How to autogenerate created or modified timestamp field?

Question

My entity class:

@Entity
@Table(name = \"user\")
public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
           


        

Answer 1

You can go with Spring Data JPA, Spring has made it as easy using annotation @CreatedBy, @CreatedDate, @LastModifiedBy, @LastModifiedDate on your fields. You can follow below simple example

// Will need to enable JPA Auditing
@Configuration
@EnableJpaAuditing(auditorAwareRef = "auditorAware")
class JpaConfig {
    // Creating a bean of AuditorAwareImpl which will provide currently logged in user
    @Bean
    public AuditorAware auditorAware() {
        return new AuditorAwareImpl();
    }
}

// Moving necessary fields to super class and providing AuditingEntityListener entity listner class
@MappedSuperclass
@EntityListeners(AuditingEntityListener.class)
abstract class Auditable {

    @CreatedBy
    protected U createdBy;

    @CreatedDate
    @Temporal(TIMESTAMP)
    protected Date createdDate;

    @LastModifiedBy
    protected U lastModifiedBy;

    @LastModifiedDate
    @Temporal(TIMESTAMP)
    protected Date lastModifiedDate;

    // Getters and Setters
}

// Creating implementation of AuditorAware and override its methods to provide currently logged in user
class AuditorAwareImpl implements AuditorAware {

    @Override
    public String getCurrentAuditor() {
        return "Naresh";
        // Can use Spring Security to return currently logged in user
        // return ((User) SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getUsername()
    }
}

@Entity
class File extends Auditable {
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private String content;

    // Getters and Setters
} 

You can read more on my article Spring Data JPA Auditing: Saving CreatedBy, CreatedDate, LastModifiedBy, LastModifiedDate automatically for more details.