How to combine query strings in PHP - php

Question

Given a url, and a query string, how can I get the url resulting from the combination of the query string with the url?
I'm looking for functionality similar to .htaccess's qsa. I realize this would be fairly trivial to implement completely by hand, however are there built-in functions that deal with query strings which could either simplify or completely solve this?
Example input/result sets:
Url="http://www.example.com/index.php/page?a=1"
QS ="?b=2"
Result="http://www.example.com/index.php/page?a=1&b=2"
-
Url="page.php"
QS ="?b=2"
Result="page.php?b=2"

Answer 1

How about something that uses no PECL extensions and isn't a huge set of copied-and-pasted functions? It's still a tad complex because you're splicing together two query strings and want to do it in a way that isn't just $old .= $new;
We'll use parse_url to extract the query string from the desired url, parse_str to parse the query strings you wish to join, array_merge to join them together, and http_build_query to create the new, combined string for us.
// Parse the URL into components
$url = 'http://...';
$url_parsed = parse_url($url);
$new_qs_parsed = array();
// Grab our first query string
parse_str($url_parsed['query'], $new_qs_parsed);
// Here's the other query string
$other_query_string = 'that=this&those=these';
$other_qs_parsed = array();
parse_str($other_query_string, $other_qs_parsed);
// Stitch the two query strings together
$final_query_string_array = array_merge($new_qs_parsed, $other_qs_parsed);
$final_query_string = http_build_query($final_query_string_array);
// Now, our final URL:
$new_url = $url_parsed['scheme']
. '://'
. $url_parsed['host']
. $url_parsed['path']
. '?'
. $final_query_string;

Answer 2

You can get the query string part from url using:
$_SERVER['QUERY_STRING']
and then append it to url normally.
If you want to specify your own custom variables in query string, have a look at:
http_build_query

Answer 3

This is a series of functions taken from the WordPress "framework" that will do it, but this could quite well be too much:
add_query_arg()
/**
* Retrieve a modified URL query string.
*
* You can rebuild the URL and append a new query variable to the URL query by
* using this function. You can also retrieve the full URL with query data.
*
* Adding a single key & value or an associative array. Setting a key value to
* emptystring removes the key. Omitting oldquery_or_uri uses the $_SERVER
* value.
*
* #since 1.0
*
* #param mixed $param1 Either newkey or an associative_array
* #param mixed $param2 Either newvalue or oldquery or uri
* #param mixed $param3 Optional. Old query or uri
* #return string New URL query string.
*/
public function add_query_arg() {
$ret = '';
if ( is_array( func_get_arg(0) ) ) {
$uri = ( #func_num_args() < 2 || false === #func_get_arg( 1 ) ) ? $_SERVER['REQUEST_URI'] : #func_get_arg( 1 );
} else {
$uri = ( #func_num_args() < 3 || false === #func_get_arg( 2 ) ) ? $_SERVER['REQUEST_URI'] : #func_get_arg( 2 );
}
if ( $frag = strstr( $uri, '#' ) ) {
$uri = substr( $uri, 0, -strlen( $frag ) );
} else {
$frag = '';
}
if ( preg_match( '|^https?://|i', $uri, $matches ) ) {
$protocol = $matches[0];
$uri = substr( $uri, strlen( $protocol ) );
} else {
$protocol = '';
}
if ( strpos( $uri, '?' ) !== false ) {
$parts = explode( '?', $uri, 2 );
if ( 1 == count( $parts ) ) {
$base = '?';
$query = $parts[0];
} else {
$base = $parts[0] . '?';
$query = $parts[1];
}
} elseif ( !empty( $protocol ) || strpos( $uri, '=' ) === false ) {
$base = $uri . '?';
$query = '';
} else {
$base = '';
$query = $uri;
}
parse_str( $query, $qs );
if ( get_magic_quotes_gpc() )
$qs = format::stripslashes_deep( $qs );
$qs = format::urlencode_deep( $qs ); // this re-URL-encodes things that were already in the query string
if ( is_array( func_get_arg( 0 ) ) ) {
$kayvees = func_get_arg( 0 );
$qs = array_merge( $qs, $kayvees );
} else {
$qs[func_get_arg( 0 )] = func_get_arg( 1 );
}
foreach ( ( array ) $qs as $k => $v ) {
if ( $v === false )
unset( $qs[$k] );
}
$ret = http_build_query( $qs, '', '&' );
$ret = trim( $ret, '?' );
$ret = preg_replace( '#=(&|$)#', '$1', $ret );
$ret = $protocol . $base . $ret . $frag;
$ret = rtrim( $ret, '?' );
return $ret;
}
stripslashes_deep()
/**
* Navigates through an array and removes slashes from the values.
*
* If an array is passed, the array_map() function causes a callback to pass the
* value back to the function. The slashes from this value will removed.
*
* #since 1.0
*
* #param array|string $value The array or string to be stripped
* #return array|string Stripped array (or string in the callback).
*/
function stripslashes_deep( $value ) {
return is_array( $value ) ? array_map( array('self', 'stripslashes_deep'), $value ) : stripslashes( $value );
}
urlencode_deep()
/**
* Navigates through an array and encodes the values to be used in a URL.
*
* Uses a callback to pass the value of the array back to the function as a
* string.
*
* #since 1.0
*
* #param array|string $value The array or string to be encoded.
* #return array|string $value The encoded array (or string from the callback).
*/
public function urlencode_deep( $value ) {
return is_array($value) ? array_map( array('self', 'urlencode_deep'), $value) : urlencode($value);
}

Answer 4

THere is no built-in function to do this. However, you can use this function from http PECL extension,
http://usphp.com/manual/en/function.http-build-url.php
For example,
$url = http_build_url("http://www.example.com/index.php/page?a=1",
array(
"b" => "2"
)
);

Answer 5

So what happens if the urls conflict? If both urls contain a b= component in the querystring? You'd need to decided which holds sway.
Here's a chunk of code that does what you want, parsing each string as a url, then extracting the query url part and implode() ing them back together.
$url="http://www.example.com/index.php/page?a=1";
$qs ="?b=2";
$url_parsed = parse_url($url);
$qs_parsed = parse_url($qs);
$args = array(
$url_parsed['query'],
$qs_parsed['query'],
);
$new_url = $url_parsed['scheme'];
$new_url .= '://';
$new_url .= $url_parsed['host'];
$new_url .= $url_parsed['path'];
$new_url .= '?';
$new_url .= implode('&', $args);
print $new_url;