if (this._getModel()._name < joins[key].model._getModel()._name) {
                linksPks.push(this[joins[key].leftKey] + '_' + this[key][i][joins[key].rightKey]);
              } else {
                linksPks.push(this[key][i][joins[key].rightKey] + '_' + this[joins[key].leftKey]);
              }