使用复合键的许多人：如何在实体之间的表中添加元素？

Question

所以我一直在关注本教程https://www.baeldung.com/jpa-many-to-many

我希望不同的VendingMachines为不同种类的品牌拥有不同种类的库存。到目前为止，遵循本教程并打开H2控制台似乎表结构是正确的。但是，我无法管理如何向结合了两个实体的表中添加内容。我的意思是，增加了自动售货机，增加了品牌，但无法增加库存。

我有

@Entity
public class VendingMachine {
    @Id @GeneratedValue Long vendingMachineid;
    String model;
    int maxBrandsAvailable;
    int maxStockperBrand;
    @OneToMany(mappedBy="vendingMachine")
    @JsonIgnore
    private Set<BrandStock> brandstock;

@Entity
public class Brand {

    @Id @GeneratedValue long brandId;
    String name;
    double price;
    @OneToMany(mappedBy = "brand")
    @JsonIgnore
    Set<BrandStock> brandStock;

我也有两个实体的Jpa存储库。

与不同品牌相关的每台自动售货机的存货

@Entity
public
class BrandStock {

    @EmbeddedId
    BrandStockKey id;

    @ManyToOne
    @MapsId("brand_id")
    @JoinColumn(name = "brand_id")
    Brand brand;

    @ManyToOne
    @MapsId("vendingMachine_id")
    @JoinColumn(name = "vendingMachine_id")
    VendingMachine vendingMachine;

    private int stock;

当然还有该表的主键生成器

@Embeddable
class BrandStockKey implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column(name = "brand_id")
    Long brandId;

    @Column(name = "vendingMachine_id")
    Long vendingMachineId;

在CommandLineRunner上，我用来添加元素的方法看起来像这样，`]

    BrandStock cocaColaForModel01 = new BrandStock();
    Set<BrandStock> stockForModel01 = new HashSet<BrandStock>();
    VendingMachine model01=new VendingMachine("Model01", 5, 10,null);
    stockForModel01.add(cocaColaForModel01);
    cocaColaForModel01.setStock(10);
    cocaColaForModel01.setVendingMachine(model01); 
    Brand cocaCola = new Brand("CocaCola", 1.75, stockForModel01);

    model01.setBrandstock(stockForModel01);
    cocaCola.setBrandStock(stockForModel01);

    brandRepository.save(cocaCola);    
    vendingMachineRepository.save(model01);

因此，我一直在关注本教程https://www.baeldung.com/jpa-many-to-many，我希望不同的VendingMachines对于不同种类的品牌拥有不同种类的库存。到目前为止......>