PHP function to build query string from array - php

Question

I'm looking for the name of the PHP function to build a query string from an array of key value pairs. Please note, I am looking for the built in PHP function to do this, not a homebrew one (that's all a google search seems to return). There is one, I just can't remember its name or find it on php.net. IIRC its name isn't that intuitive.

Answer 1

You're looking for http_build_query().

Answer 2

Here's a simple php4-friendly implementation:
/**
* Builds an http query string.
* #param array $query // of key value pairs to be used in the query
* #return string // http query string.
**/
function build_http_query( $query ){
$query_array = array();
foreach( $query as $key => $key_value ){
$query_array[] = urlencode( $key ) . '=' . urlencode( $key_value );
}
return implode( '&', $query_array );
}

Answer 3

Just as addition to #thatjuan's answer.
More compatible PHP4 version of this:
if (!function_exists('http_build_query')) {
if (!defined('PHP_QUERY_RFC1738')) {
define('PHP_QUERY_RFC1738', 1);
}
if (!defined('PHP_QUERY_RFC3986')) {
define('PHP_QUERY_RFC3986', 2);
}
function http_build_query($query_data, $numeric_prefix = '', $arg_separator = '&', $enc_type = PHP_QUERY_RFC1738)
{
$data = array();
foreach ($query_data as $key => $value) {
if (is_numeric($key)) {
$key = $numeric_prefix . $key;
}
if (is_scalar($value)) {
$k = $enc_type == PHP_QUERY_RFC3986 ? urlencode($key) : rawurlencode($key);
$v = $enc_type == PHP_QUERY_RFC3986 ? urlencode($value) : rawurlencode($value);
$data[] = "$k=$v";
} else {
foreach ($value as $sub_k => $val) {
$k = "$key[$sub_k]";
$k = $enc_type == PHP_QUERY_RFC3986 ? urlencode($k) : rawurlencode($k);
$v = $enc_type == PHP_QUERY_RFC3986 ? urlencode($val) : rawurlencode($val);
$data[] = "$k=$v";
}
}
}
return implode($arg_separator, $data);
}
}

Answer 4

Implode will combine an array into a string for you, but to make an SQL query out a kay/value pair you'll have to write your own function.