How to fix Hibernate LazyInitializationException: failed to lazily initialize a collection of roles, could not initialize proxy - no Session

How to fix Hibernate LazyInitializationException: failed to lazily initialize a collection of roles, could not initialize proxy - no Session.

👋 Hey there! Are you facing the dreaded LazyInitializationException in your Spring project? Don't worry, I've got you covered! In this blog post, I'll explain the common issues behind this exception, provide easy solutions, and offer a compelling call-to-action to keep you engaged. Let's dive in! 🏊‍♀️

Understanding the problem

So you encountered an org.hibernate.LazyInitializationException with the message "failed to lazily initialize a collection of roles, could not initialize proxy - no Session". This exception usually occurs when you try to access a lazily fetched collection outside the scope of an active Hibernate session.

In your case, the error is happening in the CustomAuthenticationProvider class when trying to read the list of authorities for the logged-in user. Here's the relevant code snippet:

List<AutorizacoesUsuario> list = user.getAutorizacoes();

Root cause analysis

To understand what's happening here, let's take a closer look at your entity classes. The Usuario class has a @ManyToMany relationship with the AutorizacoesUsuario class. By default, Hibernate uses lazy loading for collections, which means that the autorizacoes collection is not loaded immediately when you fetch a Usuario object from the database. Instead, it's loaded on-demand when you access the collection for the first time.

However, in your CustomAuthenticationProvider class, you're accessing the autorizacoes collection outside the scope of an active Hibernate session. This leads to the LazyInitializationException because Hibernate cannot initialize the proxy object associated with the collection.

Easy solutions

To fix this issue, you have a few options:

Option 1: Eagerly fetching the collection

One way to solve the problem is to change the fetching strategy for the autorizacoes collection to eager loading. This means that the collection will be loaded immediately when you fetch a Usuario object from the database.

To do this, you can modify the getAutorizacoes() method in the Usuario class and add the FetchType.EAGER option to the @ManyToMany annotation:

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinTable(name = "autorizacoes_usuario", joinColumns = { @JoinColumn(name = "fk_usuario") }, inverseJoinColumns = { @JoinColumn(name = "fk_autorizacoes") })
@LazyCollection(LazyCollectionOption.TRUE)
public List<AutorizacoesUsuario> getAutorizacoes() {
    return this.autorizacoes;
}

By eagerly fetching the autorizacoes collection, you ensure that it is loaded before you access it in the CustomAuthenticationProvider class. However, keep in mind that eager loading can lead to performance issues if the collection has a large number of elements.

Option 2: Initializing the collection manually

Another solution is to initialize the autorizacoes collection manually before accessing it in the CustomAuthenticationProvider class. This can be done by calling the Hibernate.initialize() method:

import org.hibernate.Hibernate;

// ...

List<AutorizacoesUsuario> list = user.getAutorizacoes();
Hibernate.initialize(list);

By explicitly initializing the collection, you ensure that it is loaded within the scope of an active Hibernate session. This avoids the LazyInitializationException.

Option 3: Using a custom query

If neither of the previous options works for you, you can consider writing a custom query to fetch the necessary data directly in the CustomAuthenticationProvider class. This way, you have full control over what data is fetched and how it is loaded.

📣 Your turn to engage!

I hope this blog post helped you understand and solve the LazyInitializationException issue in your Spring project! If you found this guide helpful, let me know in the comments section below. Also, don't hesitate to share your own experiences and challenges with Hibernate or Spring.

And remember, if you have any other tech-related questions or topics you'd like me to cover, feel free to reach out. I'm here to help you navigate the exciting world of technology! 🌟🚀

Happy coding! 😄