英文:
@Transactional(propagation = Propagation.SUPPORTS) no transaction is in progress
问题
我有一个简单的CRUD项目。
我有一个使用Hibernate 5和Spring Boot的简单CRUD项目。当我使用`@Transactional(propagation = Propagation.SUPPORTS)`时，我捕获到错误`javax.persistence.transactionrequiredexception: no transaction is in progress`。当我使用`@Transactional(propagation = Propagation.REQUIRED)`时，一切正常。
我做错了什么？
Repository:
@Transactional(propagation = Propagation.SUPPORTS)
public Toy getToy(String companyName, String toyName) throws Exception {
Session session = sessionFactory.getCurrentSession();
try {
Query query = session.createQuery("from Toy where company.name = :company and name = :name");
query.setParameter("company", companyName);
query.setParameter("name", toyName);
return (Toy) query.getSingleResult();
} catch (NoResultException e) {
Toy toy = new Toy();
Query query = session.createQuery("from Company where name = :name");
query.setParameter("name", companyName);
Company company = (Company) query.getSingleResult();
toy.setCompany(company);
toy.setName(templateName);
toy.bought(0);
toy.setViewed(0);
return toy;
}
}
英文:
I have a simple CRUD project.
I have a simple CRUD project with Hibernate 5 and Spring Boot. When I use @Transactional(propagation = Propagation.SUPPORTS), I catch the error javax.persistence.transactionrequiredexception: no transaction is in progress. When I use the @Transactional(propagation = Propagation.REQUIRED), everything is fine.
What I doing wrong?
Repository:
@Transactional(propagation = Propagation.SUPPORTS)
public Toy getToy(String companyName, String toyName) throws Exception {
Session session = sessionFactory.getCurrentSession();
try {
Query query = session.createQuery("from Toy where company.name = :company and name = :name");
query.setParameter("company", companyName);
query.setParameter("name", toyName);
return (Toy) query.getSingleResult();
} catch (NoResultException e) {
Toy toy = new Toy();
Query query = session.createQuery("from Company where name = :name");
query.setParameter("name", companyName);
Company company = (Company) query.getSingleResult();
toy.setCompany(company);
toy.setName(templateName);
toy.bought(0);
toy.setViewed(0);
return toy;
}
}
答案1
得分: 0
REQUIRED是默认的传播行为。Spring会检查是否存在活动事务，如果没有任何事务存在，则会创建一个新事务。否则，业务逻辑会追加到当前活动事务中。
SUPPORTS，Spring首先检查是否存在活动事务。如果存在事务，则将继续使用现有事务。如果没有事务，则会以非事务方式执行。
因此，你之所以在进入“SUPPORT传播”事务包裹的方法时出现错误，仅仅是因为没有事务存在。
顺便说一下，SUPPORTS的使用情况非常有限...大多数情况下，使用默认的“REQUIRED”正好满足我们的需求。
英文:
REQUIRED is the default propagation. Spring checks if there is an active transaction, then it creates a new one if nothing existed. Otherwise, the business logic appends to the currently active transaction.
SUPPORTS, Spring first checks if an active transaction exists. If a transaction exists, then the existing transaction will be used. If there isn't a transaction, it is executed non-transactional.
So you got this error simply because no transaction exists when entering inside the method wrap by "SUPPORT-propagation" transaction.
By the way SUPPORTS have very limited use-cases... most of the time using default "REQUIRED" offers exactly what we need.
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