无法覆盖onBeforeConvert：“......有相同的删除，但都没有覆盖其他”

Question

I've been trying but failing to imitate a Baeldung article 's walkthrough on how to trigger a save on a "child": an entity that is "contained" in another via Spring Boot's @DBRef annotation. In my case, I'm trying to DBRef an Address (child) from a Customer.

I'm posting my brief configuration file as well as the suspect code because I don't know if it is malformed.

The code that I suspect is erroneous is in a class called "CustomerCascadeSaveMongoEventListener.java" under src > main > java > foo.bar, and looks like:

@Override
public class CustomerCascadeSaveMongoEventListener extends AbstractMongoEventListener {
    @Autowired
    private MongoOperations mongoOperations;

    @Override
    public void onBeforeConvert(BeforeConvertEvent<Object> event) {
        Object source = event.getSource();
        if ((source instanceof Customer) && (((Customer) source).getAddress() != null)) {
            mongoOperations.save(((Customer) source).getAddress());
        }
    }
}

IntelliJ red-squiggles the @Override for not overriding and the method signature for the same reason as the error message.

For lack of knowing what else to call it, my XML file is called "cascade.properties", is under src > main > java > foo.bar > resources, and looks like:

<mongo:mongo-client id="mongoClient" host="localhost" />
<mongo:db-factory id="mongoDbFactory" dbname="test" mongo-ref="mongoClient" />
<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate"> 
    <constructor-arg ref="mongoDbFactory"/> 
</bean>
<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>
<bean class="org.baeldung.event.CustomerCascadeSaveMongoEventListener" />

Finally, inside my Customer class, the field referencing the address looks like:

    @DBRef
    @NotNull
    private Address address;

The main error message is as follows:

Error:(16, 17) java: name clash: onBeforeConvert(org.springframework.data.mongodb.core.mapping.event.BeforeConvertEvent) in io.catalyte.training.CustomerCascadeSaveMongoEventListener and onBeforeConvert(org.springframework.data.mongodb.core.mapping.event.BeforeConvertEvent) in org.springframework.data.mongodb.core.mapping.event.AbstractMongoEventListener have the same erasure, yet neither overrides the other

I think solving that problem would also eliminate the second error message:

Error:(15, 5) java: method does not override or implement a method from a supertype

While my configuration file may well have nothing to do with the error(s), I would appreciate pointers if anything about its contents will not support or is unnecessary for the cascading save behavior I'm going for. So far, it's contents were written only with the intent of supporting this functionality.

Answer 1

Though it's unlikely anyone else is going to have exactly this issue, for posterity:

As one could have guessed, there was nothing wrong with Baeldung's code, just how I copied it. My mistakes were two, both having to do with the class signature. It should have looked like this:

public class CustomerCascadeSaveMongoEventListener extends AbstractMongoEventListener<Object> {

without the annotation I gave it.

Also for posterity, Java config files like MongoConfig are often in the main package in a sub-package called "config". To get this functionality to work, my MongoTransactionConfig file looked like this:

@Configuration
@EnableMongoRepositories(basePackages = "io.catalyte.training.repositories")
public class MongoTransactionConfig extends AbstractMongoConfiguration {
    @Bean
    public CustomerCascadeSaveMongoEventListener customerCascadingMongoEventListener() {
        return new CustomerCascadeSaveMongoEventListener();
    }

    @Bean
    MongoTransactionManager transactionManager(MongoDbFactory dbFactory) {
        return new MongoTransactionManager(dbFactory);
    }

    @Override
    protected String getDatabaseName() {
        return "test";
    }

    @Override
    public MongoClient mongoClient() {
        return new MongoClient("127.0.0.1", 27017);
    }
}

though you or your IDE will need to provide the appropriate package and import statements.