How should I return the Primary Key of my table-read API requests without requiring a Primary Key on my table-write API requests? They use the same object.

I have a Person class and two controller functions.

public class Person {
    private Integer id; // this is the primary key in my table
    private String name;
    private Integer houseId;
    private Integer age;
}

@RestController
public class TestController {
    @RequestMapping("/")
    public List<Person> fetchAll() { // this function does a "SELECT *" on all rows
        return personDao.findAll();
    }

    @PostMapping(value = "/createPerson")
    public void createPerson(@RequestBody Person person) { // this function does an "INSERT"
        personDao.insertPerson(person);
    }
}

I don't want to require the table Primary Key (class attribute "id") on all my "createPerson" API requests, since the client won't know it. I want to skip on that value, and let the table increment the PK on insert.

However, I want to return the "id" in the "fetchAll" API requests. And I want it defined on the Person object.

I don't see a way to do this besides making "id" Optional type, or defining two separate objects: "PersonRequest" and "PersonResponse", both which will extend "Person" class. Both of which seems like a bad practice

Is there something I'm missing?

CodePudding user response：

Since you said that you want to have the id automatically incremented make sure to add the annotations below to your id field:

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

There is nothing stopping you from saving an object without an id even though it has a property id. If you do:

Person person = new Person(); //person is empty here
person = personRepository.save(person);

The return value assigned to person will have an id. Also when you execute:

Person person = personRepository.findById(id);

The person object will have the id, I am not sure what else is confusing you.