http_build_query ignores the key if the value is an empty array. How is this not a bug?

Question

I ran into a problem today where I was passing a key with the value set to an empty array to http_build_query(). E.g.:

$args = array(\"foo\", \"bar\         


        

Answer 1

I've reimplemented http_build_query to leave empty objects/arrays in the returned query string (suffixed by an '=' symbol). I've enhanced it a bit from the default functionality as well, so all-in-all:

• Maintains empty objects and arrays
• Changed the default enc_type to RFC3986 (relevant to the ages)
• Added a key-value separator argument (ability to override the default '=')
• Removes numeric indices for numerically-indexed key-value pairs

I have not tested this in a production environment (no idea about performance or bugs), and it is not optimized, but very well spelled out.

function buildQuery($input,$numeric_prefix='',
        $arg_separator='&',$enc_type=2,
        $keyvalue_separator='=',$prefix='') {
    if ( is_array($input) ) {
        $arr = array();
        foreach ( $input as $key => $value ) {
            $name = $prefix;
            if ( strlen($prefix) ) {
                $name .= '[';
                if ( !is_numeric($key) ) {
                    $name .= $key;
                }
                $name .= ']';
            } else {
                if ( is_numeric($key) ) {
                    $name .= $numeric_prefix;
                }
                $name .= $key;
            }
            if ( (is_array($value) || is_object($value)) && count($value) ) {
                $arr[] = buildQuery($value,$numeric_prefix,
                        $arg_separator,$enc_type,
                        $keyvalue_separator,$name);
            } else {
                if ( $enc_type === 2 ) {
                    $arr[] = rawurlencode($name)
                        .$keyvalue_separator
                        .rawurlencode($value?:'');
                } else {
                    $arr[] = urlencode($name)
                        .$keyvalue_separator
                        .urlencode($value?:'');
                }
            }
        }
        return implode($arg_separator,$arr);
    } else {
        if ( $enc_type === 2 ) {
            return rawurlencode($input);
        } else {
            return urlencode($input);
        }
    }
}

Example:

$arr = array(
        'hello' => 'world',
        'colors' => array('red','green','blue'),
        'emptyArr' => array(),
        'nested' => array(
            'empty' => array(),
            'fruits' => array('orange','banana','apple'),
            'curly' => 'sue',
            'assoc' => array('a'=>'alpha','b'=>'bravo','c'=>'charlie')
        )
    );

echo buildQuery($arr);

Outputs: hello=world&colors%5B%5D=red&colors%5B%5D=green&colors%5B%5D=blue&emptyArr=&nested%5Bempty%5D=&nested%5Bfruits%5D%5B%5D=orange&nested%5Bfruits%5D%5B%5D=banana&nested%5Bfruits%5D%5B%5D=apple&nested%5Bcurly%5D=sue&nested%5Bassoc%5D%5Ba%5D=alpha&nested%5Bassoc%5D%5Bb%5D=bravo&nested%5Bassoc%5D%5Bc%5D=charlie I hope this finds someone well.