pg_unescape_bytea
(PHP 4 >= 4.3.0, PHP 5)
pg_unescape_bytea — Unescape binary for bytea type
Description
$data
)pg_unescape_bytea() unescapes PostgreSQL bytea data values. It returns the unescaped string, possibly containing binary data.
Note:
When you SELECT a bytea type, PostgreSQL returns octal byte values prefixed with '\' (e.g. \032). Users are supposed to convert back to binary format manually.
This function requires PostgreSQL 7.2 or later. With PostgreSQL 7.2.0 and 7.2.1, bytea values must be cast when you enable multi-byte support. i.e. INSERT INTO test_table (image) VALUES ('$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.
Return Values
A string containing the unescaped data.
Examples
Example #1 pg_unescape_bytea() example
<?php
// Connect to the database
$dbconn = pg_connect('dbname=foo');
// Get the bytea data
$res = pg_query("SELECT 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 pg_unescape_bytea($raw);
?>
Changelog
| Version | Description |
|---|---|
| 5.5.1 | A warning is thrown if the input string is invalid. |
See Also
- pg_escape_bytea() - Escape a string for insertion into a bytea field
- pg_escape_string() - Escape a string for query
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Коментарии
PostgreSQL 9.0 introduced "hex" as the new default format for encoding binary data. Because "pg_unescape_bytea" only works with the old "escape" format, you need to do pg_query('SET bytea_output = "escape";'); before executing your select queries.
More details can be found here: http://www.postgresql.org/docs/9.0/static/datatype-binary.html
[Ed: Recent PostgreSQL versions support unescaping the "hex" format.]
The workaround is to configure a property in the postgres database for the user, to make postgres behave as the old default.
ALTER USER username SET bytea_output = 'escape';
(or using the pgadmin interface)