Spring boot - Entity : How to add CreatedDate (UTC timezone aware), LastModifiedDate (UTC timezone aware), CreatedBy, LastModifiedBy

Question

I am new to Spring boot. I am planning to use postgresql database. I am using spring data JPA

In this entity, I need to add these fields

@Entity
@Table(name="STUDENT")
public class Student {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    
    @Column(name="STUDENT_NAME", length=50, nullable=false, unique=false)
    private String name;

    Here i want to add
    createdby, modifiedby <--
   
    createdat, modifiedat <-- (i want them to be timezone aware)
    
    // other fields, getters and setters
}

How can i do this.

I am coming from django background there we just do there

class Student(models.Model):

   ... other fields
   created_at = models.DateTimeField(auto_now_add=True)
   updated_at = models.DateTimeField(auto_now=True)
   created_by = models.ForeignKey(User,related_name="%(app_label)s_%(class)s_created_by",on_delete=models.CASCADE)

Answer 1

You can use the @PrePersist and @PreUpdate methods. For example:

@Entity
public class SomeEntity {

    //..other properties..//

    private LocalDateTime createDate;
    private LocalDateTime modifyDate;
    private String createdBy;
    private String modifiedBy;

    @PrePersist
    private void beforeSaving() {
        createDate = LocalDateTime.now();
        createdBy = Thread.currentThread().getName(); //todo: put your logic here
    }

    @PreUpdate
    private void beforeUpdating() {
        modifyDate = LocalDateTime.now();
        modifiedBy = Thread.currentThread().getName(); //todo: put your logic here
    }
}

Additionally, if you wanna use such methods in all of your entities you can create BaseEntity and extend it in other classes, for example:

@MappedSuperclass
public class BaseEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private LocalDateTime createDate;
    private LocalDateTime modifyDate;
    private String createdBy;
    private String modifiedBy;

    @PrePersist
    private void beforeSaving() {
        createDate = LocalDateTime.now();
        createdBy = Thread.currentThread().getName(); //todo: put your logic here
    }

    @PreUpdate
    private void beforeUpdating() {
        modifyDate = LocalDateTime.now();
        modifiedBy = Thread.currentThread().getName(); //todo: put your logic here
    }

    //..getters/setters omitted..//
}

and

@Entity
public class SomeEntity extends BaseEntity{
    //..other properties..//
}