今天我們介紹的是jpa刪除和事務(wù)的一些坑，接下來看看具體內(nèi)容。

業(yè)務(wù)場(chǎng)景(這是一個(gè)在線考試系統(tǒng))和代碼：根據(jù)問題的id刪除答案

repository層:

int deleteByQuestionId(Integer questionId);

service 層:

public void deleteChoiceAnswerByQuestionId(Integer questionId) {
choiceAnswerRepository.deleteByQuestionId(questionId);

測(cè)試層:

@Test
public void testDeleteByQuestionId() {
 choiceAnswerService.deleteChoiceAnswerByQuestionId(5);
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
}

問題1：如果各層都不加事務(wù)管理的話
@Transactional

會(huì)報(bào)這個(gè)錯(cuò)誤

org.springframework.dao.InvalidDataAccessApiUsageException: No EntityManager with actual transaction available for current thread - cannot reliably process ‘remove' call; nested exception is javax.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread - cannot reliably process ‘remove' call

當(dāng)我們除了query外的modiy和delete外如果沒有各層的方法中進(jìn)行事務(wù)管理的話也就是沒加@Transactional話會(huì)報(bào)錯(cuò)

問題2：只在test層加@Transactional
沒有錯(cuò)誤但是數(shù)據(jù)并沒有被刪除,在用IDEA的調(diào)試是，在執(zhí)行這個(gè)測(cè)試方法的過程時(shí)還可以在choiceanswer表中進(jìn)行操作并沒有加鎖事務(wù)并沒有起作用

問題3:只在 Repository層加@Transactional

public void deleteChoiceAnswerByQuestionId(Integer questionId) {
choiceAnswerRepository.deleteByQuestionId(questionId);
System.out.println(“hehehhe”);
System.out.println("hehehhe");
// questionRepository.delete(5);
System.out.println(“hehehhe”);
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
 System.out.println("hehehhe");
}

這時(shí)當(dāng)執(zhí)行完

choiceAnswerRepository.deleteByQuestionId(questionId);

數(shù)據(jù)里面被修改

問題4:只在 service層加@Transactional

當(dāng)只有執(zhí)行完service內(nèi)的對(duì)應(yīng)方法時(shí)數(shù)據(jù)才會(huì)被刪除

問題5:在service 層和Repository都加上@transactional

當(dāng)只有執(zhí)行完service內(nèi)的對(duì)應(yīng)方法時(shí)數(shù)據(jù)才會(huì)被刪除

問題6:只要在test(或者是除了service層和Repository層）加上@Transactional,不管service層和Repository層加不加@Transactional數(shù)據(jù)都不會(huì)被刪除

問題7:

@Modifying
@Query(“delete from ChoiceAnswer c where c.question.id=?1 “)
@Transactional
int deleteByQuestionId(Integer questionId);

與

@Transactional
int deleteByQuestionId(Integer questionId);

有什么區(qū)別,上面的會(huì)直接執(zhí)行delete語句

下面的會(huì)先執(zhí)行select 再執(zhí)行delete

總結(jié):

事務(wù)管理只有在service加上事務(wù)管理才起作用,query不需要事務(wù)管理但是delete update但需要事務(wù)管理為了不在Service層不加事務(wù)管理可以再Repository層的delete uodate加上@transactional 但這樣不能真正保持事務(wù)的完整性.

本文關(guān)于Spring boot jpa 刪除數(shù)據(jù)和事務(wù)管理的問題實(shí)例詳解的介紹就到這里，希望對(duì)大家有所幫助，歡迎大家參閱本站其他專題。