I have a small service on SpringBoot and Mongodb as a DB. I need to be able create a small collection with one document ( very basic: id, name, status) on startup. An analog of sql create table if not exists, but for mongo. How do I do that? I tried to initialize values in the document attributes, but it didn't help. Currently, collection and the document appear only if I use API to add it.
2 Answers
You may want to use something like ApplicationRunner or CommandLineRunner which can be defined as a bean.
Example:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication .class, args);
}
@Bean
public CommandLineRunner initialize(MyRepository myRepository) {
return args -> {
// Insert elements into myRepository
};
}
}
Both CommandLineRunner and ApplicationRunner are functional interfaces, so we can use a lambda for them. Spring Boot will execute them at the startup of the application.
Comments
You can leverage the spring internal event mechanism.
When your application is ready, spring triggers the event ApplicationReadyEvent
You can listen to this event and init your collection:
@Component
public class DataInit implements ApplicationListener<ApplicationReadyEvent> {
private final MyRepository myRepository;
public DataInit(MyRepository myRepository) {
this.myRepository = myRepository;
}
@Override
public void onApplicationEvent(ApplicationReadyEvent event) {
// init data
}
}
Comments
