PDO::pgsqlLOBOpen

(PHP 5 >= 5.1.2, PHP 7, PHP 8, PECL pdo_pgsql >= 1.0.2)

PDO::pgsqlLOBOpen — Ouvre un flux existant de large objet

Description

public PDO::pgsqlLOBOpen(string $oid, string $mode = "rb"): resource|false

PDO::pgsqlLOBOpen() ouvre un flux pour accéder aux données référencées par oid. Si mode est r, le flux est ouvert en lecture, si mode est w, alors le flux sera ouvert en écriture. Vous pouvez utilisez toutes les fonctions usuelles de système de fichiers, comme fread(), fwrite() et fgets() pour manipuler le contenu du flux.

Note: Cette fonction, ainsi que toutes les manipulations sur l'objet large, doit être appelée et exécutée à l'intérieur d'une transaction.

Liste de paramètres

oid: Un identifiant d'objet large
mode: Si le mode est r, ouverture du flux en lecture. Si le mode est w, ouverture du flux en écriture.

Valeurs de retour

Retourne une ressource de flux en cas de succès ou false si une erreur survient.

Exemples

Exemple #1 Exemple avec PDO::pgsqlLOBOpen()

Suivant l'exemple de PDO::pgsqlLOBCreate(), cet partie de code récupère l'objet large de la base de données et l'affiche au navigateur.

<?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);
?>

Voir aussi

PDO::pgsqlLOBCreate() - Crée un nouvel objet large
PDO::pgsqlLOBUnlink() - Supprime un objet large
pg_lo_open() - Ouvre un objet de grande taille PostgreSQL

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User Contributed Notes 3 notes

down

binaryexp at gmail ¶

15 years ago

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.

down

knl at bitflop dot com ¶

15 years ago

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.

down

knl at bitflop dot com ¶

15 years ago

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.

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