An intermediary proxy server serves as your connection to the internet. End consumers are separated from the websites they visit by an intermediary server. Relying on your demands, use case, or corporate policy, proxy servers offer varied degrees of functionality, privacy and security. “Org.hibernate.lazyinitializationexception: could not initialize proxy – no session” is one of the most common error that shows up in many ways. This article will give you some solutions to fix it. Read on.

When do you encounter the error “org.hibernate.lazyinitializationexception: could not initialize proxy – no session”?

When you are trying to call getRoles method out of the session as the following:

@Test
public void whenAccessUserRolesOutsideSession_thenThrownException() {
    User detachedUser = createUserWithRoles();
    Session session = sessionFactory.openSession();
    session.beginTransaction();
    User persistentUser = session.find(User.class, detachedUser.getId());
    session.getTransaction().commit();
    session.close();
    thrown.expect(LazyInitializationException.class);
    System.out.println(persistentUser.getRoles().size());
}

You can easily get the error:

Org.hibernate.lazyinitializationexception: could not initialize proxy - no session

How to fix the error “org.hibernate.lazyinitializationexception: could not initialize proxy – no session”

Option 1: In upper layer let’s open session

In upper layer let’s open session to fix the error “org.hibernate.lazyinitializationexception: could not initialize proxy – no session”.

It is ideal to start a session on the persistence layer, perhaps using the DAO Pattern. To safely access the linked objects, you can start the session in the upper layers. You might choose to open the session in the View layer, for example. You’ll observe a longer response time as a result, which will have an impact on how well the program performs. When it comes to the Separation of Concerns principle, this solution is the opposite of a pattern. Long-running transactions and data integrity breaches might also result from it.

Option 2: Try adding @Transactional

To the validate method, try adding @Transactional:

@Override
@Transactional(readOnly=true)
public void validate(Object target, Errors errors) {
    ...
}

The result is that each query will run in its own session that is instantly closed since there is not @Transactional annotation, preventing a session from being associated with the method. Unlike session.get(), the function session.load() always returns a proxy. The proxy is therefore returned, but the session that created the proxy is immediately closed as a result of the missing @Transactional. The first time the proxy is accessed, its session is closed, resulting in the “no session” error.

Option 3: Utilize FetchType.EAGER Strategy

Utilizing FetchType.EAGER Strategy is a great way for you to solve the error.

”org.hibernate.lazyinitializationexception: could not initialize proxy – no session“.

This tactic can be combined with the @OneToMany annotation as following:

@OneToMany(fetch = FetchType.EAGER)
@JoinColumn(name = "user_id")
private Set<Role> roles;

When you need to fetch the related collection for the majority of your use cases, this is sort of a compromised option.

For the majority of business flows, declaring the EAGER retrieve type is more simpler than explicitly fetching the collection.

Option 4: Utilize Join Fetching

Additionally, a JOIN Acquire command in JPQL can be used to instantly fetch the related collection:

SELECT u FROM User u JOIN FETCH u.roles

Or you can utilize the Hibernate Criteria API:

Criteria criteria = session.createCriteria(User.class);
criteria.setFetchMode("roles", FetchMode.EAGER);

Here, you specify that the associated collection and the User object should both be retrieved from the database in one round trip. Since there is no longer a requirement to retrieve the related objects one at a time, using this query increases iteration efficiency.

This is the most effective and precise method to fix the error ”org.hibernate.lazyinitializationexception: could not initialize proxy – no session“.

Conclusion

Above are the best solutions for the ”org.hibernate.lazyinitializationexception: could not initialize proxy – no session“ problem. We hope you will enjoy our article about the error. With this knowledge, we know that you can fix your error quickly by following these steps! If you still have any other questions about fixing this syntax error, please leave a comment below. Thank you for reading!

Read more

→ Solutions For The Error: “pytube.exceptions.RegexMatchError: init: could not find match for ^w+W” in Python?