LazyInitializationException: could not initialize proxy - no Session

Question

I use spring-data-jpa with spring-boot(v2.0.0.RELEASE), I just wrote a CRUD demo on MySQL, but an exception occurs during runtime, source code as f

Answer 1

In the service class please add a setter for entity manager by using the annoattion @PersistenceContext. To be specific, use

 @PersistenceContext(type = PersistenceContextType.EXTENDED)

In this way, you can access lazy property.

Answer 2

Your test should be like this:

@RunWith(SpringRunner.class)    


@SpringBootTest
@Transactional    

public class QuestionTesting {   

    @Test    
    public void test() {    

    }    
}    

Answer 3

You can add @Transactional annotation to your test method to avoid this exception.

Method getOne return the 'reference' (proxy) of the entity which properties can be lazy loaded. See it code - it uses getReference method of EntityManager. From it javadoc:

Get an instance, whose state may be lazily fetched.

In Spring the implementation of EntityManager is org.hibernate.internal.SessionImpl - so without the Session the Spring can not get this method.

To have a session you can just create a transaction...