Hiberanate未能保存加入专栏

Question

每当我创建新商家时，我都会尝试保存公司的董事名单，因此我分别在Director和Merchant之间建立了@ManyToOne关系。

到目前为止，我在设置POST时设法保存了导演和商家列表。但是当我做GET请求时我没有找回导演，列表又回来了。当我签入数据库时​​，加入列为空，如图所示，但其余数据存在。我该如何解决这个问题？

这是我的代码：

Director.java

@Entity
@Table(name = "Directors")
public class Director {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long directorID;

@Cascade({org.hibernate.annotations.CascadeType.ALL}) 
@ManyToOne
@JoinColumn(name = "merchantNumber")
private Merchant merchant;

@NotBlank
private String name;

@NotBlank
private String surname;

 public Director() {

    }

public Director(long directorID, Merchant merchant, String name, String surname) {
    this.directorID = directorID;
    this.merchant = merchant;
    this.name = name;
    this.surname = surname;
}

...

Getters and setters

DirectorRepository.java

public interface DirectorRepository  extends CrudRepository<Director, String> {

}

Merchant.java

public class Merchant {
 @Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int merchantNumber;

@NotBlank
private String merchantID;

@NotBlank
private String businessName;

@Cascade({org.hibernate.annotations.CascadeType.ALL}) 
@OneToMany(mappedBy = "merchant")
 private List<Director> directors;

@NotBlank
private String userName;



public Merchant(int merchantNumber, String merchantID, String businessName, List<Director> directors, String userName ) {
        this.merchantNumber = merchantNumber;
        this.merchantID = merchantID;
        this.businessName = businessName;
        this.directors = directors;
        this.userName = userName;
    }

    ...

    Getter and setters

MerchantService.java

   public ResponseMerchantQuery createMerchant(Merchant merchant) {

           if( merchant == null || merchant.getMerchantID()== null){
              throw new ResourceNotFoundException("Empty", "Missing Data Exception");
          } else {
              merchant.setPassword(passwordEncoder.encode(merchant.getPassword()));
              merchantRepository.save(merchant);
              String merchantNum = Long.toString(merchant.getMerchantNumber());
              return new ResponseMerchantQuery(merchantNum, "Merchant Created Successfully");
          }
    }

MerchantController.java

    @RequestMapping(method = RequestMethod.POST, value = "/api/merchants")
    public ResponseMerchantQuery createMerchant(@Valid @RequestBody Merchant merchant){

     System.out.println("size of merchnat " + merchant.getDirectors().size());
       return  merchantService.createMerchant(merchant);

     }