Unexpected NullPointerException in Spring Boot Application with JPA and Optional Handling
I'm attempting to set up I'm collaborating on a project where I'm trying to configure I'm sure I'm missing something obvious here, but I'm working with a `NullPointerException` when trying to retrieve an entity using JPA with Spring Boot, specifically when I am handling an `Optional` response. The scenario arises in the following method where I attempt to find a user by their ID: ```java public Optional<User> findUserById(Long id) { return userRepository.findById(id); } ``` The `userRepository` is correctly set up to extend `JpaRepository<User, Long>`, and it looks like this: ```java @Repository public interface UserRepository extends JpaRepository<User, Long> { } ``` However, when I call this method in my service layer and try to fetch the user, I get a `NullPointerException` at the line where I'm trying to access the user's properties like this: ```java public UserDTO getUserDTO(Long id) { User user = findUserById(id).orElseThrow(() -> new NoSuchElementException("No user found")); return new UserDTO(user.getName(), user.getEmail()); } ``` The exception stack trace shows that the `user` object is `null`, leading to the behavior: ``` java.lang.NullPointerException: want to invoke "User.getName()" because "user" is null ``` I've verified that the ID passed exists in the database, and I've also looked into the transaction boundaries, which seem to be set correctly. Additionally, I'm using Spring Boot 2.5.4 and Hibernate 5.5.3. I tried to log the ID before fetching the user, and it prints the expected value. I'm unsure why `userRepository.findById(id)` is returning an empty `Optional`, even though the record is present in the database. Is there something I might be missing regarding the configuration, or could there be a caching scenario with Hibernate? Any help would be appreciated! For context: I'm using Java on macOS. I'd really appreciate any guidance on this. Is there a better approach? The stack includes Java and several other technologies. Is there a simpler solution I'm overlooking? My development environment is CentOS.