Get the page ID if the page content has a shortcode

I have been trying to get the page ID of which it contains shortcode. I 'm getting null. Not sure what I'm doing wrong.

function availabilty_id() {
  global $template_id;
  // Custom Query to look only in pages post type
  $template_query = new WP_Query(
    array(
        'post_type' = 'page',
    )
  );
  if ( $template_query-have_posts() ) {
    while ( $template_query-have_posts() ) {
        $template_query-the_post();
         $post_content = get_the_content();
        if ( has_shortcode( $post_content, 'availability' ) ) {
            $template_id = get_the_ID();
            //var_dump($template_id);
        }
    }
    wp_reset_postdata();
  }
}
add_action( 'init', 'availabilty_id' );