Spring JPA Transaction ID - spring-boot

Question

I have added an attribute to all my entities - transaction id - which is a sequence generated value that I bump up once in each transaction.
I also store the transaction id with user and start/end times so I have an audit trail for every change in the database.
What is the best way to handle storing a complete graph, where I basically only want to apply the transaction id to those entities that are actually dirty?
I can put a #PrePersist and #PreUpdate on the transaction id column, but how do I retrieve the value for the current transaction id? Is there a way to store and retrieve a value on the transaction object or other JPA controller? Do I need to use a ThreadLocal solution?

Answer 1

Ok, here is what I did. It seems to work in all of the use cases, though I have not done any performance testing, etc. If anyone sees anything that may be non-optimal or may fail in certain situations, please point it out.
Here is the base service class that all #Service implementations must extend:
public class BaseService
{
private final ActivityService activityService;
private final ApplicationEventPublisher applicationEventPublisher;
public static ThreadLocal<Activity> transaction = new ThreadLocal<>();
public BaseService(ActivityService activityService, ApplicationEventPublisher applicationEventPublisher)
{
this.activityService = activityService;
this.applicationEventPublisher = applicationEventPublisher;
}
Object executeWithinActivity(Updater updater)
{
boolean startedLocally = false;
try
{
if (transaction.get() == null)
{
startedLocally = true;
Activity activity = activityService.startTransaction();
transaction.set(activity);
}
return updater.execute(transaction.get());
}
finally
{
if (startedLocally)
{
applicationEventPublisher.publishEvent(new TransactionEvent());
Activity activity = transaction.get();
activityService.endTransaction(activity);
}
}
}
protected interface Updater
{
Object execute (Activity activity);
}
static class TransactionEvent
{
}
}
Activity is the entity that represents the stored transaction id:
#Entity
#Getter #Setter
#Table(name = "transactions", schema = "public", catalog = "euamdb")
public class Activity
{
#Id
#Column(name = "transaction_id", nullable = false)
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "tx_generator")
#SequenceGenerator(name = "tx_generator", sequenceName = "transaction_seq", allocationSize = 1)
private long transactionId;
#Basic
#Column(name = "user_id", length = 24)
private String userId;
#Basic
#Column(name = "transaction_start")
#CreationTimestamp
private Date transactionStart;
#Basic
#Column(name = "transaction_end")
#UpdateTimestamp
private Date transactionEnd;
#Override
public boolean equals(Object o)
{
if (this == o) return true;
if (!(o instanceof Activity)) return false;
Activity that = (Activity) o;
return transactionId == that.transactionId;
}
#Override
public int hashCode()
{
return Long.hashCode(transactionId);
}
}
ActivityService (which does not extend BaseService):
#Service
public class ActivityService
{
private final ActivityRepository activityRepository;
private final AuthUserService authService;
#Autowired
public ActivityService(ActivityRepository activityRepository, AuthUserService authService)
{
this.activityRepository = activityRepository;
this.authService = authService;
}
#Transactional
public Activity startTransaction()
{
Activity activity = new Activity();
activity.setTransactionStart(new Date());
activity.setUserId(authService.getAuthenticatedUserId());
activityRepository.save(activity);
return activity;
}
#Transactional
public void endTransaction(Activity activity)
{
activity.setTransactionEnd(new Date());
activityRepository.save(activity);
}
}
The base entity class for all entities (excepting Activity):
#MappedSuperclass
#Getter #Setter
public class BaseEntity
{
#Basic
#Column(name = "transaction_id")
private Long transactionId;
#PrePersist
#PreUpdate
public void setupTransaction ()
{
ThreadLocal<Activity> transaction = BaseService.transaction;
Activity activity = transaction.get();
long transactionId = activity.getTransactionId();
setTransactionId(transactionId);
}
}
An example of a service:
#Service
public class OrganizationService extends BaseService
{
private final OrgUserRepository orgUserRepository;
private final UserService userService;
#Autowired
public OrganizationService(ActivityService activityService,
OrgUserRepository orgUserRepository,
UserService userService,
ApplicationEventPublisher applicationEventPublisher)
{
super(activityService, applicationEventPublisher);
this.orgUserRepository = orgUserRepository;
this.userService = userService;
}
#Transactional
public OrgUser save(User user, OrgUser orgUser)
{
return (OrgUser) executeWithinActivity(activity ->
{
orgUser.setUser(userService.save(user));
return orgUserRepository.save(orgUser);
});
}
}
UserService also will extend BaseService and the save(OrgUser) method will also executeWithinActivity.
Finally, the commit listener:
#Component
public class AfterCommitListener
{
#TransactionalEventListener(phase = TransactionPhase.AFTER_COMPLETION)
public void doAfterTxComplete(BaseService.TransactionEvent event)
{
BaseService.transaction.remove();
}
}