code: function(query) {
          var q = rql2es(_.rql(query)),
              mapFn = q.fields ?
                            function(x) { return x.fields; } 
                          : function(x) { return x._source; };
          return ajax('POST', this._url + '/_search', q)
              .then(function(result) {
                  return result.hits.hits.map(mapFn);
              });
      }
docs: Execute RQL query