如何使用 REST API - Spring 引导插入带有伪造密钥的数据

Question

I've created my REST API that connect with my MYSQL database. It supports GET, PUT, DELETE and POST methods. Everything works fine, but when I'm trying to POST data to a table that contain forgein key I get:

Caused by: java.sql.SQLIntegrityConstraintViolationException: Column 'id_companies' cannot be null

I'm trying to POST data using Postman(through body or/and JSON raw)

I've seen similar problems on the Inte.net but I didn't find a solution to my specific problem.
I'm Using maven and lombok.

Entity User:

@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "users")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_users")
    private Integer idUser;
    @Column(name = "first_name")
    private String firstName;
    @Column(name = "last_name")
    private String lastName;
    @Column(name = "phone_number")
    private String phoneNumber;

    @ManyToOne(targetEntity = Company.class)
    @JsonBackReference(value = "companyUsers")
    @JoinColumn(name = "id_companies")
    private Company companies;
}

UserRepository:

@RepositoryRestResource(collectionResourceRel = "users", path = "users")
    public interface UserRepository extends PagingAndSortingRepository<User, Integer> {
}

Entity Company:

@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Entity
@Table(name = "companies")
public class Company implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id_companies")
    private Integer idCompany;
    @Column(name = "name")
    private String name;
    @Column(name = "nip")
    private String nip;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "companies")
    @JsonManagedReference(value = "companyUsers")
    private Set<User> users;
}

CompanyRepository:

@RepositoryRestResource(collectionResourceRel = "companies", path = "companies")
    public interface CompanyRepository extends PagingAndSortingRepository<Company, Integer> {
}

---EDITED---

sample data I am trying to add via Postman POST

Trying to create user with id_companies = 2(I'm sure it exists in my batabase)

{
    "id_users": 7,
    "firstName": "Joe",
    "lastName": "Doe",
    "phoneNumber": "565345765",
    "id_companies": 2,
}

I've tried POSTing it without "id_users" because its AUTO_INCREMENT, but the same problem keeps happening.

Answer 1

As far I understand You may have done wrong in your controller class.

If you want to create a user when posting your entity. At first, you have to save your user in your controller class.

company.setUsers(userRepository.save(company.getUser));
return companyRepository.save(company);

If you want to use existing users then you have to load user using id in your controller.