Spring JPA 使用自定义查询 @Query 从关联实体公开/映射 @JsonIgnore 字段

Question

我有 2 个具有双向一对多关系的实体（部门、员工）。 1个部门有很多员工。 Department拥有Employee

我用@JsonIgnore注释了department字段，以便在我GET localhost:8080/employee时不会序列化Department信息

我创建了一个自定义查询来公开Employee的所有信息，包括员工所属的Department 。

部门Model

@Entity
public class Department {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String departmentName;

    @OneToMany(mappedBy = "department")
    private Set<Employee> employees;
   ...
}

员工Model

@Entity
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String firstName;
    private String middleName;
    private String lastName;

    @ManyToOne
    @JsonIgnore
    private Department department;
    ...
}

存储库

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {

    @Query(value = "SELECT e.*, d.department_name FROM Employee e INNER JOIN Department d ON e.department_id = d.id WHERE e.id = ?1", nativeQuery = true)
    Employee findEmployeeByIdWithDepartment(Long employeeId);
}

该查询在 H2-Console SQL 编辑器中运行良好。 如果我执行GET localhost:8080/employee/1 ，则会包含DEPARTMENT_ID ， DEPARTMENT_NAME信息

但是，在 Postman 中，我只获取Employee信息（id、firstname、lastname、middlename）。 Employee所属的Department没有被映射/序列化（因为我在Employee类中使用@JsonIgnored ）。

{
    "id": 1,
    "firstName": "John",
    "middleName": "Doe",
    "lastName": "Johnny"
}

如果我将Object findEmployeeByIdWithDepartment我可以获得Employee信息以及员工所属的Department 。

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {

    @Query(value = "SELECT e.*, d.department_name FROM Employee e INNER JOIN Department d ON e.department_id = d.id WHERE e.id = ?1", nativeQuery = true)
    Object findEmployeeByIdWithDepartment(Long employeeId);
}

结果：（不是嵌套Department信息的所需 JSON 格式）

[
    1,
    "John",
    "Johnny",
    "Doe",
    1,
    "Accounting"
]

如果我执行GET localhost:8080/employee/1并且仍然能够毫无问题地执行GET localhost:8080/department ，我不确定如何能够显示Department信息和Employee信息。

如果department字段 IN Employee class 中没有@JsonIgnore ，则 Json 响应将导致 StackOverflow 或 Endless 嵌套序列化问题。

谢谢你。

Answer 1

您可以为 Employee 中的 Depertment-properties 编写 getter，例如

@Entity
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String firstName;
    private String middleName;
    private String lastName;

    @ManyToOne
    @JsonIgnore
    private Department department;

    @JsonProperty("departmentId")
    public Long getDepartmentId()
    {
        return department.getId;
    }

    @JsonProperty("departmentName")
    public String getDepartmentName()
    {
        return department.getName();
    }

    ...

}