PHP function to build query string from array

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

but for inverse this work, you can use :

void parse_str(str $input, array $output);
//for example:
$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz

parse_str($str, $output);
echo $output['first'];  // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz

Good luck.

Answer 5

As this question is quite old and for PHP, here is a way to do it in the (currently) very popular PHP framework Laravel.

To encode the query string for a path in your application, give your routes names and then use the route() helper function like so:

route('documents.list.', ['foo' => 'bar']);

The result will look something like:

http://localhost/documents/list?foo=bar

Also be aware that if your route has any path segment parameters e.g. /documents/{id}, then make sure you pass an id argument to the route() parameters too, otherwise it will default to using the value of the first parameter.

Answer 6

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.