Grocery Crud default value after add - codeigniter

Question

I need to add default images to post, if user do not select an image to upload.
Field to load the image optional.
How can i make it?
I use this controller.
public function news() {
$cur_user_id['user_id'] = $this->ion_auth->user()->row()->user_id;
$this->db->update('news', $cur_user_id);
$crud = new grocery_CRUD();
$crud->set_table('news')
->display_as('title', 'Заголовок')
->display_as('content', 'Текст')
->display_as('date', 'Дата')
->display_as('urlpict', 'Изображение')
->display_as('hide', 'Отображение')
->display_as('tags', 'Теги')
->display_as('add_new_tags', 'Добавить новые теги')
->display_as('menu_id', 'Раздел меню');
$crud->unset_columns('user_id');
$crud->required_fields('title', 'content', 'date', 'hide');
//relation
$crud->set_relation('menu_id', 'my_menu', 'name');
$crud->set_relation_n_n('tags', 'tag2art', 'tags', 'art_id', 'tag_id', 'tag');
//configuration for uploading
$this->config->set_item('grocery_crud_file_upload_allow_file_types', 'gif|jpeg|jpg|png');
$crud->set_field_upload('urlpict', 'assets/uploads/images');
//callback function
$crud->callback_after_upload(array($this, 'func_callback_after_upload'));
$state = $crud->getState();
$state_info = $crud->getStateInfo();
if ($state == 'add') {
$crud->fields('title', 'content', 'date', 'urlpict', 'hide', 'tags', 'add_new_tags', 'menu_id');
$crud->callback_add_field('add_new_tags', array($this, 'add_field_callback_1'));
} else {
$crud->unset_fields('add_new_tags', 'views', 'user_id');
}
$output = $crud->render();
$this->load->view('administrator/news', $output);
}
It's my callback_function
function func_callback_after_upload($uploader_response, $field_info, $files_to_upload)
{
$config['image_library'] = 'gd2';
$config['source_image'] = $field_info->upload_path . '/' . $uploader_response[0]->name;
$config['create_thumb'] = FALSE;
$config['maintain_ratio'] = TRUE;
$config['width'] = 175;
$config['height'] = 175;
$this->load->library('image_lib', $config);
$this->image_lib->resize();
return true;
}

Answer 1

Mine solution
Instead $crud->callback_after_update(array($this, 'default_img'));
I used $crud->callback_after_insert(array($this, 'default_img'));
And my controller
function default_img($post_array, $primary_key) {
if (!$this->input->post('urlpict')) {
$default_img = array(
"id" => $primary_key,
"urlpict" => "news_default.png"
);
$this->db->update('news', $default_img, array('id' => $primary_key));
return true;
}
}