Invalidate cached data for this page.

def invalidate(self):
        """Invalidate cached data for this page."""

        cache.delete(self.PAGE_LANGUAGES_KEY % (self.id))
        cache.delete('PAGE_FIRST_ROOT_ID')
        self._languages = None
        self._complete_slug = None
        self._content_dict = dict()

        p_names = [p.name for p in get_placeholders(self.get_template())]
        if 'slug' not in p_names:
            p_names.append('slug')
        if 'title' not in p_names:
            p_names.append('title')
        # delete content cache, frozen or not
        for name in p_names:
            # frozen
            cache.delete(PAGE_CONTENT_DICT_KEY % (self.id, name, 1))
            # not frozen
            cache.delete(PAGE_CONTENT_DICT_KEY % (self.id, name, 0))

        cache.delete(self.PAGE_URL_KEY % (self.id))