def get_data(self):
        domains = []
        domain_id = api.keystone.get_effective_domain_id(self.request)

        if policy.check((("identity", "identity:list_domains"),),
                        self.request):
            try:
                if domain_id:
                    domain = api.keystone.domain_get(self.request, domain_id)
                    domains.append(domain)
                else:
                    domains = api.keystone.domain_list(self.request)
            except Exception:
                exceptions.handle(self.request,
                                  _('Unable to retrieve domain list.'))
        elif policy.check((("identity", "identity:get_domain"),),
                          self.request):
            try:
                domain = api.keystone.domain_get(self.request, domain_id)
                domains.append(domain)
            except Exception:
                exceptions.handle(self.request,
                                  _('Unable to retrieve domain information.'))
        else:
            msg = _("Insufficient privilege level to view domain information.")
            messages.info(self.request, msg)
        return domains