libpqxx 7.7.5
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/isolation.hxx"
36#include "pqxx/result.hxx"
37#include "pqxx/row.hxx"
38#include "pqxx/stream_from.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
71
76class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base
77{
78public:
79 transaction_base() = delete;
84
85 virtual ~transaction_base() = 0;
86
88
101 void commit();
102
104
107 void abort();
108
120 template<typename... ARGS> [[nodiscard]] auto esc(ARGS &&...args) const
121 {
122 return conn().esc(std::forward<ARGS>(args)...);
123 }
124
126
137 template<typename... ARGS> [[nodiscard]] auto esc_raw(ARGS &&...args) const
138 {
139 return conn().esc_raw(std::forward<ARGS>(args)...);
140 }
141
143
146 [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
147 unesc_raw(zview text) const
148 {
149#include "pqxx/internal/ignore-deprecated-pre.hxx"
150 return conn().unesc_raw(text);
151#include "pqxx/internal/ignore-deprecated-post.hxx"
152 }
153
155
158 [[nodiscard]] std::basic_string<std::byte> unesc_bin(zview text)
159 {
160 return conn().unesc_bin(text);
161 }
162
164
167 [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
168 unesc_raw(char const *text) const
169 {
170#include "pqxx/internal/ignore-deprecated-pre.hxx"
171 return conn().unesc_raw(text);
172#include "pqxx/internal/ignore-deprecated-post.hxx"
173 }
174
176
179 [[nodiscard]] std::basic_string<std::byte> unesc_bin(char const text[])
180 {
181 return conn().unesc_bin(text);
182 }
183
185
186 template<typename T> [[nodiscard]] std::string quote(T const &t) const
187 {
188 return conn().quote(t);
189 }
190
191 [[deprecated(
192 "Use std::basic_string<std::byte> instead of binarystring.")]] std::string
193 quote(binarystring const &t) const
194 {
195 return conn().quote(t.bytes_view());
196 }
197
199 [[deprecated("Use quote(std::basic_string_view<std::byte>).")]] std::string
200 quote_raw(unsigned char const bin[], std::size_t len) const
201 {
202 return quote(binary_cast(bin, len));
203 }
204
206 [[deprecated("Use quote(std::basic_string_view<std::byte>).")]] std::string
207 quote_raw(zview bin) const;
208
209#if defined(PQXX_HAVE_CONCEPTS)
211
212 template<binary DATA>
213 [[nodiscard]] std::string quote_raw(DATA const &data) const
214 {
215 return conn().quote_raw(data);
216 }
217#endif
218
220 [[nodiscard]] std::string quote_name(std::string_view identifier) const
221 {
222 return conn().quote_name(identifier);
223 }
224
226 [[nodiscard]] std::string
227 esc_like(std::string_view bin, char escape_char = '\\') const
228 {
229 return conn().esc_like(bin, escape_char);
230 }
232
273
275
280 [[deprecated("The desc parameter is going away.")]] result
281 exec(std::string_view query, std::string_view desc);
282
284
288 result exec(std::string_view query)
289 {
290#include "pqxx/internal/ignore-deprecated-pre.hxx"
291 return exec(query, std::string_view{});
292#include "pqxx/internal/ignore-deprecated-post.hxx"
293 }
294
296
301 [[deprecated(
302 "Pass your query as a std::string_view, not stringstream.")]] result
303 exec(std::stringstream const &query, std::string_view desc)
304 {
305#include "pqxx/internal/ignore-deprecated-pre.hxx"
306 return exec(query.str(), desc);
307#include "pqxx/internal/ignore-deprecated-post.hxx"
308 }
309
311
316 [[deprecated("The desc parameter is going away.")]] result
317 exec0(zview query, std::string_view desc)
318 {
319#include "pqxx/internal/ignore-deprecated-pre.hxx"
320 return exec_n(0, query, desc);
321#include "pqxx/internal/ignore-deprecated-post.hxx"
322 }
323
325
331 {
332 return exec_n(0, query);
333 }
334
336
342 [[deprecated("The desc parameter is going away.")]] row
343 exec1(zview query, std::string_view desc)
344 {
345#include "pqxx/internal/ignore-deprecated-pre.hxx"
346 return exec_n(1, query, desc).front();
347#include "pqxx/internal/ignore-deprecated-post.hxx"
348 }
349
351
358 {
359 return exec_n(1, query).front();
360 }
361
363
368 [[deprecated("The desc parameter is going away.")]] result
369 exec_n(result::size_type rows, zview query, std::string_view desc);
370
372
378 {
379#include "pqxx/internal/ignore-deprecated-pre.hxx"
380 return exec_n(rows, query, std::string_view{});
381#include "pqxx/internal/ignore-deprecated-post.hxx"
382 }
383
385
388 template<typename TYPE>
389 [[deprecated("The desc parameter is going away.")]] TYPE
390 query_value(zview query, std::string_view desc)
391 {
392#include "pqxx/internal/ignore-deprecated-pre.hxx"
393 row const r{exec1(query, desc)};
394#include "pqxx/internal/ignore-deprecated-post.hxx"
395 if (std::size(r) != 1)
396 throw usage_error{internal::concat(
397 "Queried single value from result with ", std::size(r), " columns.")};
398 return r[0].as<TYPE>();
399 }
400
402
408 template<typename TYPE> TYPE query_value(zview query)
409 {
410 row const r{exec1(query)};
411 if (std::size(r) != 1)
412 throw usage_error{internal::concat(
413 "Queried single value from result with ", std::size(r), " columns.")};
414 return r[0].as<TYPE>();
415 }
416
418
425 template<typename... TYPE>
426 [[nodiscard]] std::tuple<TYPE...> query1(zview query)
427 {
428 return exec1(query).as<TYPE...>();
429 }
430
432
439 template<typename... TYPE>
440 [[nodiscard]] std::optional<std::tuple<TYPE...>> query01(zview query)
441 {
442 result res{exec(query)};
443 auto const rows{std::size(res)};
444 switch (rows)
445 {
446 case 0: return {};
447 case 1: return {res[0].as<TYPE...>()};
448 default:
449 throw unexpected_rows{internal::concat(
450 "Expected at most one row of data, got "sv, rows, "."sv)};
451 }
452 }
453
455
501 template<typename... TYPE>
502 [[nodiscard]] auto stream(std::string_view query) &
503 {
504 // Tricky: std::make_unique() supports constructors but not RVO functions.
505 return pqxx::internal::owning_stream_input_iteration<TYPE...>{
506 std::unique_ptr<stream_from>{
507 new stream_from{stream_from::query(*this, query)}}};
508 }
509
510 // C++20: Concept like std::invocable, but without specifying param types.
512
531 template<typename CALLABLE>
532 auto for_stream(std::string_view query, CALLABLE &&func)
533 {
534 using param_types =
536 param_types const *const sample{nullptr};
537 auto data_stream{stream_like(query, sample)};
538 for (auto const &fields : data_stream) std::apply(func, fields);
539 }
540
541 template<typename CALLABLE>
542 [[deprecated(
543 "pqxx::transaction_base::for_each is now called for_stream.")]] auto
544 for_each(std::string_view query, CALLABLE &&func)
545 {
546 return for_stream(query, std::forward<CALLABLE>(func));
547 }
548
550
581 template<typename... TYPE> auto query(zview query)
582 {
583 return exec(query).iter<TYPE...>();
584 }
585
587
595 template<typename... TYPE> auto query_n(result::size_type rows, zview query)
596 {
597 return exec_n(rows, query).iter<TYPE...>();
598 }
599
600 // C++20: Concept like std::invocable, but without specifying param types.
602
610 template<typename CALLABLE> void for_query(zview query, CALLABLE &&func)
611 {
612 exec(query).for_each(std::forward<CALLABLE>(func));
613 }
614
645 template<typename... Args> result exec_params(zview query, Args &&...args)
646 {
647 params pp(args...);
648 return internal_exec_params(query, pp.make_c_params());
649 }
650
651 // Execute parameterised statement, expect a single-row result.
654 template<typename... Args> row exec_params1(zview query, Args &&...args)
655 {
656 return exec_params_n(1, query, std::forward<Args>(args)...).front();
657 }
658
659 // Execute parameterised statement, expect a result with zero rows.
662 template<typename... Args> result exec_params0(zview query, Args &&...args)
663 {
664 return exec_params_n(0, query, std::forward<Args>(args)...);
665 }
666
667 // Execute parameterised statement, expect exactly a given number of rows.
670 template<typename... Args>
671 result exec_params_n(std::size_t rows, zview query, Args &&...args)
672 {
673 auto const r{exec_params(query, std::forward<Args>(args)...)};
674 check_rowcount_params(rows, std::size(r));
675 return r;
676 }
678
710
712 template<typename... Args>
713 result exec_prepared(zview statement, Args &&...args)
714 {
715 params pp(args...);
716 return internal_exec_prepared(statement, pp.make_c_params());
717 }
718
720
722 template<typename... Args>
723 row exec_prepared1(zview statement, Args &&...args)
724 {
725 return exec_prepared_n(1, statement, std::forward<Args>(args)...).front();
726 }
727
729
731 template<typename... Args>
732 result exec_prepared0(zview statement, Args &&...args)
733 {
734 return exec_prepared_n(0, statement, std::forward<Args>(args)...);
735 }
736
738
741 template<typename... Args>
742 result
743 exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
744 {
745 auto const r{exec_prepared(statement, std::forward<Args>(args)...)};
746 check_rowcount_prepared(statement, rows, std::size(r));
747 return r;
748 }
749
751
757 void process_notice(char const msg[]) const
758 {
759 m_conn.process_notice(msg);
760 }
762 void process_notice(zview msg) const
763 {
764 m_conn.process_notice(msg);
765 }
767
769 [[nodiscard]] constexpr connection &conn() const noexcept
770 {
771 return m_conn;
772 }
773
775
790 [[deprecated(
791 "Set transaction-local variables using SQL SET statements.")]] void
792 set_variable(std::string_view var, std::string_view value);
793
795
798 [[deprecated("Read variables using SQL SHOW statements.")]] std::string
799 get_variable(std::string_view);
800
801 // C++20: constexpr.
803 [[nodiscard]] std::string_view name() const &noexcept
804 {
805 return m_name;
806 }
807
808protected:
810
814 connection &c, std::string_view tname,
815 std::shared_ptr<std::string> rollback_cmd) :
816 m_conn{c}, m_name{tname}, m_rollback_cmd{rollback_cmd}
817 {}
818
820
825 transaction_base(connection &c, std::string_view tname);
826
828 explicit transaction_base(connection &c);
829
831 void register_transaction();
832
834 void close() noexcept;
835
837 virtual void do_commit() = 0;
838
840
843 virtual void do_abort();
844
846 void set_rollback_cmd(std::shared_ptr<std::string> cmd)
847 {
848 m_rollback_cmd = cmd;
849 }
850
852 result direct_exec(std::string_view, std::string_view desc = ""sv);
853 result
854 direct_exec(std::shared_ptr<std::string>, std::string_view desc = ""sv);
855
856private:
857 enum class status
858 {
859 active,
860 aborted,
861 committed,
862 in_doubt
863 };
864
865 PQXX_PRIVATE void check_pending_error();
866
867 result
868 internal_exec_prepared(zview statement, internal::c_params const &args);
869
870 result internal_exec_params(zview query, internal::c_params const &args);
871
873 void check_rowcount_prepared(
874 zview statement, result::size_type expected_rows,
875 result::size_type actual_rows);
876
878 void
879 check_rowcount_params(std::size_t expected_rows, std::size_t actual_rows);
880
882 [[nodiscard]] std::string description() const;
883
884 friend class pqxx::internal::gate::transaction_transaction_focus;
885 PQXX_PRIVATE void register_focus(transaction_focus *);
886 PQXX_PRIVATE void unregister_focus(transaction_focus *) noexcept;
887 PQXX_PRIVATE void register_pending_error(zview) noexcept;
888 PQXX_PRIVATE void register_pending_error(std::string &&) noexcept;
889
891 template<typename... ARGS>
892 auto stream_like(std::string_view query, std::tuple<ARGS...> const *)
893 {
894 return stream<ARGS...>(query);
895 }
896
897 connection &m_conn;
898
900
903 transaction_focus const *m_focus = nullptr;
904
905 status m_status = status::active;
906 bool m_registered = false;
907 std::string m_name;
908 std::string m_pending_error;
909
911 std::shared_ptr<std::string> m_rollback_cmd;
912
913 static constexpr std::string_view s_type_name{"transaction"sv};
914};
915
916
917// C++20: Can borrowed_range help?
919template<>
920std::string_view transaction_base::query_value<std::string_view>(
921 zview query, std::string_view desc) = delete;
923template<>
924zview transaction_base::query_value<zview>(
925 zview query, std::string_view desc) = delete;
926
927} // namespace pqxx
928
929
930namespace pqxx::internal
931{
933template<pqxx::isolation_level isolation, pqxx::write_policy rw>
934extern const zview begin_cmd;
935
936// These are not static members, so "constexpr" does not imply "inline".
937template<>
938inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
939 "BEGIN"_zv};
940template<>
941inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
942 "BEGIN READ ONLY"_zv};
943template<>
944inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
945 "BEGIN ISOLATION LEVEL REPEATABLE READ"_zv};
946template<>
947inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
948 "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"_zv};
949template<>
950inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
951 "BEGIN ISOLATION LEVEL SERIALIZABLE"_zv};
952template<>
953inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
954 "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"_zv};
955} // namespace pqxx::internal
956#endif
auto esc(ARGS &&...args) const
Escape string for use as SQL string literal in this transaction.
Definition transaction_base.hxx:120
The home of all libpqxx classes, functions, templates, etc.
Definition array.hxx:27
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:306
Internal items for libpqxx' own use. Do not use these yourself.
Definition composite.hxx:83
decltype(strip_types(std::declval< TYPES... >())) strip_types_t
Take a tuple type and apply strip_t to its component types.
Definition util.hxx:529
Definition connection.hxx:99
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:185
Error in usage of libpqxx library, similar to std::logic_error.
Definition except.hxx:174
Query returned an unexpected number of rows.
Definition except.hxx:209
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:74
result_size_type size_type
Definition result.hxx:76
Reference to one row in a result.
Definition row.hxx:47
reference front() const noexcept
Definition row.cxx:60
Stream data from the database.
Definition stream_from.hxx:78
Interface definition (and common code) for "transaction" classes.
Definition transaction_base.hxx:77
result exec_prepared(zview statement, Args &&...args)
Execute a prepared statement, with optional arguments.
Definition transaction_base.hxx:713
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:158
result exec0(zview query, std::string_view desc)
Execute command, which should return zero rows of data.
Definition transaction_base.hxx:317
constexpr connection & conn() const noexcept
The connection in which this transaction lives.
Definition transaction_base.hxx:769
auto for_each(std::string_view query, CALLABLE &&func)
Definition transaction_base.hxx:544
auto query(zview query)
Execute query, read full results, then iterate rows of data.
Definition transaction_base.hxx:581
void process_notice(zview msg) const
Have connection process a warning message.
Definition transaction_base.hxx:762
result exec0(zview query)
Execute command, which should return zero rows of data.
Definition transaction_base.hxx:330
auto query_n(result::size_type rows, zview query)
Perform query, expect given number of rows, iterate results.
Definition transaction_base.hxx:595
std::string unesc_raw(char const *text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:168
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:390
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:743
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:813
std::string quote(T const &t) const
Represent object as SQL string, including quoting & escaping.
Definition transaction_base.hxx:186
row exec_params1(zview query, Args &&...args)
Definition transaction_base.hxx:654
TYPE query_value(zview query)
Perform query, expecting exactly 1 row with 1 field, and convert it.
Definition transaction_base.hxx:408
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:137
result exec(std::stringstream const &query, std::string_view desc)
Execute a command.
Definition transaction_base.hxx:303
std::string quote(binarystring const &t) const
Definition transaction_base.hxx:193
row exec1(zview query)
Execute command returning a single row of data.
Definition transaction_base.hxx:357
row exec1(zview query, std::string_view desc)
Execute command returning a single row of data.
Definition transaction_base.hxx:343
transaction_base(transaction_base &&)=delete
result exec_params(zview query, Args &&...args)
Execute an SQL statement with parameters.
Definition transaction_base.hxx:645
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:440
result exec_params0(zview query, Args &&...args)
Definition transaction_base.hxx:662
auto for_stream(std::string_view query, CALLABLE &&func)
Perform a streaming query, and for each result row, call func.
Definition transaction_base.hxx:532
std::string unesc_raw(zview text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition transaction_base.hxx:147
result exec_prepared0(zview statement, Args &&...args)
Execute a prepared statement, and expect a result with zero rows.
Definition transaction_base.hxx:732
std::string esc_like(std::string_view bin, char escape_char='\\') const
Escape string for literal LIKE match.
Definition transaction_base.hxx:227
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:179
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:377
std::tuple< TYPE... > query1(zview query)
Perform query returning exactly one row, and convert its fields.
Definition transaction_base.hxx:426
result exec(std::string_view query)
Execute a command.
Definition transaction_base.hxx:288
row exec_prepared1(zview statement, Args &&...args)
Execute a prepared statement, and expect a single-row result.
Definition transaction_base.hxx:723
std::string quote_name(std::string_view identifier) const
Escape an SQL identifier for use in a query.
Definition transaction_base.hxx:220
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:200
std::string_view name() const &noexcept
Transaction name, if you passed one to the constructor; or empty string.
Definition transaction_base.hxx:803
result exec_params_n(std::size_t rows, zview query, Args &&...args)
Definition transaction_base.hxx:671
auto stream(std::string_view query) &
Execute a query, and loop over the results row by row.
Definition transaction_base.hxx:502
void for_query(zview query, CALLABLE &&func)
Execute a query, load the full result, and perform func for each row.
Definition transaction_base.hxx:610
void process_notice(char const msg[]) const
Have connection process a warning message.
Definition transaction_base.hxx:757
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