public removeById(id: any): Promise<T> {
     return this._model.findByIdAndRemove(id).exec();
 }

 public remove(query: any): Promise<T> {
     return this._model.remove(query).exec();
 }

 public findById(id: any): Promise<T> {
     return this._model.findById(id).exec();
 }

 public async size(): Promise<number> {
     return this._model.count({}).exec();
 }

 public findPaginated(query: Query<T>, pagination: PaginateOptions): Promise<PaginateResult<T>> {
     return this._model.paginate(query, pagination);
 }

 public findOne(query: any): Promise<T> {
     return this._model.findOne(query).exec();
 }

 public getFields(query: any, fields: any): Promise<any> {
     return this._model.find(query).select(fields).exec();
 }

 public getFieldsById(id: any, fields: any): Promise<any> {
     return this._model.findById(id).select(fields).exec();
 }

 public async contains(query: any): Promise<boolean> {
     return (await this._model.paginate(query, {limit: 0})).total > 0;
 }