仅发布单向多对一关系的ID

Question

I am submitting a POST request (JSON) to create a new instance of a Person and each Person has to have a Status associated with them. There is a prepopulated Status table that has a limited number of statuses. Is just submitting the entity id of the status the best approach here?

Currently, I submit just the id of the Status entity in my request, but this means loading a Status from the DB using the id and adding it to the transient Person before it's persisted beforehand to satisfy the JPA/DB constraints, but this is inefficient.

Request body (truncated for brevity) unmarshalled to PersonDTO:

{
    "name" : "Dave",
    "statusId" : "1",
    ::
}

Status entity

@Entity
public class Status {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;

    @Column
    private String status;
}

Person entity

@Entity
public class Person {

   @Id
   @GeneratedValue(strategy = GenerationType.SEQUENCE)
   private Long id;

    @ManyToOne(optional = false)
    @JoinColumn(name = "status_id")
    private Status status;
    ::

Is the best approach actually submitting the status object in the JSON request so I don't have to perform any sort of lookup on the status id?

{
    "name" : "Dave",
    "status" : {
      "id" : 1
      "status" : "AVAILABLE"
    },
    ::
}

I appreciate that I can preload the statuses at startup into a singleton so they are accessible or cache a service class method that returns a status using the id, but I am wondering what the best approach is here because if I was using native SQL I could just insert the Person into the database with a status id and not perform any lookup of the status beforehand.

Answer 1

1) Once you start using Native SQL, you will start using it in more and more places. Eventually, you will lose the database provider independence that JPA gives you. I am not saying it is 100% bad, I am just saying..

2) You can apply the second-level-cache for the Status as it seems to be a sort of dictionary table:

@Entity
@Cacheable

3) If you are not expecting to make any changes to the status object itself, you should load it not using the findById , which goes to the database, but use the getOne instead which only creates a reference and should be sufficient in your case.