PHP: Get the full query string.
This is a tutorial on how to get the FULL query string as a string using PHP.
Most people are aware of how to retrieve URL parameters using the $_GET array. However, what if you wanted to retrieve these parameters as a string?
Let’s say, for example, that we have the following URL:
test.com/file.php?id=299&mobile=Y&clid=392829
As you can see, the query string in the URL above contains three GET parameters.
If we want to retrieve everything after the question mark and assign it to a string, we can simply access the QUERY_STRING element in the $_SERVER superglobal array like so:
//Get the full string $queryString = $_SERVER['QUERY_STRING']; var_dump($queryString);
If we were to run our code snippet above on the URL in question, it would return the following string:
Note how this string does not contain the question mark symbol. If this symbol is needed, then you will need to re-add it yourself.
What if there is no query string?
If there is no query string, then the QUERY_STRING key in $_SERVER will be an empty string.
Unlike other elements in the $_SERVER array, QUERY_STRING should always exist.
Why is this useful?
This can be useful for a number of reasons.
The first two that spring to mind are:
QUERY_STRING and XSS.
You should never print the QUERY_STRING variable out onto the page without filtering it first.
If you do this, you will leave yourself open to the possibility of a Cross Site Scripting (XSS) attack.
The code above is vulnerable to XSS because the QUERY_STRING result is being printed out without any sort of filtering. As a result, malicious users could potentially put JavaScript code into the query string and have it executed on your page.
To be safe, you should wrap it in the htmlentities function like so:
Hopefully, you found this guide useful!
http_build_query
Generates a URL-encoded query string from the associative (or indexed) array provided.
Parameters
May be an array or object containing properties.
If data is an array, it may be a simple one-dimensional structure, or an array of arrays (which in turn may contain other arrays).
If data is an object, then only public properties will be incorporated into the result.
If numeric indices are used in the base array and this parameter is provided, it will be prepended to the numeric index for elements in the base array only.
This is meant to allow for legal variable names when the data is decoded by PHP or another CGI application later on.
The argument separator. If not set or null , arg_separator.output is used to separate arguments.
By default, PHP_QUERY_RFC1738 .
If encoding_type is PHP_QUERY_RFC1738 , then encoding is performed per » RFC 1738 and the application/x-www-form-urlencoded media type, which implies that spaces are encoded as plus ( + ) signs.
If encoding_type is PHP_QUERY_RFC3986 , then encoding is performed according to » RFC 3986, and spaces will be percent encoded ( %20 ).
Return Values
Returns a URL-encoded string.
Changelog
Examples
Example #1 Simple usage of http_build_query()
$data = array(
‘foo’ => ‘bar’ ,
‘baz’ => ‘boom’ ,
‘cow’ => ‘milk’ ,
‘null’ => null ,
‘php’ => ‘hypertext processor’
);
echo http_build_query ( $data ) . «\n» ;
echo http_build_query ( $data , » , ‘&’ );
The above example will output:
foo=bar&baz=boom&cow=milk&php=hypertext+processor foo=bar&baz=boom&cow=milk&php=hypertext+processor
Example #2 http_build_query() with numerically index elements.
$data = array( ‘foo’ , ‘bar’ , ‘baz’ , null , ‘boom’ , ‘cow’ => ‘milk’ , ‘php’ => ‘hypertext processor’ );
echo http_build_query ( $data ) . «\n» ;
echo http_build_query ( $data , ‘myvar_’ );
?>
The above example will output:
0=foo&1=bar&2=baz&4=boom&cow=milk&php=hypertext+processor myvar_0=foo&myvar_1=bar&myvar_2=baz&myvar_4=boom&cow=milk&php=hypertext+processor
Example #3 http_build_query() with complex arrays
$data = array(
‘user’ => array(
‘name’ => ‘Bob Smith’ ,
‘age’ => 47 ,
‘sex’ => ‘M’ ,
‘dob’ => ‘5/12/1956’
),
‘pastimes’ => array( ‘golf’ , ‘opera’ , ‘poker’ , ‘rap’ ),
‘children’ => array(
‘bobby’ => array( ‘age’ => 12 , ‘sex’ => ‘M’ ),
‘sally’ => array( ‘age’ => 8 , ‘sex’ => ‘F’ )
),
‘CEO’
);
echo http_build_query ( $data , ‘flags_’ );
?>
The above example will output: (word wrapped for readability)
user%5Bname%5D=Bob+Smith&user%5Bage%5D=47&user%5Bsex%5D=M& user%5Bdob%5D=5%2F12%2F1956&pastimes%5B0%5D=golf&pastimes%5B1%5D=opera& pastimes%5B2%5D=poker&pastimes%5B3%5D=rap&children%5Bbobby%5D%5Bage%5D=12& children%5Bbobby%5D%5Bsex%5D=M&children%5Bsally%5D%5Bage%5D=8& children%5Bsally%5D%5Bsex%5D=F&flags_0=CEO
Note:
Only the numerically indexed element in the base array «CEO» received a prefix. The other numeric indices, found under pastimes, do not require a string prefix to be legal variable names.
Example #4 Using http_build_query() with an object
class parentClass public $pub = ‘publicParent’ ;
protected $prot = ‘protectedParent’ ;
private $priv = ‘privateParent’ ;
public $pub_bar = null ;
protected $prot_bar = null ;
private $priv_bar = null ;
public function __construct () $this -> pub_bar = new childClass ();
$this -> prot_bar = new childClass ();
$this -> priv_bar = new childClass ();
>
>
class childClass public $pub = ‘publicChild’ ;
protected $prot = ‘protectedChild’ ;
private $priv = ‘privateChild’ ;
>
echo http_build_query ( $parent );
?>
The above example will output:
pub=publicParent&pub_bar%5Bpub%5D=publicChild
See Also
- parse_str() — Parses the string into variables
- parse_url() — Parse a URL and return its components
- urlencode() — URL-encodes string
- array_walk() — Apply a user supplied function to every member of an array
User Contributed Notes 24 notes
Params with null value do not present in result string.
$arr = array( ‘test’ => null , ‘test2’ => 1 );
echo http_build_query ( $arr );
?>
will produce:
Number to string conversion occured in is affected by locale settings, which might not be obvious.
setlocale ( LC_ALL , ‘us_En’ );
http_build_query ( $params ) // v=5.63
setlocale ( LC_ALL , ‘ru_RU’ );
http_build_query ( $params ) // v=5,63 mind the comma
?>
Passing null to $arg_separator is the same as passing an empty string, which is probably not what you want.
If you need to change the enc_type, use this:
http_build_query($query, null, ini_get(‘arg_separator.output’), PHP_QUERY_RFC3986);
// BAD CODE!
http_build_query($query, null, null, PHP_QUERY_RFC3986);
if you send boolean values it transform in integer :
$a = [teste1= true,teste2=false];
echo http_build_query($a)
//result will be teste1=1&teste2=0
This function makes like this
$query = http_build_query($query);
$query = preg_replace(‘/%5B4+%5D/simU’, ‘%5B%5D’, $query);
As noted before, with php5.3 the separator is & on some servers it seems. Normally if posting to another php5.3 machine this will not be a problem.
But if you post to a tomcat java server or something else the & might not be handled properly.
http_build_query($array); //gives & to some servers
If you need the inverse functionality, and (like me) you cannot use pecl_http, you may want to use something akin to the following.
// mimic the behavior of $_GET, see also RFC 1738 and 3986.
$Delimiter = ini_get ( ‘arg_separator.input’ );
$Params = array();
if (!empty( $NameValueParts [ ‘indices_present’ ])) $Indices = explode ( ‘][‘ , $NameValueParts [ ‘indices’ ]);
foreach ( $Indices as $Index ) if (! is_array ( $Param )) $Param = array();
>
if ( $Index === » ) $Param [] = array();
end ( $Param );
$Param =& $Param [ key ( $Param )];
> else if ( ctype_digit ( $Index ))
if (! array_key_exists ( $Index , $Param )) $Param [ $Index ] = array();
>
$Param =& $Param [ $Index ];
>
>
>
if (!empty( $NameValueParts [ ‘value_present’ ])) $Param = urldecode ( $NameValueParts [ ‘value’ ]);
> else $Param = » ;
>
>
>
Is it worth noting that if query_data is an associative array and a value is itself an empty array, or an array of nothing but empty array (or arrays containing only empty arrays etc.), the corresponding key will not appear in the resulting query string?
E.g.
$post_data = array(‘name’=>’miller’, ‘address’=>array(‘address_lines’=>array()), ‘age’=>23);
echo http_build_query($post_data);
When using the http_build_query function to create a URL query from an array for use in something like curl_setopt($ch, CURLOPT_POSTFIELDS, $post_url), be careful about the url encoding.
In my case, I simply wanted to pass on the received $_POST data to a CURL’s POST data, which requires it to be in the URL format. If something like a space [ ] goes into the http_build_query, it comes out as a +. If you’re then sending this off for POST again, you won’t get the expected result. This is good for GET but not POST.
Instead you can make your own simple function if you simply want to pass along the data:
$post_url = » ;
foreach ( $_POST AS $key => $value )
$post_url .= $key . ‘=’ . $value . ‘&’ ;
$post_url = rtrim ( $post_url , ‘&’ );
?>
You can then use this to pass along POST data in CURL.
$ch = curl_init ( $some_url );
curl_setopt ( $ch , CURLOPT_POST , true );
curl_setopt ( $ch , CURLOPT_POSTFIELDS , $post_url );
curl_exec ( $ch );
?>
Note that at the final page that processes the POST data, you should be properly filtering/escaping it.
As noted, this function omits keys with null values. This could break some code which treats the key as boolean, and so has no value, or other code expecting the array to be populated regardless of value.
A workaround for this is to replace the null values with an empty string:
// Compensate for fact that http_build_query omits null values
foreach($data as &$datum) if($datum===null) $datum=»;
Losing the null-ness of the original is no real loss if it’s supposed to be a real query string. If the null is important, you could use a dummy value instead.
Be careful about Example 1 — it is exactly how *not* to implement things.
You should HTML encode your URL if embedding it in a web page. This is more involved than just replacing & with &. Doing as this example suggests is a security hole waiting to happen.
Correct implementation of coding the array of params without indexes (valdikks fixed code — didnt work for inner arrays):
I noticed that even with the magic quotes disabled, http_build_query() automagically adds slashes to strings.
So, I had to add «stripslashes» to every string variable.
on my install of PHP 5.3, http_build_query() seems to use & as the default separator. Kind of interesting when combined with stream_context_create() for a POST request, and getting $_POST[‘amp;fieldName’] on the receiving end.
When using http_build_query($args) where $args is an array; note that there is a limit to the size of array. See max_input_vars in your php.ini to increase this size.