pg_escape_bytea

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

pg_escape_bytea — Escape a string for insertion into a bytea field

Description

string pg_escape_bytea ([ resource $connection ], string $data )

pg_escape_bytea() escapes string for bytea datatype. It returns escaped string.

Note:
When you SELECT a bytea type, PostgreSQL returns octal byte values prefixed with '\' (e.g. \032). Users are supposed to convert back to binary format manually.

This function requires PostgreSQL 7.2 or later. With PostgreSQL 7.2.0 and 7.2.1, bytea values must be cast when you enable multi-byte support. i.e. INSERT INTO test_table (image) VALUES ('$image_escaped'::bytea); PostgreSQL 7.2.2 or later does not need a cast. The exception is when the client and backend character encoding does not match, and there may be multi-byte stream error. User must then cast to bytea to avoid this error.

Parameters

connection: PostgreSQL database connection resource. When connection is not present, the default connection is used. The default connection is the last connection made by pg_connect() or pg_pconnect().
data: A string containing text or binary data to be inserted into a bytea column.

Return Values

A string containing the escaped data.

Changelog

Version	Description
5.2.0	`connection` added

Examples

Example #1 pg_escape_bytea() example


<?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
  $escaped = pg_escape_bytea($data);
  
  // Insert it into the database
  pg_query("INSERT INTO gallery (name, data) VALUES ('Pine trees', '{$escaped}')");
?>

User Contributed Notes

Mike-RaWare

5 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);
?>

Mocha

12 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;

}

?>

Michael

2 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')");
?>

gglockner AT NOSPAMdwaffler DOT com

6 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)");

?>

ynzhang from lakeheadu of ca

7 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

php at tobias dot olsson dot be

13 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