sql - 我需要使用 join fetch，但它会导致 "query specified join fetching, but the owner of the fetched association was not present in the select list"

Question

我有以下查询:

@Query("SELECT new de.projectemployee.ProjectEmployee(employee) " +
       "FROM ProjectEmployee projectEmployee JOIN FETCH projectEmployee.employee employee " +
       "WHERE projectEmployee.project.id = :id")
List<ProjectEmployee> findInOneRequestByProjectId(@Param("id") long id);

我收到以下错误:

org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list

正如许多解决方案所建议的那样，我可以将 JOIN FETCH 替换为 JOIN。但是这个解决方案的问题是它会导致 n+1 个请求。有没有其他方法可以修复错误？

Answer 1

Fetch 用于填充对象中的延迟加载字段，这里没有用。只需从您的查询中删除 FETCH 即可。