Spring JPA - deleting child element doesn't reflect in database table - spring

Question

I'm having problems deleting the child element of a one-to-many relationship entity.
Here's a code snippet:
#Override
#Transactional
public void deleteTask(UUID listId, UUID taskId) {
TaskList list = repo.findOne(listId);
System.out.println("Old List: " + list);
for(Task t : list.getTasks()) {
if(t.getId().toString().equals(taskId.toString())) {
System.out.println(list.getTasks().remove(t));
System.out.println("Task with id " + taskId + " deleted.");
}
}
System.out.println("New List: " + repo.save(list));
}
The Task class is this:
#Entity(name = "task")
public class Task implements Serializable {
// Id and 3 fields
#ManyToOne
#JoinColumn(name="tasklist_id")
private TaskList parentList;
// 3 more fields
// Constructor
public Task() {}
//Getters and Setters
}
and the TaskList class is this:
#Entity(name = "task_list")
public class TaskList implements Serializable {
// Id and two fields
#OneToMany(mappedBy="parentList", cascade={CascadeType.ALL})
private List<Task> tasks;
// Constructor
public TaskList() {}
}
The Task entity is the child, and even though the save() function returns the truncated TaskList, I can't get the changes to show in a separate query to the database. The number of tasks remains the same. However, deleting a list through repo.delete(listId) works fine with both the list and its tasks gone.
Here, repo is a repository corresponding to the parent TaskList class. All operations to the child Task class happen through a #OneToMany({cascade=CascadeType.ALL}) relation.
For some reason, searching for all TaskLists using repo.findAll() also returns faulty results.
I'm obviously doing something fundamentally wrong. Please tell me what to do.

Answer 1

You need to add orphanRemoval = true to your mapping:
#OneToMany(mappedBy="parentList", cascade={CascadeType.ALL}, orphanRemoval=true)
list.getTasks().remove(t) just removes entity from the collection, so you need to tell JPA to remove it also from DB. This is done by the orphanRemoval attribute.

Answer 2

Here's my task list
#Entity(name = "TASK_LIST")
public class TaskList {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column(name = "NAME")
private String name;
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
#JoinColumn(name = "task", referencedColumnName = "id", nullable = false)
private List<Task> tasks = new ArrayList<Task>();
Here's my repository
#Repository
public interface TaskListRepository extends JpaRepository<TaskList, Long> {
}
Here's my test
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations = "classpath:applicationContext-test.xml")
public class TaskListRepositoryTest {
#Autowired
private TaskListRepository repository;
#Autowired
private TaskService service;
#Test
public void test1() throws SQLException {
TaskList taskList = new TaskList();
taskList.getTasks().add(makeTask("name1", "description1"));
taskList.getTasks().add(makeTask("name2", "description2"));
taskList.getTasks().add(makeTask("name3", "description3"));
taskList.getTasks().add(makeTask("name4", "description4"));
taskList.getTasks().add(makeTask("name5", "description5"));
service.save(taskList);
TaskList findOne = repository.findOne(1l);
assertEquals(5, findOne.getTasks().size());
taskList.getTasks().remove(2);
service.save(taskList);
findOne = repository.findOne(1l);
assertEquals(4, findOne.getTasks().size());
}
#Test
public void test2() throws SQLException {
TaskList findOne = repository.findOne(1l);
assertEquals(4, findOne.getTasks().size());
}
private Task makeTask(String name, String description) {
Task task = new Task();
task.setName(name);
task.setDescription(description);
return task;
}