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

#include <largeobject.hxx>

Inheritance diagram for pqxx::largeobjectaccess:

Public Types
using	off_type = long

using	pos_type = size_type

using	openmode = std::ios::openmode
	Open mode: `in`, `out` (can be combined with the "or" operator) More...

using	seekdir = std::ios::seekdir
	Seek direction: `beg`, `cur`, `end`. More...

using	size_type = large_object_size_type

Public Member Functions
	largeobjectaccess (dbtransaction &T, openmode mode=std::ios::in\|std::ios::out)
	Create new large object and open it. More...

	largeobjectaccess (dbtransaction &T, oid O, openmode mode=std::ios::in\|std::ios::out)
	Open large object with given oid. More...

	largeobjectaccess (dbtransaction &T, largeobject O, openmode mode=std::ios::in\|std::ios::out)
	Open given large object. More...

	largeobjectaccess (dbtransaction &T, const std::string &File, openmode mode=std::ios::in\|std::ios::out)
	Import large object from a local file and open it. More...

	~largeobjectaccess () noexcept

void	to_file (const std::string &File) const
	Export large object's contents to a local file. More...

High-level access to object contents
void	write (const char Buf[], size_type Len)
	Write data to large object. More...

void	write (const std::string &Buf)
	Write string to large object. More...

size_type	read (char Buf[], size_type Len)
	Read data from large object. More...

size_type	seek (size_type dest, seekdir dir)
	Seek in large object's data stream. More...

size_type	tell () const
	Report current position in large object's data stream. More...

Low-level access to object contents
These functions provide a more "C-like" access interface, returning special values instead of throwing exceptions on error. These functions are generally best avoided in favour of the high-level access functions, which behave more like C++ functions should.
pos_type	cseek (off_type dest, seekdir dir) noexcept
	Seek in large object's data stream. More...

off_type	cwrite (const char Buf[], size_type Len) noexcept
	Write to large object's data stream. More...

off_type	cread (char Buf[], size_type Len) noexcept
	Read from large object's data stream. More...

pos_type	ctell () const noexcept
	Report current position in large object's data stream. More...

Error/warning output
void	process_notice (const std::string &) noexcept
	Issue message to transaction's notice processor. More...

Detailed Description

Accessor for large object's contents.

Member Typedef Documentation

◆ off_type

using pqxx::largeobjectaccess::off_type = long

◆ openmode

using pqxx::largeobjectaccess::openmode = std::ios::openmode

Open mode: in, out (can be combined with the "or" operator)

According to the C++ standard, these should be in std::ios_base. We take them from std::ios instead, which should be safe because it inherits the same definition, to accommodate gcc 2.95 & 2.96.

◆ pos_type

using pqxx::largeobjectaccess::pos_type = size_type

◆ seekdir

using pqxx::largeobjectaccess::seekdir = std::ios::seekdir

Seek direction: beg, cur, end.

According to the C++ standard, these should be in std::ios_base. We take them from std::ios instead, which should be safe because it inherits the same definition, to accommodate gcc 2.95 & 2.96.

◆ size_type

using pqxx::largeobject::size_type = large_object_size_type

Constructor & Destructor Documentation

◆ largeobjectaccess() [1/4]

pqxx::largeobjectaccess::largeobjectaccess	(	dbtransaction &	T,
		openmode	mode = `std::ios::in\|std::ios::out`
	)

explicit

Create new large object and open it.

Parameters

T	Backend transaction in which the object is to be created
mode	Access mode, defaults to ios_base::in \| ios_base::out

References largeobjectaccess().

Referenced by largeobjectaccess().

◆ largeobjectaccess() [2/4]

pqxx::largeobjectaccess::largeobjectaccess	(	dbtransaction &	T,
		oid	O,
		openmode	mode = `std::ios::in\|std::ios::out`
	)

Open large object with given oid.

Convert combination of a transaction and object identifier into a large object identity. Does not affect the database.

Parameters

T	Transaction in which the object is to be accessed
O	Object identifier for the given object
mode	Access mode, defaults to ios_base::in \| ios_base::out

References largeobjectaccess().

◆ largeobjectaccess() [3/4]

pqxx::largeobjectaccess::largeobjectaccess	(	dbtransaction &	T,
		largeobject	O,
		openmode	mode = `std::ios::in\|std::ios::out`
	)

Open given large object.

Open a large object with the given identity for reading and/or writing

Parameters

T	Transaction in which the object is to be accessed
O	Identity for the large object to be accessed
mode	Access mode, defaults to ios_base::in \| ios_base::out

References largeobjectaccess().

◆ largeobjectaccess() [4/4]

pqxx::largeobjectaccess::largeobjectaccess	(	dbtransaction &	T,
		const std::string &	File,
		openmode	mode = `std::ios::in\|std::ios::out`
	)

Import large object from a local file and open it.

Creates a large object containing the data found in the given file.

Parameters

T	Backend transaction in which the large object is to be created
File	A filename on the client program's filesystem
mode	Access mode, defaults to ios_base::in \| ios_base::out

References largeobjectaccess().

◆ ~largeobjectaccess()

pqxx::largeobjectaccess::~largeobjectaccess ( )

noexcept

References pqxx::largeobject::id().

Member Function Documentation

◆ cread()

pqxx::largeobjectaccess::pos_type pqxx::largeobjectaccess::cread	(	char	Buf[],
		size_type	Len
	)

noexcept

Read from large object's data stream.

Does not throw exception in case of error; inspect return value and errno instead.

Parameters

Buf	Area where incoming bytes should be stored
Len	Number of bytes to read

Returns: Number of bytes actually read, or -1 if an error occurred.

Referenced by read().

◆ cseek()

pqxx::largeobjectaccess::pos_type pqxx::largeobjectaccess::cseek	(	off_type	dest,
		seekdir	dir
	)

noexcept

Seek in large object's data stream.

Does not throw exception in case of error; inspect return value and errno instead.

Parameters

dest	Offset to go to
dir	Origin to which dest is relative: ios_base::beg (from beginning of the object), ios_base::cur (from current access position), or ios_base;:end (from end of object)

Returns: New position in large object, or -1 if an error occurred.

Referenced by seek().

◆ ctell()

pqxx::largeobjectaccess::pos_type pqxx::largeobjectaccess::ctell ( ) const

noexcept

Report current position in large object's data stream.

Does not throw exception in case of error; inspect return value and errno instead.

Returns: Current position in large object, of -1 if an error occurred.

Referenced by tell().

◆ cwrite()

pqxx::largeobjectaccess::pos_type pqxx::largeobjectaccess::cwrite	(	const char	Buf[],
		size_type	Len
	)

noexcept

Write to large object's data stream.

Does not throw exception in case of error; inspect return value and errno instead.

Parameters

Buf	Data to write
Len	Number of bytes to write

Returns: Number of bytes actually written, or -1 if an error occurred.

Referenced by write().

◆ process_notice()

void pqxx::largeobjectaccess::process_notice ( const std::string & s )

noexcept

Issue message to transaction's notice processor.

References pqxx::transaction_base::process_notice().

◆ read()

pqxx::largeobjectaccess::size_type pqxx::largeobjectaccess::read	(	char	Buf[],
		size_type	Len
	)

Read data from large object.

Throws an exception if an error occurs while reading.

Parameters

Buf	Location to store the read data in
Len	Number of bytes to try and read

Returns: Number of bytes read, which may be less than the number requested if the end of the large object is reached

References cread(), and pqxx::to_string().

◆ seek()

pqxx::largeobjectaccess::size_type pqxx::largeobjectaccess::seek	(	size_type	dest,
		seekdir	dir
	)

Seek in large object's data stream.

Throws an exception if an error occurs.

Returns: The new position in the large object

References cseek().

◆ tell()

pqxx::largeobjectaccess::size_type pqxx::largeobjectaccess::tell ( ) const

Report current position in large object's data stream.

Throws an exception if an error occurs.

Returns: The current position in the large object

References pqxx::transaction_base::conn(), ctell(), and pqxx::largeobject::reason().

◆ to_file()

void pqxx::largeobjectaccess::to_file ( const std::string & File ) const

Export large object's contents to a local file.

Writes the data stored in the large object to the given file.

Parameters

File	A filename on the client's filesystem

References pqxx::largeobject::to_file().

◆ write() [1/2]

void pqxx::largeobjectaccess::write	(	const char	Buf[],
		size_type	Len
	)

Write data to large object.

If not all bytes could be written, an exception is thrown.

Parameters

Buf	Data to write
Len	Number of bytes from Buf to write

References cwrite(), and pqxx::to_string().

◆ write() [2/2]

void pqxx::largeobjectaccess::write ( const std::string & Buf )

Write string to large object.

If not all bytes could be written, an exception is thrown.

Parameters

Buf	Data to write; no terminating zero is written

References pqxx::largeobject::raw_connection(), and pqxx::largeobject::remove().

The documentation for this class was generated from the following files:

largeobject.hxx
largeobject.cxx

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ off_type

◆ openmode

◆ pos_type

◆ seekdir

◆ size_type

Constructor & Destructor Documentation

◆ largeobjectaccess() [1/4]

◆ largeobjectaccess() [2/4]

◆ largeobjectaccess() [3/4]

◆ largeobjectaccess() [4/4]

◆ ~largeobjectaccess()

Member Function Documentation

◆ cread()

◆ cseek()

◆ ctell()

◆ cwrite()

◆ process_notice()

◆ read()

◆ seek()

◆ tell()

◆ to_file()

◆ write() [1/2]

◆ write() [2/2]