public function addRecipeSteps(RecipeSteps $step)
 {
     $numStep = $this->countRecipeStepss();
     $step->setorder($numStep);
     parent::addRecipeSteps($step);
 }
<?php

session_start();
require_once '../../../bootstrap.php';
require '../../../services/UserService.php';
require '../../../services/ItemService.php';
UserService::withRole(UserService::$CONTRIBUTOR, function () {
    $step = new RecipeSteps();
    $step->setdescription($_POST["description"]);
    $recipeId = $_GET["recipeId"];
    $recipe = RecipeQuery::create()->findPk($recipeId);
    if (isset($recipe)) {
        $recipe->addRecipeSteps($step);
        $saved = ItemService::saveWithValidation($recipe, 200);
        if ($saved == true) {
            $id = $step->getId();
            $result = array("id" => $id);
            echo json_encode($result);
        }
    } else {
        http_response_code(404);
    }
});