Spring Data JDBC. Please tell me how to implement the isNew method of the Persistable interface

Question

I want the aggregate root element to control whether to do an update or an insert. Please tell me how to implement this in the isNew method.

@Data
public class State implements Persistable<String> {

    @Id
    private String id;
    private String name;


    public State(String id, String name){
        this.id=id;
        this.name=name;
    }


    @Override
    public boolean isNew() {
        return true;
    }
}

@SpringBootApplication
public class Isnew2Application {

    public static void main(String[] args) {
        SpringApplication.run(Isnew2Application.class, args);
    }

    @Bean
    CommandLineRunner runner(StateRepo stateRepo){
        return args -> {
            stateRepo.save(new State("ID","Idaho"));
            stateRepo.save(new State("IA","Iowa"));
            stateRepo.save(new State("AL","Alabama"));
            stateRepo.save(new State("AK","Alaska"));
        };
    }
}

When you run the code again, an exception is naturally thrown.

Answer 1

One way or another you need to change the isNew state of the entity. You can do it explicitly in your code, you cand do it in a life cycle callback, you can decide it based on the constructor use. See https://spring.io/blog/2021/09/09/spring-data-jdbc-how-to-use-custom-id-generation/ for various options and how to implement them.