我創(chuàng)建了一個(gè)兩個(gè)實(shí)體關(guān)系一對(duì)多（一個(gè)員工有多個(gè)地址）及其雙向關(guān)系，如多對(duì)一。@Entity@Table(name = "Employees")@EntityListeners(AuditingEntityListener.class)public class Employee {@Id@GeneratedValue(strategy = GenerationType.AUTO)@Column(name="employee_id")private Long id;@NotBlankprivate String name;@NotBlankprivate String designation;@Temporal(TemporalType.TIMESTAMP)@LastModifiedDateprivate Date createdAt;@OneToMany(mappedBy = "employee", cascade = CascadeType.ALL)private List<Address> employee_address;和地址實(shí)體如下 @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 保存數(shù)據(jù)如下@RestControllerpublic 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());
2 回答
鳳凰求蠱
TA貢獻(xiàn)1825條經(jīng)驗(yàn) 獲得超4個(gè)贊
在定義關(guān)系時(shí)的休眠中，您擁有關(guān)系的擁有方。關(guān)系的擁有方是粗略說(shuō)的持有@JoinColumn 映射的一方。當(dāng)調(diào)用 update/remove/persist 時(shí)，所有這些操作都是通過(guò)擁有方執(zhí)行的。擁有集合時(shí)，您需要維護(hù)集合的兩端。
當(dāng)您向 Employee 添加新地址時(shí)，您需要確保該地址也具有對(duì) Employee 的反向引用。您的 Employee 實(shí)體是您的關(guān)系的所有者。
如果您有類(lèi)別 - 項(xiàng)目關(guān)系，并且您將一個(gè)項(xiàng)目從一個(gè)類(lèi)別移動(dòng)到另一個(gè)類(lèi)別。將 Item 從 category1 列表移動(dòng)到 category2 列表是不夠的，您還需要更改 Item 中的反向引用。
森欄
TA貢獻(xiàn)1810條經(jīng)驗(yàn) 獲得超5個(gè)贊
您需要取消注釋該行：
address.setEmployee(employee);
在您的控制器中。
這是因?yàn)槟x了這樣的映射：
@JsonIgnore
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "employee_id", nullable = false, referencedColumnName = "employee_id")
private Employee employee;
nullable = false表明，必須有來(lái)自Adressto的引用Emplyee。但是錯(cuò)誤可能來(lái)自對(duì)數(shù)據(jù)庫(kù)的約束，即該列不能為空。
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