PrestaShop backend, Fatal error in ajax call

On the backend of a PrestaShop site I'm using this function:

public function hookAjax($action, $id_product, $id_lang, $title, $descript, $order, $id = NULL)

    /* various code*/

            'block_define'  => $this->getFormDesc($id_product)
    return $this->context->smarty->fetch($this->local_path.'views/templates/hook/admin_extra_desc.tpl');

public function getFormDesc($id_product) {
    $array = array();

    foreach (Language::getLanguages() as $lang) {
        /*various code*/

        foreach($result as $k=> $r) {
            $files   = array();
            $helper = new HelperImageUploader();
            $result[$k]['img-form'] = $helper->render();
            $result[$k]['img'] = $result[$k]['img'] ? _PS_BASE_URL_.__PS_BASE_URI__.'modules/module-name/upload/'.$result[$k]['img'] : '';

        $array[$lang["id_lang"]] = array(
            'lang_data'     =>  $lang,
            'count'         =>  count($result),
            'data'          =>  $result

    return $array;


HookAjax is called by:


    $context = Context::getContext();
    $addDesc = Module::getInstanceByName('module-name');

    echo $addDesc->hookAjax($_POST['action'],$_POST['id_prodotto'],$_POST['lang'],$_POST['title'], $_POST['text_desc'], NULL, $_POST['row']);


But I struggle with this error:

Fatal error: Call to a member function addJs() on a non-object in {my_site}/classes/helper/HelperUploader.php on line 257


You need to include init.php in HookAjax after including so that controller is initialized in context.


Note that this is just bad practice, respect the MVC and use proper controllers for your AJAX calls and data validation/processing in them, not inside main module class.


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