PDO::pgsqlLOBOpen
(PHP 5 >= 5.1.2, PHP 7, PECL pdo_pgsql >= 1.0.2)
PDO::pgsqlLOBOpen — Opens an existing large object stream
Описание
$oid
[, string $mode = "rb"
] )
PDO::pgsqlLOBOpen() opens a stream to access the data
referenced by oid. If mode
is r, the stream is opened for reading, if
mode is w, then the stream will
be opened for writing. You can use all the usual filesystem functions,
such as fread(), fwrite() and
fgets() to manipulate the contents of the stream.
Замечание: This function, and all manipulations of the large object, must be called and carried out within a transaction.
Список параметров
-
oid -
A large object identifier.
-
mode -
If mode is r, open the stream for reading. If mode is w, open the stream for writing.
Возвращаемые значения
Returns a stream resource on success или FALSE в случае возникновения ошибки.
Примеры
Пример #1 A PDO::pgsqlLOBOpen() example
Following on from the PDO::pgsqlLOBCreate() example, this code snippet retrieves the large object from the database and outputs it to the browser.
<?php
$db = new PDO('pgsql:dbname=test host=localhost', $user, $pass);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->beginTransaction();
$stmt = $db->prepare("select oid from BLOBS where ident = ?");
$stmt->execute(array($some_id));
$stmt->bindColumn('oid', $oid, PDO::PARAM_STR);
$stmt->fetch(PDO::FETCH_BOUND);
$stream = $db->pgsqlLOBOpen($oid, 'r');
header("Content-type: application/octet-stream");
fpassthru($stream);
?>
Смотрите также
- PDO::pgsqlLOBCreate() - Creates a new large object
- PDO::pgsqlLOBUnlink() - Deletes the large object
- pg_lo_open() - Открывает большой объект базы данных
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для работы с базами данных
- Уровни абстракции
- Объекты данных PHP
- PDO Драйверы
- Функция PDO_PGSQL DSN() - Connecting to PostgreSQL databases
- PDO::pgsqlCopyFromArray
- PDO::pgsqlCopyFromFile
- PDO::pgsqlCopyToArray
- PDO::pgsqlCopyToFile
- PDO::pgsqlGetNotify
- PDO::pgsqlGetPid
- Функция PDO::pgsqlLOBCreate() - Creates a new large object
- Функция PDO::pgsqlLOBOpen() - Opens an existing large object stream
- Функция PDO::pgsqlLOBUnlink() - Deletes the large object
Коментарии
The above example is missing some data. After spending several hours trying to get it to work in vain, Jeff Davis from the PostgreSQL channel on IRC (freenode) figured out what was missing.
The below example will work, but you have to insert the MIME type and file size of the large object that you are storing, so you can use that data for extraction.
<?php
$db = new PDO('pgsql:dbname=test host=localhost', $user, $pass);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->beginTransaction();
$stmt = $db->prepare("SELECT oid, blob_type, filesize FROM BLOBS WHERE ident = ?");
$stmt->execute(array($some_id));
$stmt->bindColumn('oid', $lob, PDO::PARAM_LOB);
$stmt->bindColumn('blob_type', $blob_type, PDO::PARAM_STR);
$stmt->bindColumn('filesize', $filesize, PDO::PARAM_STR);
$stmt->fetch(PDO::FETCH_BOUND);
$stream = $pdo->pgsqlLOBOpen($lob, 'r');
$data = fread($stream, $filesize);
header("Content-type: $blob_type");
echo $data;
?>
Also fpassthru() will just give this result: Warning: fpassthru(): supplied argument is not a valid stream resource in ...
Use echo or print instead.
Also remember that fread() will only parse the first 8192 bytes from the stream. Use..
<?php
$data = stream_get_contents($stream);
?>
.. if you have a larger output to parse.
This is what worked for me. If you have the oid, then all you need to do is:
<?php
$pdo = new PDO($dsn, $user, $pass);
$pdo->beginTransaction();
$data = $pdo->pgsqlLOBOpen($oid, 'r');
header("Content-Type: $mime");
// any other headers...
fpassthru($data); // echo stream_get_contents($data); also works
?>
The beginTransaction() is required, if you want to $pdo->commit() (it's not required) then do it after the fpassthru.
On a side note, those using Zend Framework can call getConnection() on the standard PDO database object which will get them the $pdo object as above. Then just remember to disableLayout() and setNoRender() as necessary.