springboot jpa---->总结一下遇到的问题

Native Query throw exception

• dto code

import lombok.Value;

@Value
public class IdsOnly {

    Integer id;
    String otherId;
}

• repository

public interface TestTableRepository extends JpaRepository<TestTable, Integer> {

    @Query(value = "select id, otherId from TestTable where CreationDate > ?1", nativeQuery = true)
    public Collection<IdsOnly> findEntriesAfterDate(Date creationDate);
}

• service

List<IdsOnly> results = ttRepo.findEntriesAfterDate(theDate);  

• exception

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap] to type [com.example.IdsOnly]

解决方法有两种

• 使用NativeQuery：将IdsOnly更换成接口，提供属性的get方法。

public interface IdsOnly {
    Integer getId();
    String getOtherId();
}

• 不使用NativeQuery

@Query("select new com.example.IdsOnly(t.id, t.otherId) from TestTable t where t.creationDate > ?1")

Jpa中没有update方法

jpa中只有save方法，如果你传递的对象的主键在数据库中存在，那么就是更新操作。否则就是插入操作。

Delete operation

JpaRepository Not supported for DML operations [delete query]

• Repository: add @Modifying

@Modifying
void deleteByUserIdAndToolId(Integer userId, Integer toolId);

• Service: add @Transactional

@Transactional
public void doDeleteUserTool(Integer userId, Integer toolId) {
    userToolMapper.deleteByUserIdAndToolId(userId, toolId);
}

To be continue

Industry is the soul of business and the keystone of prosperity.