pg_escape_bytea

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_escape_bytea — Escapar un string para insertarlo en un campo bytea

Descripción

pg_escape_bytea(resource $connection = ?, string $data): string

pg_escape_bytea() escapa un string para un tipo de dato bytea. Devuelve un string pasado por un proceso de escape.

Nota:
Cuando haces una consulta SELECT a un tipo bytea, PostgreSQL devuelve valores de byte octal con el prefijo '\' (ej. \032). Los usuarios están supuestos a convertirlo de regreso al formato binario manualmente.

Esta función requiere PostgreSQL versión 7.2 o posterior. Con la versión 7.2.0 y 7.2.1 de PostgreSQL, los valores bytea deben ser pasados por un casteo cuando se habilita soporte multi-byte. Ej. INSERT INTO test_table (image) VALUES ('$image_escaped'::bytea); PostgreSQL 7.2.2 o una versión posterior no necesita un casteo. La excepción es cuando la codificación de caracteres del cliente y del servidor no coinciden, y podría haber un flujo de error multi-byte. Entonces el usuario debe castear a bytea para evitar este error.

Parámetros

connection: Recurso de conexión a la base de datos PostgreSQL. Cuando el parámetro connection no está presente, se utiliza la conexión predeterminada. La conexión predeterminada es la última conexión hecha por pg_connect() o pg_pconnect().
data: Un tipo de dato string que contiene datos de texto o binarios para ser insertados dentro de una columna bytea.

Valores devueltos

Un tipo de dato string que contiene los datos que han sido escapados.

Historial de cambios

Versión	Descripción
5.2.0	Se agregó el parámetro `connection`

Ejemplos

Ejemplo #1 Ejemplo de pg_escape_bytea()

<?php 
  // Connectar a la base de datos
  $dbconn = pg_connect('dbname=foo');
  
  // Leer en un fichero binario
  $data = file_get_contents('image1.jpg');
  
  // Escapar el dato binario
  $escaped = pg_escape_bytea($data);
  
  // Insertarlo en la base de datos
  pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', '{$escaped}')");
?>

Ver también

pg_unescape_bytea() - Unescape binary for bytea type
pg_escape_string() - Escape a string for query

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User Contributed Notes 8 notes

down

ynzhang from lakeheadu of ca ¶

15 years ago

The reason pg_unescape_bytea() do not exactly reproduce the binary data created by pg_escape_bytea() is because the backslash \ and single quote ' are double escaped by the pg_escape_bytea() function. This will lead to image seems corrupted when retrieve from the bytea field. The proper way to escape&unescape a binary string into a PG bytea field as follow:



<?php

$escaped_data = str_replace(array("\\\\", "''"), array("\\", "'"), pg_escape_bytea($data));

/* and later unescape the escaped data from the bytea field with following to get the original binary data */



$original_data = pg_unescape_bytea($escaped_data));

?>



more details at: http://archives.postgresql.org/pgsql-php/2007-02/msg00014.php

down

Hayley Watson ¶

7 years ago

PostgreSQL 9.0 introduced a new hexadecimal-based representation for bytea data that is preferred over the escaping mechanism implemented by this function.

<?php
function pg_escape_byteahex($binary)
{
    return "E'\\\\x".bin2hex($binary)."'";
}
?>

down

Mike-RaWare ¶

14 years ago

To prevent any problems with encoding you could use hexadecimal or base64 input to save and retrieve data to the database:

<?php 
  // Connect to the database
  $dbconn = pg_connect( 'dbname=foo' );
  
  // Read in a binary file
  $data = file_get_contents( 'image1.jpg' );
  
  // Escape the binary data
  $escaped = bin2hex( $data );
  
  // Insert it into the database
  pg_query( "INSERT INTO gallery (name, data) VALUES ('Pine trees', decode('{$escaped}' , 'hex'))" );

  // Get the bytea data
  $res = pg_query("SELECT encode(data, 'base64') AS data FROM gallery WHERE name='Pine trees'");  
  $raw = pg_fetch_result($res, 'data');
  
  // Convert to binary and send to the browser
  header('Content-type: image/jpeg');
  echo base64_decode($raw);
?>

down

Mocha ¶

21 years ago

to unescape_bytea use stripcslashes(). If you need to escape bytea and don't have pg_escape_bytea() function then use:



<?php

function escByteA($binData) {

  /**

   * \134 = 92 = backslash, \000 = 00 = NULL, \047 = 39 = Single Quote

   *

   * str_replace() replaces the searches array in order. Therefore, we must

   * process the 'backslash' character first. If we process it last, it'll

   * replace all the escaped backslashes from the other searches that came

   * before.

   */

  $search = array(chr(92), chr(0), chr(39));

  $replace = array('\\\134', '\\\000', '\\\047');

  $binData = str_replace($search, $replace, $binData);

  return $binData;

  //echo "<pre>$binData</pre>";

  //exit;

}

?>

down

tabflo at gmx dot at ¶

3 months ago

this method des the same as pg_escape_bytea have fun with it:

public function escape_bytea($data) {
        $escaped = '';

        for ($i = 0; $i < strlen($data); $i++) {
            $char = $data[$i];
            $ascii = ord($char);

            $escaped.= ($ascii < 32 || $ascii > 126 ? sprintf('\\%03o', $ascii) : ($char == '\\' ? '\\\\' : $char) );
        }
        return $escaped;
    }

down

Michael ¶

10 years ago

using  pg_escape_bytea without 'E' escape tag
<?php 
  // Die Binärdaten maskieren
  $escaped = pg_escape_bytea($data);

  // und in die Datenbank einfügen (falsch/wrong)
  pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', E'$escaped')");

  // und in die Datenbank einfügen (richtig/right)
  pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', '$escaped')");
?>

down

gglockner AT NOSPAMdwaffler DOT com ¶

15 years ago

If you're getting errors about nonstandard use of \\ in a string literal, then you need to escape the encoded bytea as follows:



<?php

$escaped = pg_escape_bytea($data);

pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', E'$escaped'::bytea)");

?>

down

-3

php at tobias dot olsson dot be ¶

22 years ago

if you need to change back bytea from the db to normal data, this will do that:



<?php

function pg_unescape_bytea($bytea) {

return eval("return \"".str_replace('$', '\\$', str_replace('"', '\\"', $bytea))."\";");

}



// use like this

$rs = pg_query($conn, "SELECT image from images LIMIT 1");

$image = pg_unescape_bytea(pg_fetch_result($rs, 0, 0));

?>



/Tobias

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