PHP: Dynamic URL Question - php

Question

The variable ' $return10 ' (for example) is a url, and I need to append ' &var2=example ' to the end. Like this:
header( "Location: $return10&var2=example" );
header ("Content-Length: 0");
exit;
The challenge is not knowing if the url contained in ' $return10 ' will already have a query string.
Choice A) If I use ' &var2=example ' , then sometimes the final url will be ' ://example.com&var2=example ' , with no '?' to start the query string.
Choice B) If I use ' ?var2=example ' , then sometimes the final url will contain two "?"'s starting two different query strings??
Is there a third choice? How would you cover both possibilities using "the correct code?" Thank you.

Answer 1

Create a function that will append your query code if there is one... And add it if there isn't...
function append_query($url, $query) {
// Fix for relative scheme URL
$relativeScheme = false;
if(substr($url, 0, 3) == '://') {
$relativeScheme = true;
$url = 'a' . $url;
}
$newUrl = http_build_url($url, array('query' => $query), HTTP_URL_JOIN_QUERY);
if($relativeScheme) {
return substr($newUrl, 1);
}
return $newUrl;
}
header('Location: ' . append_query($return10, 'var2=example'));
This will work regardless of if your query has a fragment or not.
EDIT: Fixed for relative scheme URL.
If your PHP does not have http_build_url() available (ie.: PECL extension not installed), here is a pure PHP version of it which does not require the extension.
define('HTTP_URL_REPLACE', 1); // Replace every part of the first URL when there's one of the second URL
define('HTTP_URL_JOIN_PATH', 2); // Join relative paths
define('HTTP_URL_JOIN_QUERY', 4); // Join query strings
define('HTTP_URL_STRIP_USER', 8); // Strip any user authentication information
define('HTTP_URL_STRIP_PASS', 16); // Strip any password authentication information
define('HTTP_URL_STRIP_AUTH', 32); // Strip any authentication information
define('HTTP_URL_STRIP_PORT', 64); // Strip explicit port numbers
define('HTTP_URL_STRIP_PATH', 128); // Strip complete path
define('HTTP_URL_STRIP_QUERY', 256); // Strip query string
define('HTTP_URL_STRIP_FRAGMENT', 512); // Strip any fragments (#identifier)
define('HTTP_URL_STRIP_ALL', 1024); // Strip anything but scheme and host
// Build an URL
// The parts of the second URL will be merged into the first according to the flags argument.
//
// #param mixed (Part(s) of) an URL in form of a string or associative array like parse_url() returns
// #param mixed Same as the first argument
// #param int A bitmask of binary or'ed HTTP_URL constants (Optional)HTTP_URL_REPLACE is the default
// #param array If set, it will be filled with the parts of the composed url like parse_url() would return
function http_build_url($url, $parts = array (), $flags = HTTP_URL_REPLACE, &$new_url = false) {
$keys = array (
'user',
'pass',
'port',
'path',
'query',
'fragment'
);
// HTTP_URL_STRIP_ALL becomes all the HTTP_URL_STRIP_Xs
if ($flags & HTTP_URL_STRIP_ALL) {
$flags |= HTTP_URL_STRIP_USER;
$flags |= HTTP_URL_STRIP_PASS;
$flags |= HTTP_URL_STRIP_PORT;
$flags |= HTTP_URL_STRIP_PATH;
$flags |= HTTP_URL_STRIP_QUERY;
$flags |= HTTP_URL_STRIP_FRAGMENT;
}
// HTTP_URL_STRIP_AUTH becomes HTTP_URL_STRIP_USER and HTTP_URL_STRIP_PASS
else if ($flags & HTTP_URL_STRIP_AUTH) {
$flags |= HTTP_URL_STRIP_USER;
$flags |= HTTP_URL_STRIP_PASS;
}
// Parse the original URL
$parse_url = parse_url($url);
// Scheme and Host are always replaced
if (isset($parts['scheme']))
$parse_url['scheme'] = $parts['scheme'];
if (isset($parts['host']))
$parse_url['host'] = $parts['host'];
// (If applicable) Replace the original URL with it's new parts
if ($flags & HTTP_URL_REPLACE) {
foreach ($keys as $key) {
if (isset($parts[$key]))
$parse_url[$key] = $parts[$key];
}
} else {
// Join the original URL path with the new path
if (isset($parts['path']) && ($flags & HTTP_URL_JOIN_PATH)) {
if (isset($parse_url['path']))
$parse_url['path'] = rtrim(str_replace(basename($parse_url['path']), '', $parse_url['path']), '/') . '/' . ltrim($parts['path'], '/');
else
$parse_url['path'] = $parts['path'];
}
// Join the original query string with the new query string
if (isset($parts['query']) && ($flags & HTTP_URL_JOIN_QUERY)) {
if (isset($parse_url['query']))
$parse_url['query'] .= '&' . $parts['query'];
else
$parse_url['query'] = $parts['query'];
}
}
// Strips all the applicable sections of the URL
// Note: Scheme and Host are never stripped
foreach ($keys as $key) {
if ($flags & (int)constant('HTTP_URL_STRIP_' . strtoupper($key)))
unset($parse_url[$key]);
}
$new_url = $parse_url;
return ((isset($parse_url['scheme'])) ? $parse_url['scheme'] . '://' : '') . ((isset($parse_url['user'])) ? $parse_url['user'] . ((isset($parse_url['pass'])) ? ':' . $parse_url['pass'] : '') . '#' : '')
. ((isset($parse_url['host'])) ? $parse_url['host'] : '') . ((isset($parse_url['port'])) ? ':' . $parse_url['port'] : '') . ((isset($parse_url['path'])) ? $parse_url['path'] : '')
. ((isset($parse_url['query'])) ? '?' . $parse_url['query'] : '') . ((isset($parse_url['fragment'])) ? '#' . $parse_url['fragment'] : '');
}

Answer 2

Take a look at http://php.net/manual/en/function.parse-url.php and http://www.php.net/manual/en/function.http-build-url.php.
Now you can do something like this:
<?php
$return10 = '... some url here ...';
$newUrl = http_build_url(
$return10,
array('query' => 'var2=example'),
HTTP_URL_JOIN_QUERY
);
?>

Answer 3

You can construct the URI seperately:
if(!strpos($uri, "?"))
$uri .= "&var2=example"
else
$uri .= "?var2=example"
header("Location: $uri");