DataManager accepting a Promise

public processQuery(dataManager: DataManager, query: Query): Object {
  const def = new Deferred();

  this.service.getList(this.collectionFilterParamsInput)
    .then((result) => {
      def.resolve({ result: result.slice(0, 50), count: 50 });
    }).catch((error) => {
    def.reject({ result: [], count: 0 });
  });

  return def.promise;
}

if (!this.dataSource.offline && (this.dataSource.url !== undefined && this.dataSource.url !== '')
    || (!isNullOrUndefined(this.adaptor[makeRequest]))) {
    var result = this.adaptor.processQuery(this, query);
    if (!isNullOrUndefined(this.adaptor[makeRequest])) {
        this.adaptor[makeRequest](result, deffered, args, query);
    }
    else if (!isNullOrUndefined(result.url)) {
        this.makeRequest(result, deffered, args, query);
    }
    else {
        args = DataManager.getDeferedArgs(query, result, args);
        deffered.resolve(args);
    }
}
else {
    DataManager.nextTick(function () {
        var res = _this.executeLocal(query);
        args = DataManager.getDeferedArgs(query, res, args);
        deffered.resolve(args);
    });
}
if (done || fail) {
    deffered.promise.then(done, fail);
}
if (always) {
    deffered.promise.then(always, always);
}
return deffered.promise;