Spring Data MongoDB #Transactional isn't working? - spring-data

Question

I have below maven dependency & configuration set up
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
#Configuration
#EnableMongoAuditing
public class MongoConfig {
#Bean
MongoTransactionManager transactionManager(MongoDbFactory mongoDbFactory) {
return new MongoTransactionManager(mongoDbFactory);
}
}
Updated: I've taken the suggested solution to create a bean with #Transactional, and have it injected into my test class. Below is the service bean I created:
#Service
#Transactional
#RequiredArgsConstructor
public class MongoTransactionService {
private final UserRepo userRepo;
public void boundToFail() throws RuntimeException {
userRepo.save(User.builder().id("1").build());
throw new RuntimeException();
}
}
and test class where I inject a bean of MongoTransactionService:
#DataMongoTest(excludeAutoConfiguration = EmbeddedMongoAutoConfiguration.class,
includeFilters = #ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = MongoTransactionService.class))
#ExtendWith(SpringExtension.class)
class MongoTransactionServiceTest {
#Autowired
UserRepo userRepo;
#Autowired
MongoTransactionService mongoTransactionService;
#Test
void testTransactional() {
try {
mongoTransactionService.boundToFail();
} catch (Exception e) {
// do something
}
val user = userRepo.findById("1").orElse(null);
assertThat(user).isNull();
}
}
I am expecting a call to boundToFail(), which throws a RuntimeException, would roll back the saved user, but the user still gets persisted in the database after the call.

Answer 1

It turns out that #DataMongoTest doesn't activate the auto-configuration for MongoDB transactions. I've filed a ticket with Spring Boot to fix that. In the mean time, you can get this to work by adding
#ImportAutoConfiguration(TransactionAutoConfiguration.class)
to your test class.
Note that using MongoDB transactions requires a replica set database setup. If that's not given the creation of a transaction will fail and your test case will capture that exception and the test will still succeed. The data will not be inserted but that's not due to the RuntimeException being thrown but the transaction not being started in the first place.
The question previously presented a slightly different code arrangement that suffered from other problems. For reference, here's the previous answer:
#Transactional needs to live on public methods of a separate Spring bean as the transactional logic is implemented by wrapping the target object with a proxy that contains an interceptor interacting with the transaction infrastructure.
You example suffers from two problems:
The test itself is not a Spring bean. I.e. there's no transactional behavior added to boundToFail(…). #Transactional can be used on JUnit test methods but that's controlling the transactional behavior of the test. Most prominently, to roll back the transaction to make sure changes to the data store made in the test do not affect other tests. See this section of the reference documentation.
Even if there was transactional logic applied to boundToFail(…), a local method call to the method would never trigger it as it doesn't pass the proxy that's applying it. See more on that in the reference documentation.
The solution to your problem is to create a separate Spring bean that carries the #Transactional annotation, get that injected into your test case and call the method from the test.