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http_build_query

PHP function Edit on GitHub ✎

(PHP 5, PHP 7, PHP 8)

Generate URL-encoded query string

Description

http_build_query(array|object $data, string $numeric_prefix = "", string|null $arg_separator = null, int $encoding_type = PHP_QUERY_RFC1738): string

Generates a URL-encoded query string from the associative (or indexed) array provided.

Parameters

data

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.

Note

The __toString() magic method is not called when an object is evaluated. To use the string representation of an object in the query string, the object must be explicitly cast to a string.

numeric_prefix

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.

arg_separator

The argument separator. If not set or null, arg_separator.output is used to separate arguments.

encoding_type

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

VersionDescription
8.4.0Prior to PHP 8.4.0, BackedEnum properties of data were converted to objects, rather than their scalar equivalents.
8.0.0arg_separator is now nullable.

Examples

Simple usage of http_build_query()

php
<?php
$data = array(
    'foo' => 'bar',
    'baz' => 'boom',
    'cow' => 'milk',
    'null' => null,
    'php' => 'hypertext processor'
);

echo http_build_query($data) . "\n";
echo http_build_query($data, '', '&amp;');

?>

The above example will output:

output
foo=bar&baz=boom&cow=milk&php=hypertext+processor
foo=bar&amp;baz=boom&amp;cow=milk&amp;php=hypertext+processor

http_build_query() with numerically index elements.

php
<?php
$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:

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

http_build_query() with complex arrays

php
<?php
$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)

output
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.

Using http_build_query() with an object

php
<?php
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';
}

$parent = new parentClass();

echo http_build_query($parent);
?>

The above example will output:

output
pub=publicParent&pub_bar%5Bpub%5D=publicChild

Using http_build_query() with objects containing __toString()

php
<?php
class Foo {
    public $publicProperty = 'visible';

    public function __toString() {
        return "bar";
    }
}

$params = array(
    'a' => 'b',
    'foo' => new Foo()
);

// Without casting, http_build_query reads the public properties
echo http_build_query($params) . "\n";

// With explicit casting, http_build_query uses the __toString() output
$params['foo'] = (string) new Foo();
echo http_build_query($params) . "\n";
?>

The above example will output:

output
a=b&foo%5BpublicProperty%5D=visible
a=b&foo=bar

See Also

Source: reference/url/functions/http-build-query.xml · from the official PHP manual (php/doc-en)