libpqxx  7.2.1
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) 2000-2020, 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 #include "pqxx/compiler-public.hxx"
18 #include "pqxx/internal/compiler-internal-pre.hxx"
19 
20 #include <string_view>
21 
22 /* End-user programs need not include this file, unless they define their own
23  * transaction classes. This is not something the typical program should want
24  * to do.
25  *
26  * However, reading this file is worthwhile because it defines the public
27  * interface for the available transaction classes such as transaction and
28  * nontransaction.
29  */
30 
31 #include "pqxx/connection.hxx"
32 #include "pqxx/internal/encoding_group.hxx"
33 #include "pqxx/isolation.hxx"
34 #include "pqxx/result.hxx"
35 #include "pqxx/row.hxx"
36 #include "pqxx/stream_from.hxx"
37 
38 namespace pqxx::internal::gate
39 {
40 class transaction_subtransaction;
41 class transaction_sql_cursor;
42 class transaction_stream_to;
43 class transaction_transactionfocus;
44 } // namespace pqxx::internal::gate
45 
46 
47 namespace pqxx
48 {
61 
67 class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base
68  : public virtual internal::namedclass
69 {
70 public:
71  transaction_base() = delete;
72  transaction_base(transaction_base const &) = delete;
73  transaction_base &operator=(transaction_base const &) = delete;
74 
75  virtual ~transaction_base() = 0;
76 
78 
90  void commit();
91 
93 
96  void abort();
97 
102  [[nodiscard]] std::string esc(char const text[]) const
104  {
105  return conn().esc(text);
106  }
108  [[nodiscard]] std::string esc(char const text[], std::size_t maxlen) const
109  {
110  return conn().esc(text, maxlen);
111  }
113  [[nodiscard]] std::string esc(std::string const &text) const
114  {
115  return conn().esc(text);
116  }
118  [[nodiscard]] std::string esc(std::string_view text) const
119  {
120  return conn().esc(text);
121  }
122 
124 
135  [[nodiscard]] std::string
136  esc_raw(unsigned char const data[], std::size_t len) const
137  {
138  return conn().esc_raw(data, len);
139  }
141  [[nodiscard]] std::string esc_raw(std::string const &) const;
142 
144 
147  [[nodiscard]] std::string unesc_raw(std::string const &text) const
148  {
149  return conn().unesc_raw(text);
150  }
151 
153 
156  [[nodiscard]] std::string unesc_raw(char const *text) const
157  {
158  return conn().unesc_raw(text);
159  }
160 
162 
163  template<typename T>[[nodiscard]] std::string quote(T const &t) const
164  {
165  return conn().quote(t);
166  }
167 
169  [[nodiscard]] std::string
170  quote_raw(unsigned char const bin[], std::size_t len) const
171  {
172  return conn().quote_raw(bin, len);
173  }
174 
175  [[nodiscard]] std::string quote_raw(std::string const &bin) const;
176 
178  [[nodiscard]] std::string quote_name(std::string_view identifier) const
179  {
180  return conn().quote_name(identifier);
181  }
182 
184  [[nodiscard]] std::string
185  esc_like(std::string const &bin, char escape_char = '\\') const
186  {
187  return conn().esc_like(bin, escape_char);
188  }
190 
192 
206  result exec(std::string_view query, std::string const &desc = std::string{});
207 
208  result
209  exec(std::stringstream const &query, std::string const &desc = std::string{})
210  {
211  return exec(query.str(), desc);
212  }
213 
215 
220  result
221  exec0(std::string const &query, std::string const &desc = std::string{})
222  {
223  return exec_n(0, query, desc);
224  }
225 
227 
233  row exec1(std::string const &query, std::string const &desc = std::string{})
234  {
235  return exec_n(1, query, desc).front();
236  }
237 
239 
244  result exec_n(
245  result::size_type rows, std::string const &query,
246  std::string const &desc = std::string{});
247 
249  template<typename TYPE>
251  std::string const &query, std::string const &desc = std::string{})
252  {
253  row const r{exec1(query, desc)};
254  if (std::size(r) != 1)
255  throw usage_error{
256  "Queried single value from result with " + to_string(std::size(r)) +
257  " columns."};
258  return r[0].as<TYPE>();
259  }
260 
262 
302  template<typename... TYPE>[[nodiscard]] auto stream(std::string_view query)
303  {
304  return pqxx::internal::owning_stream_input_iteration<TYPE...>{
305  std::make_unique<pqxx::stream_from>(*this, from_query_t{}, query)};
306  }
307 
337  template<typename... Args>
339  result exec_params(std::string const &query, Args &&... args)
340  {
341  return internal_exec_params(
342  query, internal::params(std::forward<Args>(args)...));
343  }
344 
345  // Execute parameterised statement, expect a single-row result.
348  template<typename... Args>
349  row exec_params1(std::string const &query, Args &&... args)
350  {
351  return exec_params_n(1, query, std::forward<Args>(args)...).front();
352  }
353 
354  // Execute parameterised statement, expect a result with zero rows.
357  template<typename... Args>
358  result exec_params0(std::string const &query, Args &&... args)
359  {
360  return exec_params_n(0, query, std::forward<Args>(args)...);
361  }
362 
363  // Execute parameterised statement, expect exactly a given number of rows.
366  template<typename... Args>
367  result
368  exec_params_n(std::size_t rows, std::string const &query, Args &&... args)
369  {
370  auto const r{exec_params(query, std::forward<Args>(args)...)};
371  check_rowcount_params(rows, std::size(r));
372  return r;
373  }
375 
404 
406  template<typename... Args>
407  result exec_prepared(zview statement, Args &&... args)
408  {
409  return internal_exec_prepared(
410  statement, internal::params(std::forward<Args>(args)...));
411  }
412 
414 
416  template<typename... Args>
417  row exec_prepared1(zview statement, Args &&... args)
418  {
419  return exec_prepared_n(1, statement, std::forward<Args>(args)...).front();
420  }
421 
423 
425  template<typename... Args>
426  result exec_prepared0(zview statement, Args &&... args)
427  {
428  return exec_prepared_n(0, statement, std::forward<Args>(args)...);
429  }
430 
432 
435  template<typename... Args>
436  result
437  exec_prepared_n(result::size_type rows, zview statement, Args &&... args)
438  {
439  auto const r{exec_prepared(statement, std::forward<Args>(args)...)};
440  check_rowcount_prepared(statement, rows, std::size(r));
441  return r;
442  }
443 
445 
450  void process_notice(char const msg[]) const { m_conn.process_notice(msg); }
453  void process_notice(std::string const &msg) const
454  {
455  m_conn.process_notice(msg);
456  }
458 
460  [[nodiscard]] connection &conn() const { return m_conn; }
461 
463 
473  void set_variable(std::string_view var, std::string_view value);
474 
476 
479  std::string get_variable(std::string_view);
480 
481 protected:
483 
486  explicit transaction_base(connection &c);
487 
489  void register_transaction();
490 
492  void close() noexcept;
493 
495  virtual void do_commit() = 0;
497  virtual void do_abort() = 0;
498 
499  // For use by implementing class:
500 
502  result direct_exec(std::string_view);
503  result direct_exec(std::shared_ptr<std::string>);
504 
505 private:
506  enum class status
507  {
508  nascent,
509  active,
510  aborted,
511  committed,
512  in_doubt
513  };
514 
515  PQXX_PRIVATE void check_pending_error();
516 
517  template<typename T> bool parm_is_null(T *p) const noexcept
518  {
519  return p == nullptr;
520  }
521  template<typename T> bool parm_is_null(T) const noexcept { return false; }
522 
523  result internal_exec_prepared(zview statement, internal::params const &args);
524 
525  result
526  internal_exec_params(std::string const &query, internal::params const &args);
527 
529  void check_rowcount_prepared(
530  zview statement, result::size_type expected_rows,
531  result::size_type actual_rows);
532 
534  void
535  check_rowcount_params(std::size_t expected_rows, std::size_t actual_rows);
536 
537  friend class pqxx::internal::gate::transaction_transactionfocus;
538  PQXX_PRIVATE void register_focus(internal::transactionfocus *);
539  PQXX_PRIVATE void unregister_focus(internal::transactionfocus *) noexcept;
540  PQXX_PRIVATE void register_pending_error(std::string const &) noexcept;
541 
542  connection &m_conn;
543 
545  status m_status = status::active;
546  bool m_registered = false;
547  std::string m_pending_error;
548 };
549 
550 
551 // TODO: C++20 "Conversion remains valid after underlying result dies" concept?
553 template<>
554 std::string_view transaction_base::query_value<std::string_view>(
555  std::string const &query, std::string const &desc) = delete;
557 template<>
558 zview transaction_base::query_value<zview>(
559  std::string const &query, std::string const &desc) = delete;
560 
561 
562 } // namespace pqxx
563 
564 
565 namespace pqxx::internal
566 {
568 template<pqxx::isolation_level isolation, pqxx::write_policy rw>
569 extern const zview begin_cmd;
570 
571 // These are not static members, so "constexpr" does not imply "inline".
572 template<>
573 inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
574  "BEGIN"};
575 template<>
576 inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
577  "BEGIN READ ONLY"};
578 template<>
579 inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
580  "BEGIN ISOLATION LEVEL REPEATABLE READ"};
581 template<>
582 inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
583  "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"};
584 template<>
585 inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
586  "BEGIN ISOLATION LEVEL SERIALIZABLE"};
587 template<>
588 inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
589  "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"};
590 } // namespace pqxx::internal
591 
592 #include "pqxx/internal/compiler-internal-post.hxx"
593 #endif
result exec_prepared0(zview statement, Args &&... args)
Execute a prepared statement, and expect a result with zero rows.
Definition: transaction_base.hxx:426
const zview begin_cmd
The SQL command for starting a given type of transaction.
result exec_params(std::string const &query, Args &&... args)
Execute an SQL statement with parameters.
Definition: transaction_base.hxx:339
Private namespace for libpqxx&#39;s internal use; do not access.
Definition: composite.hxx:70
std::string esc_like(std::string const &bin, char escape_char='\\') const
Escape string for literal LIKE match.
Definition: transaction_base.hxx:185
row exec1(std::string const &query, std::string const &desc=std::string{})
Execute query returning a single row of data.
Definition: transaction_base.hxx:233
result exec_params0(std::string const &query, Args &&... args)
Definition: transaction_base.hxx:358
std::string esc(std::string const &text) const
Escape string for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:113
std::string esc(char const text[], std::size_t maxlen) const
Escape string for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:108
Marker for stream_from constructors: "stream from query.".
Definition: types.hxx:59
std::string unesc_raw(char const *text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition: transaction_base.hxx:156
reference front() const noexcept
Definition: row.cxx:54
Connection to a database.
Definition: connection.hxx:164
TYPE query_value(std::string const &query, std::string const &desc=std::string{})
Execute query, expecting exactly 1 row with 1 field.
Definition: transaction_base.hxx:250
std::string to_string(field const &value)
Convert a field to a string.
Definition: result.cxx:498
Helper base class: object descriptions for error messages and such.
Definition: util.hxx:218
result exec_prepared(zview statement, Args &&... args)
Execute a prepared statement, with optional arguments.
Definition: transaction_base.hxx:407
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:25
std::string unesc_raw(std::string const &text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition: transaction_base.hxx:147
Reference to one row in a result.
Definition: row.hxx:43
auto stream(std::string_view query)
Execute a query, and loop over the results row by row.
Definition: transaction_base.hxx:302
result_size_type size_type
Definition: result.hxx:73
result exec(std::stringstream const &query, std::string const &desc=std::string{})
Definition: transaction_base.hxx:209
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:437
std::string esc_raw(unsigned char const data[], std::size_t len) const
Escape binary data for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:136
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:170
void process_notice(std::string const &msg) const
Have connection process a warning message.
Definition: transaction_base.hxx:453
Result set containing data returned by a query or command.
Definition: result.hxx:70
row exec_prepared1(zview statement, Args &&... args)
Execute a prepared statement, and expect a single-row result.
Definition: transaction_base.hxx:417
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:37
std::string quote_name(std::string_view identifier) const
Escape an SQL identifier for use in a query.
Definition: transaction_base.hxx:178
Interface definition (and common code) for "transaction" classes.
Definition: transaction_base.hxx:67
Definition: connection.hxx:94
Error in usage of libpqxx library, similar to std::logic_error.
Definition: except.hxx:164
connection & conn() const
The connection in which this transaction lives.
Definition: transaction_base.hxx:460
result exec_params_n(std::size_t rows, std::string const &query, Args &&... args)
Definition: transaction_base.hxx:368
row exec_params1(std::string const &query, Args &&... args)
Definition: transaction_base.hxx:349
std::string esc(std::string_view text) const
Escape string for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:118
result exec0(std::string const &query, std::string const &desc=std::string{})
Execute query, which should zero rows of data.
Definition: transaction_base.hxx:221
std::string quote(T const &t) const
Represent object as SQL string, including quoting & escaping.
Definition: transaction_base.hxx:163