add_query_arg( $args )

Retrieves a modified URL query string.

Description

You can rebuild the URL and append query variables to the URL query by using this function.
There are two ways to use this function; either a single key and value, or an associative array.

Using a single key and value:

add_query_arg( 'key', 'value', 'http://example.com' );

Using an associative array:

add_query_arg( array(
    'key1' => 'value1',
    'key2' => 'value2',
), 'http://example.com' );

Omitting the URL from either use results in the current URL being used (the value of $_SERVER['REQUEST_URI']).

Values are expected to be encoded appropriately with urlencode() or rawurlencode().

Setting any query variable’s value to boolean false removes the key (see remove_query_arg()).

Important: The return value of add_query_arg() is not escaped by default. Output should be late-escaped with esc_url() or similar to help prevent vulnerability to cross-site scripting (XSS) attacks.

Parameters

$key: (Required) Either a query variable key, or an associative array of query variables.
$value: (Optional) Either a query variable value, or a URL to act upon.
$url: (Optional) A URL to act upon.

Return

(string) New URL query string (unescaped).

Source

File: wp-includes/functions.php

function add_query_arg() {
	$args = func_get_args();
	if ( is_array( $args[0] ) ) {
		if ( count( $args ) < 2 || false === $args[1] )
			$uri = $_SERVER['REQUEST_URI'];
		else
			$uri = $args[1];
	} else {
		if ( count( $args ) < 3 || false === $args[2] )
			$uri = $_SERVER['REQUEST_URI'];
		else
			$uri = $args[2];
	}

	if ( $frag = strstr( $uri, '#' ) )
		$uri = substr( $uri, 0, -strlen( $frag ) );
	else
		$frag = '';

	if ( 0 === stripos( $uri, 'http://' ) ) {
		$protocol = 'http://';
		$uri = substr( $uri, 7 );
	} elseif ( 0 === stripos( $uri, 'https://' ) ) {
		$protocol = 'https://';
		$uri = substr( $uri, 8 );
	} else {
		$protocol = '';
	}

	if ( strpos( $uri, '?' ) !== false ) {
		list( $base, $query ) = explode( '?', $uri, 2 );
		$base .= '?';
	} elseif ( $protocol || strpos( $uri, '=' ) === false ) {
		$base = $uri . '?';
		$query = '';
	} else {
		$base = '';
		$query = $uri;
	}

	wp_parse_str( $query, $qs );
	$qs = urlencode_deep( $qs ); // this re-URL-encodes things that were already in the query string
	if ( is_array( $args[0] ) ) {
		foreach ( $args[0] as $k => $v ) {
			$qs[ $k ] = $v;
		}
	} else {
		$qs[ $args[0] ] = $args[1];
	}

	foreach ( $qs as $k => $v ) {
		if ( $v === false )
			unset( $qs[$k] );
	}

	$ret = build_query( $qs );
	$ret = trim( $ret, '?' );
	$ret = preg_replace( '#=(&|$)#', '$1', $ret );
	$ret = $protocol . $base . $ret . $frag;
	$ret = rtrim( $ret, '?' );
	return $ret;
}

Expand Source Code View on GitHub

Changelog

Changelog
Version	Description
5.3.0	Formalized the existing and already documented parameters by adding `...$args` to the function signature.
1.5.0	Introduced.