libpqxx
7.9.0
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Accessor for large object's contents. More...
#include <largeobject.hxx>
Public Types | |
using | off_type = size_type |
using | pos_type = size_type |
using | openmode = std::ios::openmode |
Open mode: in , out (can be combined using "bitwise or"). 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=default_mode) | |
Create new large object and open it. More... | |
largeobjectaccess (dbtransaction &t, oid o, openmode mode=default_mode) | |
Open large object with given oid. More... | |
largeobjectaccess (dbtransaction &t, largeobject o, openmode mode=default_mode) | |
Open given large object. More... | |
largeobjectaccess (dbtransaction &t, std::string_view file, openmode mode=default_mode) | |
Import large object from a local file and open it. More... | |
~largeobjectaccess () noexcept | |
void | to_file (std::string_view file) const |
Export large object's contents to a local file. More... | |
oid | id () const noexcept |
Object identifier. More... | |
void | to_file (dbtransaction &t, std::string_view file) const |
Export large object's contents to a local file. More... | |
High-level access to object contents. | |
void | write (char const buf[], std::size_t len) |
Write data to large object. More... | |
void | write (std::string_view buf) |
Write string to large object. More... | |
size_type | read (char buf[], std::size_t 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. Due to libpq's underlying API, some operations are limited to "int" sizes, typically 2 GB, even though a large object can grow much larger. | |
pos_type | cseek (off_type dest, seekdir dir) noexcept |
Seek in large object's data stream. More... | |
off_type | cwrite (char const buf[], std::size_t len) noexcept |
Write to large object's data stream. More... | |
off_type | cread (char buf[], std::size_t 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... | |
Static Public Attributes | |
static constexpr auto | default_mode |
Default open mode: in, out, binary. More... | |
Error/warning output | |
void | process_notice (zview) noexcept |
Issue message to transaction's notice processor. More... | |
largeobjectaccess ()=delete | |
largeobjectaccess (largeobjectaccess const &)=delete | |
largeobjectaccess | operator= (largeobjectaccess const &)=delete |
void | remove (dbtransaction &t) const |
Delete large object from database. More... | |
bool | operator== (largeobject const &other) const |
Compare object identities. More... | |
bool | operator!= (largeobject const &other) const |
Compare object identities. More... | |
bool | operator< (largeobject const &other) const |
Compare object identities. More... | |
bool | operator<= (largeobject const &other) const |
Compare object identities. More... | |
bool | operator> (largeobject const &other) const |
Compare object identities. More... | |
bool | operator>= (largeobject const &other) const |
Compare object identities. More... | |
Accessor for large object's contents.
blob
class instead. using pqxx::largeobjectaccess::openmode = std::ios::openmode |
Open mode: in
, out
(can be combined using "bitwise or").
According to the C++ standard, these should be in std::ios_base
. We take them from derived class std::ios
instead, which is easier on the eyes.
Historical note: taking it from std::ios was originally a workaround for a problem with gcc 2.95.
using pqxx::largeobjectaccess::seekdir = std::ios::seekdir |
Seek direction: beg
, cur
, end
.
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explicit |
Create new large object and open it.
t | Backend transaction in which the object is to be created. |
mode | Access mode, defaults to ios_base::in | ios_base::out | ios_base::binary. |
PQXX_COLD pqxx::largeobjectaccess::largeobjectaccess | ( | dbtransaction & | t, |
oid | o, | ||
openmode | mode = default_mode |
||
) |
Open large object with given oid.
Convert combination of a transaction and object identifier into a large object identity. Does not affect the database.
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 | ios_base::binary. |
PQXX_COLD pqxx::largeobjectaccess::largeobjectaccess | ( | dbtransaction & | t, |
largeobject | o, | ||
openmode | mode = default_mode |
||
) |
Open given large object.
Open a large object with the given identity for reading and/or writing.
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 | ios_base::binary. |
PQXX_COLD pqxx::largeobjectaccess::largeobjectaccess | ( | dbtransaction & | t, |
std::string_view | file, | ||
openmode | mode = default_mode |
||
) |
Import large object from a local file and open it.
Creates a large object containing the data found in the given file.
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. |
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noexcept |
|
delete |
|
delete |
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noexcept |
Read from large object's data stream.
Does not throw exception in case of error; inspect return value and errno
instead.
buf | Area where incoming bytes should be stored. |
len | Number of bytes to read. |
|
noexcept |
Seek in large object's data stream.
Does not throw exception in case of error; inspect return value and errno
instead.
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). |
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noexcept |
Report current position in large object's data stream.
Does not throw exception in case of error; inspect return value and errno
instead.
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noexcept |
Write to large object's data stream.
Does not throw exception in case of error; inspect return value and errno
instead.
buf | Data to write. |
len | Number of bytes to write. |
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noexcept |
Object identifier.
The number returned by this function uniquely identifies the large object in the context of the database we're connected to.
bool pqxx::largeobject::operator!= |
Compare object identities.
bool pqxx::largeobject::operator< |
Compare object identities.
bool pqxx::largeobject::operator<= |
Compare object identities.
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delete |
References pqxx::largeobject::raw_connection().
bool pqxx::largeobject::operator== |
Compare object identities.
bool pqxx::largeobject::operator> |
Compare object identities.
bool pqxx::largeobject::operator>= |
Compare object identities.
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noexcept |
Issue message to transaction's notice processor.
pqxx::largeobjectaccess::size_type PQXX_COLD pqxx::largeobjectaccess::read | ( | char | buf[], |
std::size_t | len | ||
) |
Read data from large object.
Throws an exception if an error occurs while reading.
buf | Location to store the read data in. |
len | Number of bytes to try and read. |
References pqxx::oid_none.
void PQXX_COLD pqxx::largeobject::remove |
Delete large object from database.
Unlike its low-level equivalent cunlink, this will throw an exception if deletion fails.
t | Transaction in which the object is to be deleted |
pqxx::largeobjectaccess::size_type PQXX_COLD pqxx::largeobjectaccess::seek | ( | size_type | dest, |
seekdir | dir | ||
) |
Seek in large object's data stream.
Throws an exception if an error occurs.
References pqxx::oid_none.
pqxx::largeobjectaccess::size_type PQXX_COLD pqxx::largeobjectaccess::tell | ( | ) | const |
Report current position in large object's data stream.
Throws an exception if an error occurs.
void PQXX_COLD pqxx::largeobject::to_file |
Export large object's contents to a local file.
Writes the data stored in the large object to the given file.
t | Transaction in which the object is to be accessed |
file | A filename on the client's filesystem |
void pqxx::largeobjectaccess::to_file | ( | std::string_view | file | ) | const |
Export large object's contents to a local file.
Writes the data stored in the large object to the given file.
file | A filename on the client's filesystem. |
References pqxx::largeobject::to_file().
void PQXX_COLD pqxx::largeobjectaccess::write | ( | char const | buf[], |
std::size_t | len | ||
) |
Write data to large object.
buf | Data to write. |
len | Number of bytes from Buf to write. |
References pqxx::internal::cmp_less(), and pqxx::oid_none.
void pqxx::largeobjectaccess::write | ( | std::string_view | buf | ) |
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staticconstexpr |
Default open mode: in, out, binary.