public function get_participants(string $id_chat): ?array
  {
    if ( $this->check() ){
      return $this->db->get_field_values('bbn_chats_users', 'id_user', ['id_chat' => $id_chat]);
    }
    return null;
  }
public function get_participants(string $id_chat): ?array
  {
    if ( $this->check() ){
      return $this->db->get_field_values('bbn_chats_users', 'id_user', ['id_chat' => $id_chat]);
    }
    return null;
  }
public function get_participants ( string $ id_chat ) : ? array { if ( $ this -> check ( ) ) { return $ this -> db -> get_field_values ( 'bbn_chats_users' , 'id_user' , [ 'id_chat' => $ id_chat ] ) ; } return null ; }
Returns the participants of the given chat as an array of id_user.

@param string $id_chat
@return array|null
Returns the participants of the given chat as an array of id_user .