如何在Spring Boot Data Jpa应用程序中使用Criteria查询

问题描述

我有一个使用 Spring Boot Data jpa 的应用程序。
到目前为止，我正在使用这样的存储库

I have an application that uses Spring Boot Data jpa .So far i am using a repository like this

public interface StudentRepository extends CrudRepository<StudentEntity, Integer>{
    @Query(value = ""
        + "SELECT s.studentname "
        + "FROM   studententity s, "
        + "       courseentity c "
        + "WHERE  s.courseid = c.courseid "
        + "       AND s.courseid IN (SELECT c.courseid "
        + "                          FROM   courseentity c "
        + "                          WHERE  c.coursename = ?1)")
    List<String> nameByCourse(String coursename);
}

如何使用 Criteria Query Hibernate在Spring Boot应用程序中提供这种情况

How can i make use of Criteria Query That Hibernate Provides for such cases in a Spring Boot Application

推荐答案

从

From the docs

定义一个类似于这样的接口

Define an interface like so

public interface StudentRepositoryCustom {

    List<String> nameByCourse(String coursename);

}

然后像这样定义这个接口的自定义实现 p>

Then define a custom implementation of this interface like so

@Service
class StudentRepositoryImpl implements StudentRepositoryCustom {

    @PersistenceContext
    private EntityManager em;

    public List<String> nameByCourse(String coursename) {
        CriteriaBuilder cb = em.getCriteriaBuilder();
        //Using criteria builder you can build your criteria queries.
    }

}

现在您可以扩展此自定义存储库

Now you can extend this custom repository implementaion in your JPA repository like so.

public interface StudentRepository extends CrudRepository<StudentEntity, Integer>, StudentRepositoryCustom {

}

详细了解条件查询和条件生成器

Learn more about criteria query and criteria builder here

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