def get_page_ids_by_slug(self, slug):
        """Return all page's id matching the given slug.
        This function also returns pages that have an old slug
        that match.

        :param slug: the wanted slug.
        """
        ids = self.filter(type='slug', body=slug).values('page_id').annotate(
            max_creation_date=Max('creation_date')
        )
        return [content['page_id'] for content in ids]
Return all page's id matching the given slug.
        This function also returns pages that have an old slug
        that match.

        :param slug: the wanted slug.