在spring boot jpa中的多对一映射中，外键未在子表中更新

Question

我创建了一个两个实体关系一对多（一个员工有多个地址）及其双向关系，如多对一。

@Entity

@Table(name = "Employees")

@EntityListeners(AuditingEntityListener.class)

public class Employee {

@Id

@GeneratedValue(strategy = GenerationType.AUTO)

@Column(name="employee_id")

private Long id;

@NotBlank

private String name;

@NotBlank

private String designation;

@Temporal(TemporalType.TIMESTAMP)

@LastModifiedDate

private Date createdAt;

@OneToMany(mappedBy = "employee", cascade = CascadeType.ALL)

private List<Address> employee_address;

和地址实体如下

    @Entity

@Table(name = "address")

public class Address {

    @Id

    @GeneratedValue(strategy = GenerationType.AUTO)

    private long address_id;

    @NotBlank

    @Column(name = "address_street", length = 250)

    private String street;

    @NotBlank

    @Column(name = "address_city", length = 50)

    private String city;

    @NotBlank

    @Column(name = "address_state", length = 50)

    private String state;

    @NotBlank

    @Column(name = "address_zipcode", length = 10)

    private String zipcode;

    @JsonIgnore

    @ManyToOne(cascade = CascadeType.ALL)

    @JoinColumn(name = "employee_id", nullable = false, referencedColumnName = "employee_id")

    private Employee employee;

和 EmployeeController 保存数据如下

@RestController

public class EmployeeController {

    @Autowired

    EmployeeDAO employeeDAO;

    @Autowired

    AddressDAO addressDAO;

    @PostMapping("/employees")

    public void createEmployee(@Valid @RequestBody Employee emp) {

        Address address = null;

        List<Address> listAddresses = new ArrayList<Address>();

        if (emp != null) {

            Employee employee = new Employee();

            employee.setDesignation(emp.getDesignation());

Answer 1

在定义关系时的休眠中，您拥有关系的拥有方。关系的拥有方是粗略说的持有@JoinColumn 映射的一方。当调用 update/remove/persist 时，所有这些操作都是通过拥有方执行的。拥有集合时，您需要维护集合的两端。当您向 Employee 添加新地址时，您需要确保该地址也具有对 Employee 的反向引用。您的 Employee 实体是您的关系的所有者。如果您有类别 - 项目关系，并且您将一个项目从一个类别移动到另一个类别。将 Item 从 category1 列表移动到 category2 列表是不够的，您还需要更改 Item 中的反向引用。

Answer 2

您需要取消注释该行：&nbsp;address.setEmployee(employee);在您的控制器中。这是因为您定义了这样的映射：@JsonIgnore@ManyToOne(cascade = CascadeType.ALL)@JoinColumn(name = "employee_id", nullable = false, referencedColumnName = "employee_id")private Employee employee;nullable = false表明，必须有来自Adressto的引用Emplyee。但是错误可能来自对数据库的约束，即该列不能为空。