Hibernate: cố gắng gán id từ vô sở hữu one-to-one: nhân viên

Question

này được cấu trúc cơ sở dữ liệu của tôi, One-to-One lập bản đồ trong MySQL:

Đây chính là file java của tôi:

public class Employee { 

private EmployeeDetail empdetail; 
private String firstname; 
private String lastname; 

// getters and setters 

} 


public class EmployeeDetail { 
    private Employee employee ; 
    private int employee_id; 
    private String street; 
    private String city; 
    private String state; 
    private String country; 

// getters and setters 

} 

Đây là tập tin bản đồ của tôi:

<hibernate-mapping> 

    <class name="Employee" table="employee"> 
     <id name="employee_id" type="java.lang.Integer" column="employee_id"> 
      <generator class="assigned" /> 
     </id> 
     <one-to-one name="empdetail" class="EmployeeDetail" 
      cascade="all"></one-to-one> 

     <property name="firstname" type="java.lang.String" column="firstname" /> 
     <property name="lastname" type="java.lang.String" column="lastname" /> 

    </class> 



<class name="EmployeeDetail" table="employeedetail"> 
     <id name="employee_id" type="java.lang.Integer" column="employee_id"> 
     <generator class="foreign"> 
       <param name="property">employee</param> 
      </generator> 
     </id> 
     <one-to-one name="employee" class="Employee" 
      cascade="save-update"></one-to-one> 

     <property name="street" type="java.lang.String" column="street" /> 
     <property name="city" type="java.lang.String" column="city" /> 
     <property name="state" type="java.lang.String" column="state" /> 
     <property name="country" type="java.lang.String" column="country" /> 

</class> 

</hibernate-mapping> 

Đây là chương trình khách hàng của tôi:

Session session = factory.openSession(); 
     Transaction tx = session.beginTransaction(); 

     EmployeeDetail edetail = new EmployeeDetail(); 
     edetail.setCity("Hyd"); 
     edetail.setCountry("India"); 
     edetail.setEmployee_id(222); 
     edetail.setState("Andhra Pradesh"); 

     Employee employee = new Employee(); 

     employee.setEmployee_id(222); 
     employee.setFirstname("Pavan"); 
     employee.setLastname("Jaooi"); 
     employee.setEmpdetail(edetail); 

     session.merge(employee); 
     tx.commit(); 
     session.close(); 
     factory.close(); 

Đây là ngoại lệ Tôi nhận:

INFO: Not binding factory to JNDI, no JNDI name configured 
Hibernate: select employee0_.employee_id as employee1_0_1_, employee0_.firstname as firstname0_1_, employee0_.lastname as lastname0_1_, employeede1_.employee_id as employee1_1_0_, employeede1_.street as street1_0_, employeede1_.city as city1_0_, employeede1_.state as state1_0_, employeede1_.country as country1_0_ from employee employee0_ left outer join employeedetail employeede1_ on employee0_.employee_id=employeede1_.employee_id where employee0_.employee_id=? 
Hibernate: select employeede0_.employee_id as employee1_1_0_, employeede0_.street as street1_0_, employeede0_.city as city1_0_, employeede0_.state as state1_0_, employeede0_.country as country1_0_ from employeedetail employeede0_ where employeede0_.employee_id=? 
Exception in thread "main" org.hibernate.id.IdentifierGenerationException: attempted to assign id from null one-to-one property: employee 
    at org.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:44) 
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:99) 
    at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:186) 
    at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:240) 
    at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:120) 
    at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:687) 
    at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:669) 
    at org.hibernate.engine.CascadingAction$6.cascade(CascadingAction.java:245) 
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:268) 
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:216) 
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169) 
    at org.hibernate.engine.Cascade.cascade(Cascade.java:130) 
    at org.hibernate.event.def.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:456) 
    at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:194) 
    at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:240) 
    at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:120) 
    at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53) 
    at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677) 
    at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661) 
    at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665) 
    at CustomerClient.main(CustomerClient.java:31) 

Answer 1

Bạn nói với Hibernate để tạo ra EmployeeDetail ID từ ID của tài sản employee của nó, nhưng bạn không bao giờ khởi khách sạn này.

Thêm edetail.setEmployee(employee); vào mã của bạn.