How to save a foreign key in hibernate?

Question

I have a timesheet entity that has a list of tasks. When I try to add a new task to the timesheet everything gets saved except the foreign key. Any ideas how should I avoid making a method with a custom SQL query and do the job in hibernate fashion?

My timesheet entity:

@Entity
@Table(name = "timesheet")
public class Timesheet {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    private LocalDate date;

    @OneToMany(
            mappedBy = "timesheet",
            cascade = CascadeType.ALL,
            orphanRemoval = true,
            fetch = FetchType.EAGER
    )
    @JsonManagedReference
    private List<Task> tasks = new ArrayList<>(); 

My task:

@Entity
@Table(name = "task")
public class Task {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    private String title;

    private Integer hours;

    @ManyToOne
    @JsonBackReference
    private Timesheet timesheet; 

Service impl:

 @Override
    public void addTask(int timesheetId, TaskVO taskVO) {
        Timesheet oldTimesheet = timesheetRepository.findById(timesheetId).orElse(new Timesheet(date, tasks));
        Task task = taskMapper.transformToEntity(taskVO);
        taskRepository.save(task);
        oldTimesheet.getTasks().add(task);
        timesheetRepository.save(oldTimesheet);
    }

Answer 1

There is a missing link from the Task object to its owner Timesheet . Filling this relationship should persist the foreign key column in the Task table, otherwise the JPA persister will still view the timesheet field as null in the Task object:

@Override
public void addTask(int timesheetId, TaskVO taskVO) {
    Timesheet oldTimesheet = timesheetRepository.findById(timesheetId).orElse(new Timesheet(date, tasks));
    Task task = taskMapper.transformToEntity(taskVO);
    task.setTimesheet(oldTimesheet);   // need this
    taskRepository.save(task);
    oldTimesheet.getTasks().add(task);
    timesheetRepository.save(oldTimesheet);
}

Note: I'm not sure about this, but you maybe don't need to save the task, if you are saving the timesheet at the end, since you have CascadeType.ALL on the tasks field.