"_zv};
957template<>
958inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
959 "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"_zv};
960} // namespace pqxx::internal
961
962#include "pqxx/internal/stream_query_impl.hxx"
963#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
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:112
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:253
Error in usage of libpqxx library, similar to std::logic_error.
Definition except.hxx:249
Query returned an unexpected number of rows.
Definition except.hxx:343
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:730
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:780
auto for_each(std::string_view query, CALLABLE &&func)
Definition transaction_base.hxx:550
auto query(zview query)
Execute query, read full results, then iterate rows of data.
Definition transaction_base.hxx:587
void process_notice(zview msg) const
Have connection process a warning message.
Definition transaction_base.hxx:776
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:601
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:396
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:760
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:818
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:660
TYPE query_value(zview query)
Perform query, expecting exactly 1 row with 1 field, and convert it.
Definition transaction_base.hxx:414
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:366
row exec1(zview query, std::string_view desc)
Execute command returning a single row of data.
Definition transaction_base.hxx:352
transaction_base(transaction_base &&)=delete
result exec_params(zview query, Args &&...args)
Execute an SQL statement with parameters.
Definition transaction_base.hxx:651
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:446
result exec_params0(zview query, Args &&...args)
Definition transaction_base.hxx:668
auto for_stream(std::string_view query, CALLABLE &&func)
Perform a streaming query, and for each result row, call func.
Definition transaction_base.hxx:538
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:749
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:383
std::tuple< TYPE... > query1(zview query)
Perform query returning exactly one row, and convert its fields.
Definition transaction_base.hxx:432
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:740
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:811
result exec_params_n(std::size_t rows, zview query, Args &&...args)
Definition transaction_base.hxx:677
auto stream(std::string_view query) &
Execute a query, and loop over the results row by row.
Definition transaction_base.hxx:506
void for_query(zview query, CALLABLE &&func)
Execute a query, load the full result, and perform func for each row.
Definition transaction_base.hxx:616
void process_notice(char const msg[]) const
Have connection process a warning message.
Definition transaction_base.hxx:774
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