How to handle unidirectional many-to-many relations with Ebean - many-to-many

Question

I have a problem with Ebean. I have the usual Objects PsecUser, PsecRoles and PsecPermission.
A user can have many Permissions or Roles and a Role can have many Permission.
Here the code (extract):
#Entity
public class PsecPermission {
#Id
#GeneratedValue
private Long id;
#Column(unique=true, nullable=false)
private String name;
#Column(nullable=false)
private String type = PsecBasicPermission.class.getName();
#Column(nullable=false)
private String target;
#Column(nullable=false)
private String actions;
}
#Entity
public class PsecRole {
#Id
#GeneratedValue
private Long id;
#Column(unique=true, nullable=false)
private String name;
#Temporal(TemporalType.TIMESTAMP)
private Date lastUpdate;
#ManyToMany(fetch=FetchType.EAGER)
private List<PsecPermission> psecPermissions;
private boolean defaultRole = false;
}
I wrote the following helper-method:
public PsecRole createOrUpdateRole(String name, boolean defaultRole, String... permissions) {
PsecRole result = server.find(PsecRole.class).
where().eq("name", name).findUnique();
if (result == null) {
result = new PsecRole();
result.setName(name);
}
final List<PsecPermission> permissionObjects = server.find(PsecPermission.class).
where().in("name", (Object[])permissions).findList();
result.setPsecPermissions(permissionObjects);
result.setDefaultRole(defaultRole);
final Set <ConstraintViolation <PsecRole>> errors =
Validation.getValidator().validate(result);
if (errors.isEmpty()) {
server.save(result);
server.saveManyToManyAssociations(result, "psecPermissions");
} else {
log.error("Can't save role: " + name +"!");
for (ConstraintViolation <PsecRole> constraintViolation : errors) {
log.error(" " + constraintViolation);
}
}
return result;
}
and try the following test:
#Test
public void testCreateOrUpdateRole() {
String[] permNames = {"Test1", "Test2", "Test3"};
List <PsecPermission> permissions = new ArrayList <PsecPermission>();
for (int i = 0; i < permNames.length; i++) {
helper.createOrUpdatePermission(permNames[i], "target"+ i, "actions" +i);
PsecPermission perm = server.find(PsecPermission.class).where().eq("name", permNames[i]).findUnique();
assertThat(perm.getTarget()).isEqualTo("target" + i);
assertThat(perm.getActions()).isEqualTo("actions" + i);
permissions.add(perm);
}
PsecRole orgRole = helper.createOrUpdateRole(ROLE, false, permNames);
testRole(permNames, orgRole);
PsecRole role = server.find(PsecRole.class).where().eq("name", ROLE).findUnique();
testRole(permNames, role);
}
private void testRole(String[] permNames, PsecRole role) {
assertThat(role).isNotNull();
assertThat(role.getName()).isEqualTo(ROLE);
assertThat(role.isDefaultRole()).isEqualTo(false);
assertThat(role.getPermissions()).hasSize(permNames.length);
}
Which fails if it checks the number of permissions at the readed role. It's always 0.
I looked into the database and found that psec_role_psec_permission is alway empty.
Any idea what's wrong with the code?
You can get a pure Ebean-example from https://github.com/opensource21/ebean-samples/downloads it uses the eclipse-plugin from ebean.

Answer 1

There are two solutions for this problem:
Simply add cascade option at PsceRole
#ManyToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
private List<PsecPermission> psecPermissions;
and remove server.saveManyToManyAssociations(result, "psecPermissions"); you find it in the cascade-solution-branch.
The cleaner solution, because you don't need to define cascase- perhaps you don't want it:
Just don't replace the list, just add your entries to the list. Better is to add new and remove old one. This mean in createOrUpdateRole:
result.getPsecPermissions().addAll(permissionObjects);
instead of
result.setPsecPermissions(permissionObjects);