Error in @Onetomany mapping with JPA and Hibernate

Question

At the moment, I’m having a problem with mapping @OneToMany/@ManyToOne in my application. I would like it when I persist my entity Sale automatically save the sale items in single shot.

@Entity
@Table(name = "sale")
public class Sale implements Serializable {

    private static final long serialVersionUID = -3857608619547245492L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @Column(name = "company", nullable = false)
    private Long company;


    @JsonIgnore
    @OneToMany(mappedBy = "sale", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<SaleItem> saleItems = new ArrayList<>();

    public Sale() {
    }

    public void addSaleItem(SaleItem saleItem) {
       getSaleItems().add(saleItem);
       saleItem.setSale(this);
    }

    //****************************Getters and Setters****************************

}



@Entity
@Table(name = "sale_item")
public class SaleItem implements Serializable {

    private static final long serialVersionUID = 1016354254590870341L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @Column(name = "company", nullable = false)
    private Long company;    

    @Column(name = "description", nullable = false)
    private String description;

    @Column(name = "amount", nullable = false)
    private Double amount;

    @Column(name = "price", nullable = false)
    private Double price;

    @ManyToOne(fetch = FetchType.LAZY)
    private Sale sale;

    public SaleItem() {

    }

    //**************************** SEM SALE Getters e Setters ****************************





    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (!(o instanceof SaleItem))
            return false;
        return id != null && id.equals(((SaleItem) o).getId());
    }

    @Override
    public int hashCode() {
        return 31;
    }   

    @Override
    public String toString() {
        return "SaleItem [id=" + id + ", company=" + company + ", product=" + product + ", created=" + created
                + ", updated=" + updated + ", description=" + description + ", amount=" + amount + ", price=" + price
                + ", discount=" + discount + ", user=" + user + ", unit=" + unit + ", sale=" + sale + "]";
    }


}

    //*********************** My Controller ***********************

    /**
     * Create Sale
     * 
     * @param sale
     * @param result
     * @return ResponseEntity<Response<SaleDto>>
     * @throws ParseException
     */
    @PostMapping
    public ResponseEntity<Response<SaleDto>> create(@Valid @RequestBody SaleDto saleDto, BindingResult result)
            throws ParseException {

        log.info("Creating sale: {}", saleDto.toString());
        Response<SaleDto> response = new Response<SaleDto>();

        validateSale(saleDto, result);

        if (result.hasErrors()) {
            log.error("Error - invalid information for Sale: {}", result.getAllErrors());
            result.getAllErrors().forEach(error -> response.getErrors().add(error.getDefaultMessage()));
            return ResponseEntity.badRequest().body(response);
        }

        response.setData(this.convertSaleDto(this.nova(saleDto, result)));
        return ResponseEntity.ok(response);
    }

    private Sale nova(SaleDto saleDto, BindingResult result) throws ParseException {

       Sale sale = new Sale();
       sale.setCompany(saleDto.getCompany());
       sale.setUser(saleDto.getUser());
       sale.setType(TypeSales.valueOf(saleDto.getType()));
       sale.setDescription(saleDto.getDescription());
       sale.setValue(saleDto.getValue());
       sale.setSubValue(saleDto.getSubValue());
       sale.setDiscount(saleDto.getDiscount());


       for (int i = 0; i < saleDto.getItems().size(); i++) {
           SaleItem saleItem = new SaleItem();
           saleItem.setCompany(saleDto.getCompany());
           saleItem.setUser(saleDto.getUser());
           saleItem.setProduct(saleDto.getItems().get(i).getProduct());
           saleItem.setAmount(saleDto.getItems().get(i).getAmount());
           saleItem.setPrice(saleDto.getItems().get(i).getPrice());
           saleItem.setDescription(saleDto.getItems().get(i).getDescription());
           saleItem.setDiscount(saleDto.getItems().get(i).getDiscount());
           saleItem.setUnit(saleDto.getItems().get(i).getUnit());
           sale.addSaleItem(saleItem);
       }

       return this.saleService.persist(sale);
    }



    //**************************My Service**************

    /**
     * Persist a sale
     * 
     * @param Sale
     * @return Sale
     */
    Sale persist(Sale sale);



//******************My impl***********************
@Transactional
public Sale persist(Sale sale) {
    log.info("Persisting sale {}", sale);
    return this.saleRepository.save(sale);
}

The problem that is only saving the entity Sale leaving items blank at all times.

Answer 1

In this case you can use a one-way relationship:

@Entity
@Table(name = "sale")
public class Sale implements Serializable {

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

   @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
   @JoinColumn(name = "sale_id")
   private List<SaleItem> saleItems = new ArrayList<>();

   public List<SaleItem> getSaleItems() {
        return saleItems;
   }


}

@Entity
@Table(name = "sale_item")
public class SaleItem implements Serializable {

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

   // deve remover a classe Sale desse lado
} 

To insert an item you can use, for example:

public void addSaleItem(SaleItem saleItem) {
   getSaleItems().add(item);
}

http://blog.triadworks.com.br/jpa-por-que-voce-deveria-evitar-relacionamento-bidirecional

Answer 2

When the relationship is bidirectional, you should connect the two sides of the relationship explicitly:

private Sale nova(SaleDto saleDto, BindingResult result) throws ParseException {
    SaleItem saleItem = new SaleItem();
    saleItem.setCompany(saleDto.getCompany());
    saleItem.setPrice(saleDto.getItems().get(0).getPrice());
    saleItem.setDescription(saleDto.getItems().get(0).getDescription());
    saleItem.setUnit(saleDto.getItems().get(0).getUnit());

    Sale sale = new Sale();
    sale.setCompany(saleDto.getCompany());
    sale.setUser(saleDto.getUser());
    sale.addSaleItem(saleItem);
    saleItem.setSale(sale);   // <-- Isso é muito importante de se fazer.

    return this.saleService.persist(sale);
}