如何使用hibernate创建具有现有对象的复合键对象

Question

假设我有以下数据库架构

CREATE TABLE employee(
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    hrid VARCHAR (50)
);
CREATE TABLE territory(
    id BIGINT PRIMARY KEY,
    name varchar (50)
);
CREATE TABLE transcode(
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    code VARCHAR (10) NOT NULL
);
create table employee_territory_function(
  employee_id BIGINT NOT NULL,
  territory_id BIGINT NOT NULL,
  transcode_id BIGINT NOT NULL,
  PRIMARY KEY (employee_id,territory_id),
  CONSTRAINT employeeref FOREIGN KEY (employee_id) REFERENCES employee (id),
  CONSTRAINT territoryref FOREIGN KEY (territory_id) REFERENCES territory (id) ,
  CONSTRAINT transcoderef FOREIGN KEY (transcode_id) REFERENCES transcode (id)
);

现在我有以下 JPA 映射实体

员工实体

@Entity
public class Employee implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;
    private String hrid;
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "employee", cascade = CascadeType.ALL)
    private Set<EmployeeTerritoryFunction> employeeTerritoryFunctionList = new HashSet<>();
    //getters and setters
}

领土实体：

@Entity
public class Territory implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;

    // getters and setters for all field

}

转码实体：

@Entity
public class Territory implements Serializable {
    @Id
    private long id;
    private String name;
    //getters and setters
}

EmployeeTerritoryFunction 实体（复合键表）

@Entity
@IdClass(value = EmployeeTerritoryFunctionPK.class)
public class EmployeeTerritoryFunction implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @ManyToOne
    private Employee employee;

    @Id
    @ManyToOne
    private Territory territory;

    @ManyToOne
    @JoinColumn(name = "transcode_id", referencedColumnName = "id")
    private Transcode transcode;
    //getters and setters
}

EmployeeTerritoryFunction pk

public class EmployeeTerritoryFunctionPK implements Serializable {
    private static final long serialVersionUID = 1L;

    private Long employee;
    private Long territory;
    //getters and setters, no args constructor, equals and hashcode
}

样本插入下方

Employee employee = this.employeeRepository.findByHrid("111");
        if (employee == null) {
            employee = new Employee();
            employee.setName("Marie");
            employee.setHrid("333");
        }

        Territory territory = new Territory();
        territory.setId(2L);
        territory.setName("T2");

        Territory territory2 = new Territory();
        territory2.setId(3L);
        territory2.setName("T3");


        Transcode transcode = this.transcodeRepository.findByCode("ASC");
        Transcode transcode2 = this.transcodeRepository.findByCode("CC");


        EmployeeTerritoryFunction employeeTerritoryFunction1 = new EmployeeTerritoryFunction();

        employeeTerritoryFunction1.setTranscode(transcode);
        employeeTerritoryFunction1.setTerritory(territory);
        employeeTerritoryFunction1.setEmployee(employee);
        employee.getEmployeeTerritoryFunctionList().add(employeeTerritoryFunction1);

        EmployeeTerritoryFunction employeeTerritoryFunction2 = new EmployeeTerritoryFunction();
        employeeTerritoryFunction2.setTranscode(transcode2);
        employeeTerritoryFunction2.setTerritory(territory2);
        employeeTerritoryFunction2.setEmployee(employee);
        employee.getEmployeeTerritoryFunctionList().add(employeeTerritoryFunction2);

        employeeRepository.save(employee);

当我只使用新对象运行上面的代码时，我没有问题，因为 hibernate 会自动插入员工、区域和employee_territory_function 列表，但是当我第一次删除所有现有区域时，employee_territory_function 并尝试使用现有员工插入， hibernate 不能自动插入或更新员工、自动插入区域、employee_territory_function。 下面的错误

Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.demo.Employee.employeeTerritoryFunctionList, could not initialize proxy - no Session

当我将 oneToMany 提取类型替换为 EAGER 时，出现以下错误

Caused by: javax.persistence.EntityNotFoundException: Unable to find com.example.demo.Territory with id 3

hibernate 尝试查询 Territory 表的接缝，但我不这样做，因为我删除了 Territory 和 EmployeeTerritoryFunction 表上的所有数据，并且只有员工现有数据没有被删除。

请问如何解决？

Answer 1

EmployeeTerritoryFunction 和 EmployeeTerritoryFunctionPK 两个类中的字段应命名完全相同，并且具有您没有的相同类型。试试这样：

@Entity
@IdClass(EmployeeTerritoryFunctionPK.class)
public class EmployeeTerritoryFunction implements Serializable {

    @Id
    @ManyToOne
    private Employee employee;

    @Id
    @ManyToOne
    private Territory territory;
}

public class EmployeeTerritoryFunctionPK implements Serializable {
    private Employee employee;
    private Territory territory;

    public int hashCode() { //TODO }
    public boolean equals(Object obj) { //TODO }

}