passing arrays as url parameter

Question

hi,

what is the best way that i can pass an array as a url parameter? i was thinking if this is possible:

$aValues = array();

$url = 'http://www.example.com?aParam='.$aValues;

or how about this:

$url = 'http://www.example.com?aParam[]='.$aValues;

Ive read examples, but i find it messy:

$url = 'http://www.example.com?aParam[]=value1&aParam[]=value2&aParam[]=value3';

Thanks in advance.

Answer 1

please escape your variables when outputting (urlencode).

and you can’t just print an array, you have to build your url using a loop in some way

$url = 'http://example.com/index.php?'
$first = true;
foreach($aValues as $key => $value) {
  if(!$first) $url .= '&amp';
  else $first = false;
  $url .= 'aValues['.urlencode($key).']='.urlencode($value);
}

Answer 2

Easiest way would be to use the serialize function.

It serializes any variable for storage or transfer. You can read about it in the php manual - serialize

The variable can be restored by using unserialize

So in the passing to the URL you use:

$url = urlencode(serialize($array))

and to restore the variable you use

$var = unserialize(urldecode($_GET['array']))

Be careful here though. The maximum size of a GET request is limited to 4k, which you can easily exceed by passing arrays in a URL.

Also, its really not quite the safest way to pass data! You should probably look into using sessions instead.

Answer 3

knittl is right on about escaping. However, there's a simpler way to do this:

$url = 'http://example.com/index.php?';
$url .= 'aValues[]=' . implode('&aValues[]=', array_map('urlencode', $aValues));

If you want to do this with an associative array, try this instead:

PHP 5.3+ (lambda function)

$url = 'http://example.com/index.php?';
$url .= implode('&', array_map(function($key, $val) {
    return 'aValues[' . urlencode($key) . ']=' . urlencode($val);
  },
  array_keys($aValues), $aValues)
);

PHP <5.3 (callback)

function urlify($key, $val) {
  return 'aValues[' . urlencode($key) . ']=' . urlencode($val);
}

$url = 'http://example.com/index.php?';
$url .= implode('&', array_map('urlify', array_keys($aValues), $aValues));

Answer 4

There is a very simple solution: http_build_query(). It takes your query parameters as an associative array:

$data = array(
    1,
    4,
    'a' => 'b',
    'c' => 'd'
);
$query = http_build_query(array('aParam' => $data));

will return

string(63) "aParam%5B0%5D=1&aParam%5B1%5D=4&aParam%5Ba%5D=b&aParam%5Bc%5D=d"

http_build_query() handles all the necessary escaping for you (%5B => [ and %5D => ]), so this string is equal to aParam[0]=1&aParam[1]=4&aParam[a]=b&aParam[c]=d.