java IncorrectResultSizeDataAccessException - 试图简单地获取最近的行
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IncorrectResultSizeDataAccessException - Trying to simply get the most recent row
提问by Christopher
I have a Spring CrudRepository called 'ImportReceiptRepository'.
我有一个名为“ImportReceiptRepository”的 Spring CrudRepository。
I'm simply trying to compose a method which grabs the first row in an order by clause.
我只是想编写一个方法，该方法可以在 order by 子句中获取第一行。
Here's what I'm using currently:
这是我目前使用的：
ImportReceipt importReceipt = this.importReceiptRepository.getOneByImportTypeOrderByTimestampDesc(importType);
The issue is that when there is more than a single row returned, Spring throws a:
问题是当返回多于一行时，Spring 会抛出：
org.springframework.dao.IncorrectResultSizeDataAccessException: result returns more than one elements; nested exception is javax.persistence.NonUniqueResultException: result returns more than one elements
How should I rename this CrudRepository function to simply grab the first row when there are 0-n rows returned?
当返回 0-n 行时，我应该如何重命名这个 CrudRepository 函数以简单地获取第一行？
回答by Christopher
Simply using Pageable was the key:
简单地使用 Pageable 是关键：
List<ImportReceipt> findByImportType(String importType, Pageable pageable);
and calling it like:
并称之为：
List<ImportReceipt> importReceipts = this.importReceiptRepository.findByImportType(importType, new PageRequest(0, 1, Direction.DESC, "Timestamp"));
ImportReceipt importReceipt = importReceipts.get(0);
Credit: How to combine pagination with a criteria query in Spring Data JPA?
回答by Oliver Drotbohm
As of the upcoming version 1.7 of Spring Data JPA, the query method as you originally declared it works out of the box. See this ticketfor details. The support has already been published in the first milestone of the release.
从即将发布的 Spring Data JPA 1.7 版开始，您最初声明的查询方法开箱即用。详情请参阅这张票。该支持已在该版本的第一个里程碑中发布。
回答by liranfar89
You can make it even simpler by findFirst:
你可以通过 findFirst 让它变得更简单：
ImportReceipt findFirstByImportType(String importType);
For more info: Limiting Query Results
更多信息：限制查询结果
