var data = {}
data.action = 'create';
data.assure = {
        id :        12,
        nom :       10
        }
data.courtier = {
        id :        12,
        nom :       "toto",
        agence :    { id :  6, nom : "abc"}
        }

$args['action'] = array(
    'filter'    => FILTER_VALIDATE_REGEXP,
    'flags'     => FILTER_REQUIRE_SCALAR,
    'options'   => array('regexp' => "/^(create|update|delete)$/")
    );
$args['assure'] = array(
    'filter' => FILTER_SANITIZE_STRING,
    'flags'  => FILTER_REQUIRE_ARRAY,
    );
$args['courtier'] = array(
    'filter' => FILTER_SANITIZE_STRING,
    'flags'  => FILTER_REQUIRE_ARRAY,
    );
$args['courtier']['id'] = array(
    'filter' => FILTER_VALIDATE_INT,
    'flags'  => FILTER_REQUIRE_SCALAR,
    );
$args['courtier']['nom'] = array(
    'filter' => FILTER_VALIDATE_INT,
    'flags'  => FILTER_REQUIRE_SCALAR,
    );
$args['courtier']['agence'] = array(
    'filter' => FILTER_SANITIZE_STRING,
    'flags'  => FILTER_REQUIRE_ARRAY,
    );
$args['courtier']['agence']['id'] = array(
    'filter' => FILTER_VALIDATE_INT,
    'flags'  => FILTER_REQUIRE_SCALAR,
    );
$args['courtier']['agence']['nom'] = array(
    'filter' => FILTER_VALIDATE_INT,
    'flags'  => FILTER_REQUIRE_SCALAR,
    );

$myinputs = filter_input_array(INPUT_POST, $args);
print_r($myinputs);

Array
(
[id] =>
[action] => create
[assure] => Array
    (
        [id] => 12
        [nom] => 10
    )

[courtier] => Array
    (
        [id] => 12
        [nom] => toto
        [agence] => Array
            (
                [id] => 6
                [nom] => abc
            )

    )
)