How to make a unique variable in REST web service in Java?

Question

I'm trying to make simple REST Web Service by Spring Boot in IntelliJ. I also have to make the CRUD client for that but that later.

I have to make a Products table with fields: id, name, price and status. And I have a problem with making a unique "name" field. If I send a data by postman with the same name it shouldn't add it to the database and should give me an server error.

Also I have to make that "status" field can only have 3 unique values: "available", "out of stock" and "withdrawn from sale". You can not add a new product with the status "withdrawn from sale". So you can use only those three values to post "status" data.

Could anyone help me with this?

My Products class:

@Entity
public class Products {
    private Long id;
    private String nazwa;
    private Float cena;
    private String status;

    @Id
    @GeneratedValue
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getNazwa() {
        return nazwa;
    }

    public void setNazwa(String nazwa) {
        this.nazwa = nazwa;
    }

    public Float getCena() {
        return cena;
    }

    public void setCena(Float cena) {
        this.cena = cena;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }
}

My ProductsController

@RestController
@RequestMapping("/products")
public class ProductsController {
@Autowired
private ProductJpaRepository productJpaRepository;

    @GetMapping(value = "/all")
    public List<Products> findAll() {
        return productJpaRepository.findAll();
    }

    @GetMapping(value = "/{nazwa}")
    public Products findByName(@PathVariable final String nazwa) {
        return productJpaRepository.findByNazwa(nazwa);
    }

    @PostMapping(value = "/load")
    public Products load(@RequestBody final Products products) {
        return productJpaRepository.save(products);
    }
}

Define an enum and have the member be of that type. – daniu May 13 '18 at 20:51 — daniu, May 13 '18 at 20:51

score 0 · Answer 1 · answered May 14 '18 at 06:03

I have to make that "status" field can only have 3 unique values: "available", "out of stock" and "withdrawn from sale".

You define an enum

public enum Status {
    AVAILABLE, OUT_OF_STOCK, WITHDRAWN
}

and use it in the Product instead of a String.

public class Product {
    private Long id;
    private String nazwa;
    private Float cena;

    private Status status;
    // ...
}

You do have to add some logic to get that into your repository, see eg JPA enumerated types mapping.

How to make a unique variable in REST web service in Java?

1 Answers1