Spring存储库中的MongoDB查询:过滤后的记录数限制 [英] MongoDB query in Spring repository: limit number of records after filter

问题描述

我有以下查询(为简单起见，使用了硬编码的参数)，使用Spring存储库中的"@Query"注释:

I have the following query (with hard-coded parameters for simplicity) , using the "@Query" annotation within a Spring repository:

@Query("{$ query:{status:'Failed'}，$ maxScan:10}")

@Query("{$query : {status:'Failed'}, $maxScan: 10}")

此查询的目的是从数据库中读取状态为失败"的前10条记录(这些记录是系统作业).但是，查询将首先读取10条记录，然后从那10条记录中读取状态为失败"的记录.

The intent of this query is to read the first 10 records from the database that have a status of "Failed" (the records are system jobs). However, the query will first read 10 records, then read records with a status of "Failed" from those 10 records.

我需要在应用过滤器之后而不是之前将限制应用于结果集.如何修改上述查询，以返回应用过滤器逻辑后读取的结果集的前10条记录，即状态为失败"的前10条记录?

I need to apply the limit to a resultset after the filter is applied, not before. How can I modify the above query to return the first 10 records of the resultset that is read after the filter logic is applied, i.e. the first 10 records with a status of "Failed"?

谢谢.

推荐答案

在使用Spring Data MongoDB时，我认为通常您会希望使用Pageable接口进行这些查询.示例:

When using Spring Data MongoDB, I think generally you'll want to use the Pageable interface for these queries. Example:

@Query("{status: 'Failed'}")
List<Record> findFailedRecords(Pageable pageable);

// or even better without the @Query annotation just:

List<Record> findByStatus(String status, Pageable pageable);

然后致电:

yourRecordRepo.findFailedRecords(new PageRequest(0, 10));

// or using the other method:

yourRecordRepo.findByStatus("Failed", new PageRequest(0, 10));

这将获取10条失败记录的首页.

That will fetch the first page of 10 failed Records.

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