Spring Data Mongo-如何通过分页执行分组？

Question

我正在使用Spring Boot v2.2.2.RELEASE和Spring Data MongoDB。在此示例中，我正在按部门代码分组执行，并让该组下的所有员工参加。

样本数据-

{
    "firstName" : "Laxmi",
    "lastName" : "Parate",
    "email" : "[email protected]",
    "createDate" : ISODate("2014-10-10T07:07:49.000Z"),
    .........
    .........
    "status" : "A",
    "departments" : {
        "deptCd" : "A",
        "deptName" : "Software Development",
        "status" : "A",
    }
}

如果我们可以使用Spring Data Repository Query做到这一点，那就太好了。

public interface EmployeeRepository extends CrudRepository<Employee, Object>{

    @Query(value = "{}", fields = "{'departments': 1}")
    Page<Employee> findAllGroupByDept(Pageable pageRequest);
}

Answer 1

至少我能够通过下面的查询获取数据，但是仍然难以以Pages的形式生成数据

db.country.aggregate([
  {
    $group: {
      _id: "$departments.deptCd",
      matches: { $push: '$$ROOT' }
    }
  }
])

参考：Keeping field in mongodb group by和how to group in mongoDB and return all fields in result