The home of all libpqxx classes, functions, templates, etc. More...

Namespaces
	internal
	Internal items for libpqxx' own use. Do not use these yourself.

	prepare

Classes
class	array
	An SQL array received from the database. More...

class	array_parser
	Low-level array parser. More...

class	binarystring
	Binary data corresponding to PostgreSQL's "BYTEA" binary-string type. More...

struct	nullness< binarystring >

struct	string_traits< binarystring >
	String conversion traits for `binarystring`. More...

class	blob

class	connection
	Connection to a database. More...

class	connecting
	An ongoing, non-blocking stepping stone to a connection. More...

class	cursor_base
	Common definitions for cursor types. More...

class	stateless_cursor
	"Stateless cursor" class: easy API for retrieving parts of result sets More...

class	icursorstream
	Simple read-only cursor represented as a stream of results. More...

class	icursor_iterator
	Approximate istream_iterator for icursorstream. More...

class	dbtransaction
	Abstract transaction base class: bracket transactions on the database. More...

class	errorhandler
	Base class for error-handler callbacks. More...

class	quiet_errorhandler
	An error handler that suppresses any previously registered error handlers. More...

struct	failure
	Run-time failure encountered by libpqxx, similar to std::runtime_error. More...

struct	broken_connection
	Exception class for lost or failed backend connection. More...

struct	protocol_violation
	Exception class for micommunication with the server. More...

struct	variable_set_to_null
	The caller attempted to set a variable to null, which is not allowed. More...

class	sql_error
	Exception class for failed queries. More...

struct	in_doubt_error
	"Help, I don't know whether transaction was committed successfully!" More...

struct	transaction_rollback
	The backend saw itself forced to roll back the ongoing transaction. More...

struct	serialization_failure
	Transaction failed to serialize. Please retry it. More...

struct	statement_completion_unknown
	We can't tell whether our last statement succeeded. More...

struct	deadlock_detected
	The ongoing transaction has deadlocked. Retrying it may help. More...

struct	internal_error
	Internal error in libpqxx library. More...

struct	usage_error
	Error in usage of libpqxx library, similar to std::logic_error. More...

struct	argument_error
	Invalid argument passed to libpqxx, similar to std::invalid_argument. More...

struct	conversion_error
	Value conversion failed, e.g. when converting "Hello" to int. More...

struct	unexpected_null
	Could not convert null value: target type does not support null. More...

struct	conversion_overrun
	Could not convert value to string: not enough buffer space. More...

struct	range_error
	Something is out of range, similar to std::out_of_range. More...

struct	unexpected_rows
	Query returned an unexpected number of rows. More...

struct	feature_not_supported
	Database feature not supported in current setup. More...

struct	data_exception
	Error in data provided to SQL statement. More...

struct	integrity_constraint_violation

struct	restrict_violation

struct	not_null_violation

struct	foreign_key_violation

struct	unique_violation

struct	check_violation

struct	invalid_cursor_state

struct	invalid_sql_statement_name

struct	invalid_cursor_name

struct	syntax_error

struct	undefined_column

struct	undefined_function

struct	undefined_table

struct	insufficient_privilege

struct	insufficient_resources
	Resource shortage on the server. More...

struct	disk_full

struct	out_of_memory

struct	too_many_connections

struct	plpgsql_error
	PL/pgSQL error. More...

struct	plpgsql_raise
	Exception raised in PL/pgSQL procedure. More...

struct	plpgsql_no_data_found

struct	plpgsql_too_many_rows

class	field
	Reference to a field in a result set. More...

class	field_streambuf

class	basic_fieldstream
	Input stream that gets its data from a result field. More...

class	largeobject
	Identity of a large object. More...

class	largeobjectaccess
	Accessor for large object's contents. More...

class	largeobject_streambuf
	Streambuf to use large objects in standard I/O streams. More...

class	basic_ilostream
	Input stream that gets its data from a large object. More...

class	basic_olostream
	Output stream that writes data back to a large object. More...

class	basic_lostream
	Stream that reads and writes a large object. More...

class	nontransaction
	Simple "transaction" class offering no transactional integrity. More...

class	notification_receiver

class	params
	Build a parameter list for a parameterised or prepared statement. More...

class	placeholders
	Generate parameter placeholders for use in an SQL statement. More...

class	pipeline
	Processes several queries in FIFO manner, optimized for high throughput. More...

struct	no_bound
	An unlimited boundary value to a pqxx::range. More...

class	inclusive_bound
	An inclusive boundary value to a pqxx::range. More...

class	exclusive_bound
	An exclusive boundary value to a pqxx::range. More...

class	range_bound
	A range boundary value. More...

class	range
	A C++ equivalent to PostgreSQL's range types. More...

struct	string_traits< range< TYPE > >
	String conversions for a range type. More...

struct	nullness< range< TYPE > >
	A range type does not have an innate null value. More...

class	result
	Result set containing data returned by a query or command. More...

class	robusttransaction
	Slightly slower, better-fortified version of transaction. More...

class	row
	Reference to one row in a result. More...

class	const_row_iterator
	Iterator for fields in a row. Use as row::const_iterator. More...

class	const_reverse_row_iterator
	Reverse iterator for a row. Use as row::const_reverse_iterator. More...

struct	nullness
	Traits describing a type's "null value," if any. More...

struct	no_null
	Nullness traits describing a type which does not have a null value. More...

struct	string_traits
	Traits class for use in string conversions. More...

struct	forbidden_conversion
	String traits for a forbidden type conversion. More...

struct	string_traits< char >
	You cannot convert a `char` to/from SQL. More...

struct	string_traits< unsigned char >
	You cannot convert an `unsigned char` to/from SQL. More...

struct	string_traits< signed char >
	You cannot convert a `signed char` to/from SQL. More...

struct	string_traits< std::byte >
	You cannot convert a `std::byte` to/from SQL. More...

struct	nullness< ENUM, std::enable_if_t< std::is_enum_v< ENUM > > >
	Nullness: Enums do not have an inherent null value. More...

class	stream_from
	Stream data from the database. More...

class	stream_to
	Efficiently write data directly to a database table. More...

class	subtransaction
	"Transaction" nested within another transaction More...

class	transaction
	Standard back-end transaction, templatised on isolation level. More...

class	transaction_base
	Interface definition (and common code) for "transaction" classes. More...

class	transaction_focus
	Base class for things that monopolise a transaction's attention. More...

struct	from_table_t
	Marker for stream_from constructors: "stream from table.". More...

struct	from_query_t
	Marker for stream_from constructors: "stream from query.". More...

struct	thread_safety_model
	Descriptor of library's thread-safety model. More...

struct	byte_char_traits
	Custom `std::char_trast` if the compiler does not provide one. More...

struct	has_generic_char_traits

struct	has_generic_char_traits< TYPE, std::void_t< decltype(std::char_traits< TYPE >::eof)> >

class	zview
	Marker-type wrapper: zero-terminated `std::string_view`. More...

Typedefs
using	table_path = std::initializer_list< std::string_view >
	Representation of a PostgreSQL table path. More...

using	connection_base = connection

using	fieldstream = basic_fieldstream< char >

using	ilostream = basic_ilostream< char >

using	olostream = basic_olostream< char >

using	lostream = basic_lostream< char >

using	work = transaction<>
	The default transaction type. More...

using	read_transaction = transaction< isolation_level::read_committed, write_policy::read_only >
	Read-only transaction. More...

using	result_size_type = int
	Number of rows in a result set. More...

using	result_difference_type = int
	Difference between result sizes. More...

using	row_size_type = int
	Number of fields in a row of database data. More...

using	row_difference_type = int
	Difference between row sizes. More...

using	field_size_type = std::size_t
	Number of bytes in a field of database data. More...

using	large_object_size_type = int64_t
	Number of bytes in a large object. More...

template<typename TYPE >
using	strip_t = std::remove_cv_t< std::remove_reference_t< TYPE > >
	Remove any constness, volatile, and reference-ness from a type. More...

template<typename CONTAINER >
using	value_type = strip_t< decltype(*std::begin(std::declval< CONTAINER >()))>
	The type of a container's elements. More...

using	bytes = std::conditional< has_generic_bytes_char_traits, std::basic_string< std::byte >, std::basic_string< std::byte, byte_char_traits > >::type
	Type alias for a container containing bytes. More...

using	bytes_view = std::conditional< has_generic_bytes_char_traits, std::basic_string_view< std::byte >, std::basic_string_view< std::byte, byte_char_traits > >::type
	Type alias for a view of bytes. More...

Enumerations
enum	skip_init : int { nothing , openssl , crypto }
	Flags for skipping initialisation of SSL-related libraries. More...

enum class	error_verbosity : int { terse = 0 , normal = 1 , verbose = 2 }
	Error verbosity levels. More...

enum class	write_policy { read_only , read_write }
	Should a transaction be read-only, or read-write? More...

enum	isolation_level { read_committed , repeatable_read , serializable }
	Transaction isolation levels. More...

enum class	format : int { text = 0 , binary = 1 }
	Format code: is data text or binary? More...

Functions
template<typename... T>
void	parse_composite (pqxx::internal::encoding_group enc, std::string_view text, T &...fields)
	Parse a string representation of a value of a composite type. More...

template<typename... T>
void	parse_composite (std::string_view text, T &...fields)
	Parse a string representation of a value of a composite type. More...

template<typename... T>
std::size_t	composite_size_buffer (T const &...fields) noexcept
	Estimate the buffer size needed to represent a value of a composite type. More...

template<typename... T>
char *	composite_into_buf (char begin, char end, T const &...fields)
	Render a series of values as a single composite SQL value. More...

template<skip_init... SKIP>
void	skip_init_ssl () noexcept
	Control initialisation of OpenSSL and libcrypto libraries. More...

std::string	encrypt_password (char const user[], char const password[])
	Encrypt a password. More...

std::string	encrypt_password (zview user, zview password)
	Encrypt password. More...

template<>
bool	field::to< std::string > (std::string &obj) const

template<>
bool	field::to< std::string > (std::string &obj, std::string const &default_value) const

template<>
bool	field::to< std::string_view > (std::string_view &obj) const

template<>
bool	field::to< std::string_view > (std::string_view &obj, std::string_view const &default_value) const

template<>
std::string_view	field::as< std::string_view > () const

template<>
std::string_view	field::as< std::string_view > (std::string_view const &default_value) const

template<typename CHAR >
std::basic_ostream< CHAR > &	operator<< (std::basic_ostream< CHAR > &s, field const &value)
	Write a result field to any type of stream. More...

template<typename T >
T	from_string (field const &value)
	Convert a field's value to type `T`. More...

template<>
std::nullptr_t	from_string< std::nullptr_t > (field const &value)
	Convert a field's value to `nullptr_t`. More...

template<>
std::string	to_string (field const &value)
	Convert a field to a string. More...

const_row_iterator	operator+ (const_row_iterator::difference_type o, const_row_iterator const &i) noexcept

template<typename ITER , typename ACCESS >
std::string	separated_list (std::string_view sep, ITER begin, ITER end, ACCESS access)
	Represent sequence of values as a string, joined by a given separator. More...

template<typename ITER >
std::string	separated_list (std::string_view sep, ITER begin, ITER end)
	Render sequence as a string, using given separator between items. More...

template<typename CONTAINER >
auto	separated_list (std::string_view sep, CONTAINER const &c) -> typename std::enable_if<(not std::is_void< decltype(std::begin(c))>::value and not std::is_void< decltype(std::end(c))>::value), std::string >::type
	Render items in a container as a string, using given separator. More...

template<typename TUPLE , std::size_t INDEX = 0, typename ACCESS , typename std::enable_if<(INDEX==std::tuple_size< TUPLE >::value - 1), int >::type = 0>
std::string	separated_list (std::string_view, TUPLE const &t, ACCESS const &access)
	Render items in a tuple as a string, using given separator. More...

template<typename TUPLE , std::size_t INDEX = 0, typename std::enable_if<(INDEX<=std::tuple_size< TUPLE >::value), int >::type = 0>
std::string	separated_list (std::string_view sep, TUPLE const &t)

template<typename TYPE >
void	oops_forbidden_conversion () noexcept
	Nonexistent function to indicate a disallowed type conversion. More...

template<typename TYPE >
TYPE	from_string (std::string_view text)
	Parse a value in postgres' text format as a TYPE. More...

template<>
std::string_view	from_string (std::string_view text)
	"Convert" a std::string_view to a std::string_view. More...

template<typename T >
void	from_string (std::string_view text, T &value)
	Attempt to convert postgres-generated string to given built-in object. More...

template<typename TYPE >
std::string	to_string (TYPE const &value)
	Convert a value to a readable string that PostgreSQL will understand. More...

template<typename... TYPE>
std::vector< std::string_view >	to_buf (char here, char const end, TYPE... value)
	Convert multiple values to strings inside a single buffer. More...

template<typename TYPE >
void	into_string (TYPE const &value, std::string &out)
	Convert a value to a readable string that PostgreSQL will understand. More...

template<typename TYPE >
constexpr bool	is_null (TYPE const &value) noexcept
	Is `value` null? More...

template<typename... TYPE>
std::size_t	size_buffer (TYPE const &...value) noexcept
	Estimate how much buffer space is needed to represent values as a string. More...

template<typename TYPE >
constexpr format	param_format (TYPE const &)
	What's the preferred format for passing non-null parameters of this type? More...

template<typename TYPE >
zview	generic_to_buf (char begin, char end, TYPE const &value)
	Implement `string_traits<TYPE>::to_buf` by calling `into_buf`. More...

template<>
std::string_view	transaction_base::query_value< std::string_view > (zview query, std::string_view desc)=delete
	Forbidden specialisation: underlying buffer immediately goes out of scope. More...

template<typename TRANSACTION_CALLBACK >
auto	perform (TRANSACTION_CALLBACK &&callback, int attempts=3) -> std::invoke_result_t< TRANSACTION_CALLBACK >
	Simple way to execute a transaction with automatic retry. More...

template<typename... T>
constexpr void	ignore_unused (T &&...) noexcept
	Suppress compiler warning about an unused item. More...

template<typename TO , typename FROM >
TO	check_cast (FROM value, std::string_view description)
	Cast a numeric value to another type, or throw if it underflows/overflows. More...

void	check_version () noexcept

thread_safety_model	describe_thread_safety ()
	Describe thread safety available in this build. More...

template<PQXX_POTENTIAL_BINARY_ARG TYPE>
bytes_view	binary_cast (TYPE const &data)
	Cast binary data to a type that libpqxx will recognise as binary. More...

template<PQXX_CHAR_SIZED_ARG CHAR, typename SIZE >
bytes_view	binary_cast (CHAR const *data, SIZE size)
	Construct a type that libpqxx will recognise as binary. More...

constexpr zview	operator""_zv (char const str[], std::size_t len) noexcept
	Support zview literals. More...

	PQXX_DECLARE_ENUM_CONVERSION (ExecStatusType)

Variables
template<typename TYPE >
std::string const	type_name {internal::demangle_type_name(typeid(TYPE).name())}
	A human-readable name for a type, used in error messages and such. More...

template<typename TYPE >
constexpr bool	is_sql_array {false}
	Does this type translate to an SQL array? More...

template<typename TYPE >
constexpr bool	is_unquoted_safe {false}
	Can we use this type in arrays and composite types without quoting them? More...

template<typename T >
constexpr char	array_separator {','}
	Element separator between SQL array elements of this type. More...

constexpr from_table_t	from_table
	Pass this to a `stream_from` constructor to stream table contents. More...

constexpr from_query_t	from_query
	Pass this to a `stream_from` constructor to stream query results. More...

constexpr bool	has_generic_bytes_char_traits

constexpr oid	oid_none {0}
	The "null" oid. More...

Detailed Description

The home of all libpqxx classes, functions, templates, etc.

Transaction focus: types which monopolise a transaction's attention.

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.

Handling of SQL arrays.

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.

Implementation of the pqxx::result class and support classes.

pqxx::result represents the set of result rows from a database query

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.

Typedef Documentation

◆ bytes

using pqxx::bytes = typedef std::conditional< has_generic_bytes_char_traits, std::basic_string<std::byte>, std::basic_string<std::byte, byte_char_traits> >::type

Type alias for a container containing bytes.

◆ bytes_view

using pqxx::bytes_view = typedef std::conditional< has_generic_bytes_char_traits, std::basic_string_view<std::byte>, std::basic_string_view<std::byte, byte_char_traits> >::type

Type alias for a view of bytes.

◆ connection_base

using pqxx::connection_base = typedef connection

Deprecated:: Old base class for connection. They are now the same class.

◆ field_size_type

using pqxx::field_size_type = typedef std::size_t

Number of bytes in a field of database data.

◆ fieldstream

using pqxx::fieldstream = typedef basic_fieldstream<char>

Deprecated:: Read a field using field::as<...>() or field::c_str().

◆ ilostream

using pqxx::ilostream = typedef basic_ilostream<char>

◆ large_object_size_type

using pqxx::large_object_size_type = typedef int64_t

Number of bytes in a large object.

◆ lostream

using pqxx::lostream = typedef basic_lostream<char>

◆ olostream

using pqxx::olostream = typedef basic_olostream<char>

◆ read_transaction

using pqxx::read_transaction = typedef transaction<isolation_level::read_committed, write_policy::read_only>

Read-only transaction.

◆ result_difference_type

using pqxx::result_difference_type = typedef int

Difference between result sizes.

◆ result_size_type

using pqxx::result_size_type = typedef int

Number of rows in a result set.

◆ row_difference_type

using pqxx::row_difference_type = typedef int

Difference between row sizes.

◆ row_size_type

using pqxx::row_size_type = typedef int

Number of fields in a row of database data.

◆ strip_t

template<typename TYPE >

using pqxx::strip_t = typedef std::remove_cv_t<std::remove_reference_t<TYPE> >

Remove any constness, volatile, and reference-ness from a type.

Deprecated:: In C++20 we'll replace this with std::remove_cvref.

◆ table_path

using pqxx::table_path = typedef std::initializer_list<std::string_view>

Representation of a PostgreSQL table path.

A "table path" consists of a table name, optionally prefixed by a schema name, which in turn is optionally prefixed by a database name.

A minimal example of a table path would be {mytable}. But a table path may also take the forms {myschema,mytable} or {mydb,myschema,mytable}.

◆ value_type

template<typename CONTAINER >

using pqxx::value_type = typedef strip_t<decltype(*std::begin(std::declval<CONTAINER>()))>

The type of a container's elements.

At the time of writing there's a similar thing in std::experimental, which we may or may not end up using for this.

◆ work

using pqxx::work = typedef transaction<>

The default transaction type.

Enumeration Type Documentation

◆ error_verbosity

enum pqxx::error_verbosity : int

strong

Error verbosity levels.

Enumerator
terse
normal
verbose

◆ format

enum pqxx::format : int

strong

Format code: is data text or binary?

Binary-compatible with libpq's format codes.

Enumerator
text
binary

◆ isolation_level

enum pqxx::isolation_level

Transaction isolation levels.

These are as defined in the SQL standard. But there are a few notes specific to PostgreSQL.

First, postgres does not support "read uncommitted." The lowest level you can get is "read committed," which is better. PostgreSQL is built on the MVCC paradigm, which guarantees "read committed" isolation without any additional performance overhead, so there was no point in providing the lower level.

Second, "repeatable read" also makes more isolation guarantees than the standard requires. According to the standard, this level prevents "dirty reads" and "nonrepeatable reads," but not "phantom reads." In postgres, it actually prevents all three.

Third, "serializable" is only properly supported starting at postgres 9.1. If you request "serializable" isolation on an older backend, you will get the same isolation as in "repeatable read." It's better than the "repeatable read" defined in the SQL standard, but not a complete implementation of the standard's "serializable" isolation level.

In general, a lower isolation level will allow more surprising interactions between ongoing transactions, but improve performance. A higher level gives you more protection from subtle concurrency bugs, but sometimes it may not be possible to complete your transaction without avoiding paradoxes in the data. In that case a transaction may fail, and the application will have to re-do the whole thing based on the latest state of the database. (If you want to retry your code in that situation, have a look at the transactor framework.)

Study the levels and design your application with the right level in mind.

Enumerator
read_committed
repeatable_read
serializable

◆ skip_init

enum pqxx::skip_init : int

Flags for skipping initialisation of SSL-related libraries.

When a running process makes its first SSL connection to a database through libpqxx, libpq automatically initialises the OpenSSL and libcrypto libraries. But there are scenarios in which you may want to suppress that.

This enum is a way to express this. Pass values of this enum to pqxx::skip_init_ssl as template arguments.

Enumerator
nothing	A do-nothing flag that does not affect anything.
openssl	Skip initialisation of OpenSSL library.
crypto	Skip initialisation of libcrypto.

◆ write_policy

enum pqxx::write_policy

strong

Should a transaction be read-only, or read-write?

No, this is not an isolation level. So it really doesn't belong here. But it's not really worth a separate header.

Enumerator
read_only
read_write

Function Documentation

◆ binary_cast() [1/2]

template<PQXX_CHAR_SIZED_ARG CHAR, typename SIZE >

bytes_view pqxx::binary_cast	(	CHAR const *	data,
		SIZE	size
	)

Construct a type that libpqxx will recognise as binary.

Takes a data pointer and a size, without being too strict about their types, and constructs a pqxx::bytes_view pointing to the same data.

This makes it a little easier to turn binary data, in whatever form you happen to have it, into binary data as libpqxx understands it.

◆ binary_cast() [2/2]

template<PQXX_POTENTIAL_BINARY_ARG TYPE>

bytes_view pqxx::binary_cast ( TYPE const & data )

Cast binary data to a type that libpqxx will recognise as binary.

There are many different formats for storing binary data in memory. You may have yours as a std::string, or a std::vector<uchar_t>, or one of many other types.

But for libpqxx to recognise your data as binary, it needs to be a pqxx::bytes, or a pqxx::bytes_view; or in C++20 or better, any contiguous block of std::byte.

Use binary_cast as a convenience helper to cast your data as a pqxx::bytes_view.

Warning: There are two things you should be aware of! First, the data must be contiguous in memory. In C++20 the compiler will enforce this, but in C++17 it's your own problem. Second, you must keep the object where you store the actual data alive for as long as you might use this function's return value.

Referenced by pqxx::connection::esc_raw(), pqxx::string_traits< binarystring >::into_buf(), pqxx::connection::quote_raw(), and pqxx::transaction_base::quote_raw().

◆ check_cast()

template<typename TO , typename FROM >

TO pqxx::check_cast	(	FROM	value,
		std::string_view	description
	)

Cast a numeric value to another type, or throw if it underflows/overflows.

Both types must be arithmetic types, and they must either be both integral or both floating-point types.

References pqxx::internal::cat2(), pqxx::internal::cmp_greater(), and ignore_unused().

◆ check_version()

void pqxx::check_version ( )

noexcept

Check library version at link time.

Ensures a failure when linking an application against a radically different libpqxx version than the one against which it was compiled.

Sometimes application builds fail in unclear ways because they compile using headers from libpqxx version X, but then link against libpqxx binary version Y. A typical scenario would be one where you're building against a libpqxx which you have built yourself, but a different version is installed on the system.

The check_library_version template is declared for any library version, but only actually defined for the version of the libpqxx binary against which the code is linked.

If the library binary is a different version than the one declared in these headers, then this call will fail to link: there will be no definition for the function with these exact template parameter values. There will be a definition, but the version in the parameter values will be different.

References ignore_unused(), and pqxx::internal::PQXX_VERSION_CHECK().

Referenced by pqxx::connection::connection().

◆ composite_into_buf()

template<typename... T>

char* pqxx::composite_into_buf	(	char *	begin,
		char *	end,
		T const &...	fields
	)

Render a series of values as a single composite SQL value.

Warning: This code is still experimental. Use with care.

You may use this as a helper while implementing your own string_traits for a composite type.

References composite_size_buffer().

◆ composite_size_buffer()

template<typename... T>

std::size_t pqxx::composite_size_buffer ( T const &... fields )

noexcept

Estimate the buffer size needed to represent a value of a composite type.

Returns a conservative estimate.

References pqxx::internal::empty_composite_str.

Referenced by composite_into_buf().

◆ describe_thread_safety()

pqxx::thread_safety_model PQXX_COLD pqxx::describe_thread_safety ( )

Describe thread safety available in this build.

References pqxx::thread_safety_model::description, pqxx::thread_safety_model::safe_kerberos, and pqxx::thread_safety_model::safe_libpq.

◆ encrypt_password() [1/2]

std::string PQXX_COLD pqxx::encrypt_password	(	char const	user[],
		char const	password[]
	)

Encrypt a password.

Deprecated:: Use connection::encrypt_password instead.

References pqxx::internal::pq::pqfreemem().

Referenced by encrypt_password(), and pqxx::connection::encrypt_password().

◆ encrypt_password() [2/2]

std::string pqxx::encrypt_password	(	zview	user,
		zview	password
	)

Encrypt password.

Deprecated:: Use connection::encrypt_password instead.

References pqxx::zview::c_str(), and encrypt_password().

◆ field::as< std::string_view >() [1/2]

template<>

std::string_view pqxx::field::as< std::string_view > ( ) const

References is_null(), and pqxx::internal::throw_null_conversion().

◆ field::as< std::string_view >() [2/2]

template<>

std::string_view pqxx::field::as< std::string_view > ( std::string_view const & default_value ) const

References is_null().

◆ field::to< std::string >() [1/2]

template<>

bool pqxx::field::to< std::string > ( std::string & obj ) const

References is_null().

◆ field::to< std::string >() [2/2]

template<>

bool pqxx::field::to< std::string >	(	std::string &	obj,
		std::string const &	default_value
	)		const

References is_null().

◆ field::to< std::string_view >() [1/2]

template<>

bool pqxx::field::to< std::string_view > ( std::string_view & obj ) const

References is_null().

◆ field::to< std::string_view >() [2/2]

template<>

bool pqxx::field::to< std::string_view >	(	std::string_view &	obj,
		std::string_view const &	default_value
	)		const

References is_null().

◆ from_string() [1/4]

template<typename T >

T pqxx::from_string ( field const & value )

Convert a field's value to type T.

Unlike the "regular" from_string, this knows how to deal with null values.

References pqxx::field::is_null(), pqxx::nullness< TYPE, ENABLE >::null(), pqxx::internal::throw_null_conversion(), and pqxx::field::view().

Referenced by pqxx::field::to().

◆ from_string() [2/4]

template<typename TYPE >

TYPE pqxx::from_string ( std::string_view text )

Parse a value in postgres' text format as a TYPE.

If the form of the value found in the string does not match the expected type, e.g. if a decimal point is found when converting to an integer type, the conversion fails. Overflows (e.g. converting "9999999999" to a 16-bit C++ type) are also treated as errors. If in some cases this behaviour should be inappropriate, convert to something bigger such as long int first and then truncate the resulting value.

Only the simplest possible conversions are supported. Fancy features like hexadecimal or octal, spurious signs, or exponent notation won't work. Whitespace is not stripped away. Only the kinds of strings that come out of PostgreSQL and out of to_string() can be converted.

References pqxx::string_traits< TYPE >::from_string(), and text.

◆ from_string() [3/4]

template<>

std::string_view pqxx::from_string ( std::string_view text )

"Convert" a std::string_view to a std::string_view.

Just returns its input.

Warning: Of course the result is only valid for as long as the original string remains valid! Never access the string referenced by the return value after the original has been destroyed.

References text.

◆ from_string() [4/4]

template<typename T >

void pqxx::from_string	(	std::string_view	text,
		T &	value
	)

Attempt to convert postgres-generated string to given built-in object.

This is like the single-argument form of the function, except instead of returning the value, it sets value.

You may find this more convenient in that it infers the type you want from the argument you pass. But there are disadvantages: it requires an assignment operator, and it may be less efficient.

References text.

◆ from_string< std::nullptr_t >()

template<>

std::nullptr_t pqxx::from_string< std::nullptr_t > ( field const & value )

Convert a field's value to nullptr_t.

Yes, you read that right. This conversion does nothing useful. It always returns nullptr.

Except... what if the field is not null? In that case, this throws conversion_error.

References pqxx::field::is_null().

◆ generic_to_buf()

template<typename TYPE >

zview pqxx::generic_to_buf	(	char *	begin,
		char *	end,
		TYPE const &	value
	)

Implement string_traits<TYPE>::to_buf by calling into_buf.

When you specialise string_traits for a new type, most of the time its to_buf implementation has no special optimisation tricks and just writes its text into the buffer it receives from the caller, starting at the beginning.

In that common situation, you can implement to_buf as just a call to generic_to_buf. It will call into_buf and return the right result for to_buf.

References is_null().

Referenced by pqxx::string_traits< binarystring >::to_buf(), and pqxx::string_traits< range< TYPE > >::to_buf().

◆ ignore_unused()

template<typename... T>

constexpr void pqxx::ignore_unused ( T && ... )

constexprnoexcept

Suppress compiler warning about an unused item.

Referenced by pqxx::params::append(), check_cast(), check_version(), pqxx::stream_from::complete(), and pqxx::internal::error_string().

◆ into_string()

template<typename TYPE >

void pqxx::into_string	(	TYPE const &	value,
		std::string &	out
	)

Convert a value to a readable string that PostgreSQL will understand.

This variant of to_string can sometimes save a bit of time in loops, by re-using a std::string for multiple conversions.

◆ is_null()

template<typename TYPE >

constexpr bool pqxx::is_null ( TYPE const & value )

constexprnoexcept

Is value null?

Referenced by pqxx::params::append(), pqxx::field::as(), pqxx::field::composite_to(), pqxx::exclusive_bound< TYPE >::exclusive_bound(), field::as< std::string_view >(), field::to< std::string >(), field::to< std::string_view >(), generic_to_buf(), pqxx::inclusive_bound< TYPE >::inclusive_bound(), pqxx::field::operator==(), pqxx::connection::quote(), and pqxx::field::to().

◆ oops_forbidden_conversion()

template<typename TYPE >

void pqxx::oops_forbidden_conversion ( )

noexcept

Nonexistent function to indicate a disallowed type conversion.

There is no implementation for this function, so any reference to it will fail to link. The error message will mention the function name and its template argument, as a deliberate message to an application developer that their code is attempting to use a deliberately unsupported conversion.

There are some C++ types that you may want to convert to or from SQL values, but which libpqxx deliberately does not support. Take char for example: we define no conversions for that type because it is not inherently clear whether whether the corresponding SQL type should be a single-character string, a small integer, a raw byte value, etc. The intention could differ from one call site to the next.

If an application attempts to convert these types, we try to make sure that the compiler will issue an error involving this function name, and mention the type, as a hint as to the reason.

◆ operator""_zv()

constexpr zview pqxx::operator""_zv	(	char const	str[],
		std::size_t	len
	)

constexprnoexcept

Support zview literals.

You can "import" this selectively into your namespace, without pulling in all of the pqxx namespace:

using pqxx::operator"" _zv;

◆ operator+()

const_row_iterator pqxx::operator+	(	const_row_iterator::difference_type	o,
		const_row_iterator const &	i
	)

noexcept

◆ operator<<()

template<typename CHAR >

std:: basic_ostream<CHAR>& pqxx::operator<<	(	std::basic_ostream< CHAR > &	s,
		field const &	value
	)

Write a result field to any type of stream.

Deprecated:: The C++ streams library is not great to work with. In particular, error handling is easy to get wrong. So you're probably better off doing this by hand.

This can be convenient when writing a field to an output stream. More importantly, it lets you write a field to e.g. a stringstream which you can then use to read, format and convert the field in ways that to() does not support.

Example: parse a field into a variable of the nonstandard "<tt>long long</tt>" type.

extern result R;
long long L;
stringstream S;
 
// Write field's string into S
S << R[0][0];
 
// Parse contents of S into L
S >> L;

◆ param_format()

template<typename TYPE >

constexpr format pqxx::param_format ( TYPE const & )

constexpr

What's the preferred format for passing non-null parameters of this type?

This affects how we pass parameters of TYPE when calling parameterised statements or prepared statements.

Generally we pass parameters in text format, but binary strings are the exception. We also pass nulls in binary format, so this function need not handle null values.

References text.

Referenced by pqxx::params::make_c_params().

◆ parse_composite() [1/2]

template<typename... T>

void pqxx::parse_composite	(	pqxx::internal::encoding_group	enc,
		std::string_view	text,
		T &...	fields
	)

Parse a string representation of a value of a composite type.

Warning: This code is still experimental. Use with care.

You may use this as a helper while implementing your own string_traits for a composite type.

This function interprets text as the string representation of a value of some composite type, and sets each of fields to the respective values of its fields. The field types must be copy-assignable.

The number of fields must match the number of fields in the composite type, and there must not be any other text in the input. The function is meant to handle any value string that the backend can produce, but not necessarily every valid alternative spelling.

Fields in composite types can be null. When this happens, the C++ type of the corresponding field reference must be of a type that can handle nulls. If you are working with a type that does not have an inherent null value, such as e.g. int, consider using std::optional.

References pqxx::internal::get_glyph_scanner(), and text.

Referenced by pqxx::field::composite_to(), and parse_composite().

◆ parse_composite() [2/2]

template<typename... T>

void pqxx::parse_composite	(	std::string_view	text,
		T &...	fields
	)

Parse a string representation of a value of a composite type.

Warning: This version only works for UTF-8 and single-byte encodings.

For proper encoding support, use the composite-type support in the field class.

References parse_composite(), and text.

◆ perform()

template<typename TRANSACTION_CALLBACK >

auto pqxx::perform	(	TRANSACTION_CALLBACK &&	callback,
		int	attempts = `3`
	)		-> std::invoke_result_t<TRANSACTION_CALLBACK>

Simple way to execute a transaction with automatic retry.

Executes your transaction code as a callback. Repeats it until it completes normally, or it throws an error other than the few libpqxx-generated exceptions that the framework understands, or after a given number of failed attempts, or if the transaction ends in an "in-doubt" state.

(An in-doubt state is one where libpqxx cannot determine whether the server finally committed a transaction or not. This can happen if the network connection to the server is lost just while we're waiting for its reply to a "commit" statement. The server may have completed the commit, or not, but it can't tell you because there's no longer a connection.

Using this still takes a bit of care. If your callback makes use of data from the database, you'll probably have to query that data within your callback. If the attempt to perform your callback fails, and the framework tries again, you'll be in a new transaction and the data in the database may have changed under your feet.

Also be careful about changing variables or data structures from within your callback. The run may still fail, and perhaps get run again. The ideal way to do it (in most cases) is to return your result from your callback, and change your program's data state only after perform completes successfully.

Parameters

callback	Transaction code that can be called with no arguments.
attempts	Maximum number of times to attempt performing callback. Must be greater than zero.

Returns: Whatever your callback returns.

◆ PQXX_DECLARE_ENUM_CONVERSION()

pqxx::PQXX_DECLARE_ENUM_CONVERSION ( ExecStatusType )

◆ separated_list() [1/5]

template<typename CONTAINER >

auto pqxx::separated_list	(	std::string_view	sep,
		CONTAINER const &	c
	)		-> typename std::enable_if< (not std::is_void<decltype(std::begin(c))>::value and not std::is_void<decltype(std::end(c))>::value), std::string>::type

Render items in a container as a string, using given separator.

References separated_list().

◆ separated_list() [2/5]

template<typename ITER >

std::string pqxx::separated_list	(	std::string_view	sep,
		ITER	begin,
		ITER	end
	)

Render sequence as a string, using given separator between items.

References separated_list().

◆ separated_list() [3/5]

template<typename ITER , typename ACCESS >

std::string pqxx::separated_list	(	std::string_view	sep,
		ITER	begin,
		ITER	end,
		ACCESS	access
	)

Represent sequence of values as a string, joined by a given separator.

Use this to turn e.g. the numbers 1, 2, and 3 into a string "1, 2, 3".

Parameters

sep	separator string (to be placed between items)
begin	beginning of items sequence
end	end of items sequence
access	functor defining how to dereference sequence elements

References to_string().

Referenced by pqxx::connection::quote_columns(), pqxx::connection::quote_table(), and separated_list().

◆ separated_list() [4/5]

template<typename TUPLE , std::size_t INDEX = 0, typename std::enable_if<(INDEX<=std::tuple_size< TUPLE >::value), int >::type = 0>

std::string pqxx::separated_list	(	std::string_view	sep,
		TUPLE const &	t
	)

References separated_list().

◆ separated_list() [5/5]

template<typename TUPLE , std::size_t INDEX = 0, typename ACCESS , typename std::enable_if<(INDEX==std::tuple_size< TUPLE >::value - 1), int >::type = 0>

std::string pqxx::separated_list	(	std::string_view	sep,
		TUPLE const &	t,
		ACCESS const &	access
	)

Render items in a tuple as a string, using given separator.

References to_string().

◆ size_buffer()

template<typename... TYPE>

std::size_t pqxx::size_buffer ( TYPE const &... value )

noexcept

Estimate how much buffer space is needed to represent values as a string.

The estimate may be a little pessimistic, if it saves time. It also includes room for a terminating zero after each value.

◆ skip_init_ssl()

template<skip_init... SKIP>

void pqxx::skip_init_ssl ( )

noexcept

Control initialisation of OpenSSL and libcrypto libraries.

By default, libpq initialises the openssl and libcrypto libraries when your process first opens an SSL connection to a database. But this may not be what you want: perhaps your application (or some other library it uses) already initialises one or both of these libraries.

Call this function to stop libpq from initialising one or the other of these. Pass as arguments each of the skip_init flags for which of the libraries whose initialisation you want to prevent.

Warning: Each call to this function overwrites the effects of any previous call. So if you make one call to skip OpenSSL initialisation, and then another to skip libcrypto initialisation, the first call will do nothing.

Examples:

To let libpq initialise libcrypto but not OpenSSL: skip_init_ssl<pqxx::skip_init::openssl>();
To let libpq know that it should not initialise either:
skip_init_ssl<pqxx::skip_init::openssl, pqxx::skip_init::crypto>();
To say explicitly that you want libpq to initialise both: skip_init_ssl<pqxx::skip_init::nothing>();

References pqxx::internal::skip_init_ssl().

◆ to_buf()

template<typename... TYPE>

std::vector<std::string_view> pqxx::to_buf	(	char *	here,
		char const *	end,
		TYPE...	value
	)

Convert multiple values to strings inside a single buffer.

There must be enough room for all values, or this will throw conversion_overrun. You can obtain a conservative estimate of the buffer space required by calling size_buffer() on the values.

The std::string_view results may point into the buffer, so don't assume that they will remain valid after you destruct or move the buffer.

◆ to_string() [1/2]

template<>

std::string pqxx::to_string ( field const & value )

Convert a field to a string.

References pqxx::field::c_str().

Referenced by pqxx::connection::adorn_name(), pqxx::params::append(), pqxx::binarystring::at(), pqxx::connection::quote(), separated_list(), and pqxx::result::table_column().

◆ to_string() [2/2]

template<typename TYPE >

std::string pqxx::to_string ( TYPE const & value )

Convert a value to a readable string that PostgreSQL will understand.

The conversion does no special formatting, and ignores any locale settings. The resulting string will be human-readable and in a format suitable for use in SQL queries. It won't have niceties such as "thousands separators" though.

◆ transaction_base::query_value< std::string_view >()

template<>

std::string_view pqxx::transaction_base::query_value< std::string_view >	(	zview	query,
		std::string_view	desc
	)

delete

Forbidden specialisation: underlying buffer immediately goes out of scope.

Variable Documentation

◆ array_separator

template<typename T >

constexpr char pqxx::array_separator {','}

constexpr

Element separator between SQL array elements of this type.

◆ from_query

constexpr from_query_t pqxx::from_query

constexpr

Pass this to a stream_from constructor to stream query results.

Deprecated:: Use transaction_base::stream instead of stream_from.

Referenced by pqxx::stream_from::query().

◆ from_table

constexpr from_table_t pqxx::from_table

constexpr

Pass this to a stream_from constructor to stream table contents.

Deprecated:: Use transaction_base::stream instead of stream_from.

Referenced by pqxx::stream_from::raw_table().

◆ has_generic_bytes_char_traits

constexpr bool pqxx::has_generic_bytes_char_traits

constexpr

Initial value:

=

has_generic_char_traits<std::byte>::value

◆ is_sql_array

template<typename TYPE >

constexpr bool pqxx::is_sql_array {false}

constexpr

Does this type translate to an SQL array?

Specialisations may override this to be true for container types.

This may not always be a black-and-white choice. For instance, a std::string is a container, but normally it translates to an SQL string, not an SQL array.

◆ is_unquoted_safe

template<typename TYPE >

constexpr bool pqxx::is_unquoted_safe {false}

constexpr

Can we use this type in arrays and composite types without quoting them?

Define this as true only if values of TYPE can never contain any special characters that might need escaping or confuse the parsing of array or composite * types, such as commas, quotes, parentheses, braces, newlines, and so on.

When converting a value of such a type to a string in an array or a field in a composite type, we do not need to add quotes, nor escape any special characters.

This is just an optimisation, so it defaults to false to err on the side of slow correctness.

◆ oid_none

constexpr oid pqxx::oid_none {0}

constexpr

The "null" oid.

Referenced by pqxx::result::column_table(), pqxx::result::column_type(), pqxx::largeobject::largeobject(), pqxx::largeobjectaccess::read(), pqxx::largeobject::remove(), pqxx::largeobjectaccess::seek(), pqxx::largeobject::to_file(), and pqxx::largeobjectaccess::write().

◆ type_name

template<typename TYPE >

std::string const pqxx::type_name {internal::demangle_type_name(typeid(TYPE).name())}

A human-readable name for a type, used in error messages and such.

Actually this may not always be very user-friendly. It uses std::type_info::name(). On gcc-like compilers we try to demangle its output. Visual Studio produces human-friendly names out of the box.

This variable is not inline. Inlining it gives rise to "memory leak" warnings from asan, the address sanitizer, possibly from use of std::type_info::name.

Namespaces

Classes

Typedefs

Enumerations

Functions

Variables

Detailed Description

Typedef Documentation

◆ bytes

◆ bytes_view

◆ connection_base

◆ field_size_type

◆ fieldstream

◆ ilostream

◆ large_object_size_type

◆ lostream

◆ olostream

◆ read_transaction

◆ result_difference_type

◆ result_size_type

◆ row_difference_type

◆ row_size_type

◆ strip_t

◆ table_path

◆ value_type

◆ work

Enumeration Type Documentation

◆ error_verbosity

◆ format

◆ isolation_level

◆ skip_init

◆ write_policy

Function Documentation

◆ binary_cast() [1/2]

◆ binary_cast() [2/2]

◆ check_cast()

◆ check_version()

◆ composite_into_buf()

◆ composite_size_buffer()

◆ describe_thread_safety()

◆ encrypt_password() [1/2]

◆ encrypt_password() [2/2]

◆ field::as< std::string_view >() [1/2]

◆ field::as< std::string_view >() [2/2]

◆ field::to< std::string >() [1/2]

◆ field::to< std::string >() [2/2]

◆ field::to< std::string_view >() [1/2]

◆ field::to< std::string_view >() [2/2]

◆ from_string() [1/4]

◆ from_string() [2/4]

◆ from_string() [3/4]

◆ from_string() [4/4]

◆ from_string< std::nullptr_t >()

◆ generic_to_buf()

◆ ignore_unused()

◆ into_string()

◆ is_null()

◆ oops_forbidden_conversion()

◆ operator""_zv()

◆ operator+()

◆ operator<<()

◆ param_format()

◆ parse_composite() [1/2]

◆ parse_composite() [2/2]

◆ perform()

◆ PQXX_DECLARE_ENUM_CONVERSION()

◆ separated_list() [1/5]

◆ separated_list() [2/5]

◆ separated_list() [3/5]

◆ separated_list() [4/5]

◆ separated_list() [5/5]

◆ size_buffer()

◆ skip_init_ssl()

◆ to_buf()

◆ to_string() [1/2]

◆ to_string() [2/2]

◆ transaction_base::query_value< std::string_view >()

Variable Documentation

◆ array_separator

◆ from_query