5.7. Encapsulating Complex Data Types as a String
Problem
You want a string representation of an array or object for storage in a file or database. This string should be easily reconstitutable into the original array or object.
Solution
Use serialize( )
to encode variables and
their values into a textual form:
$pantry = array('sugar' => '2 lbs.','butter' => '3 sticks'); $fp = fopen('/tmp/pantry','w') or die ("Can't open pantry"); fputs($fp,serialize($pantry)); fclose($fp);
To recreate the variables, use unserialize( )
:
$new_pantry = unserialize(join('',file('/tmp/pantry')));
Discussion
The serialized string that is reconstituted into
$pantry
looks like:
a:2:{s:5:"sugar";s:6:"2 lbs.";s:6:"butter";s:8:"3 sticks";}
This stores enough information to bring back all the values in the array, but the variable name itself isn’t stored in the serialized representation.
When passing serialized data from page to page in a URL, call
urlencode( )
on the data to make sure URL
metacharacters are escaped in it:
$shopping_cart = array('Poppy Seed Bagel' => 2, 'Plain Bagel' => 1, 'Lox' => 4); print '<a href="next.php?cart='.urlencode(serialize($shopping_cart)).'">Next</a>';
The magic_quotes_gpc
and
magic_quotes_runtime
configuration settings affect
data being passed to unserialize( )
. If
magic_quotes_gpc
is on
, data
passed in URLs, POST variables, or cookies must be processed with
stripslashes( )
before it’s unserialized:
$new_cart = unserialize(stripslashes($cart)); // if magic_quotes_gpc is ...
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