org.hibernate.PersistentObjectException：传递给持久化的分离实体：多对一单向答案

【问题标题】：org.hibernate.PersistentObjectException: detached entity passed to persist: Many to one unidirectionalorg.hibernate.PersistentObjectException：传递给持久化的分离实体：多对一单向
【发布时间】：2023-03-29 06:47:01
【问题描述】：

我正在尝试在 Spring Boot 中使用休眠模式进行多对一单向映射。我有以下学生班-很多

package jpa.many.to.one.unidirectional.model;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
 
@Entity
@Table(name = "STUDENT")
public class Student {
 
    @Id
    @GeneratedValue
    @Column(name = "STUDENT_ID")
    private long id;
 
    @Column(name = "FIRST_NAME")
    private String firstName;
 
    @Column(name = "LAST_NAME")
    private String lastName;
 
    @Column(name = "SECTION")
    private String section;
 
    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name="UNIVERSITY_ID")
    private University university;
 
 
    public Student() {
    }
 
    public Student(String firstName, String lastName, String section, University university) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.section = section;
        this.university = university;
    }
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getFirstName() {
        return firstName;
    }
 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    public String getLastName() {
        return lastName;
    }
 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    public String getSection() {
        return section;
    }
 
    public void setSection(String section) {
        this.section = section;
    }
 
    public University getUniversity() {
        return university;
    }
 
    public void setUniversity(University university) {
        this.university = university;
    }
 
    @Override
    public String toString() {
        return "Student [id=" + id + ", firstName=" + firstName + ", lastName="
                + lastName + ", section=" + section + "]";
    }
 
}

大学 - 一节课

package jpa.many.to.one.unidirectional.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
 
@Entity
@Table(name = "UNIVERSITY")
public class University {
 
    @Id
    @GeneratedValue
    @Column(name = "UNIVERSITY_ID")
    private long id;
 
    @Column(name = "NAME")
    private String name;
 
    @Column(name = "COUNTRY")
    private String country;
 
    public University() {
 
    }
 
    public University(String name, String country) {
        this.name = name;
        this.country = country;
    }
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getCountry() {
        return country;
    }
 
    public void setCountry(String country) {
        this.country = country;
    }
 
    @Override
    public String toString() {
        return "University [id=" + id + ", name=" + name + ", country=" + country + "]";
    }
 
}

应用程序保存并运行为

package jpa.many.to.one.unidirectional;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

import jpa.many.to.one.unidirectional.model.Student;
import jpa.many.to.one.unidirectional.model.University;
import jpa.many.to.one.unidirectional.repo.StudentRepo;
import jpa.many.to.one.unidirectional.repo.UniversityRepo;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
//      SpringApplication.run(Application.class, args);

        ConfigurableApplicationContext configurableApplicationContext = SpringApplication.run(Application.class, args);
        UniversityRepo universityRepo = configurableApplicationContext.getBean(UniversityRepo.class);
        StudentRepo studentRepo = configurableApplicationContext.getBean(StudentRepo.class);

        University university = new University("MG", "India");
        
        Student fstudent = new Student("Deeksha", "Sivakumar", "A", university);
        fstudent.setUniversity(university);
        studentRepo.save(fstudent);
        
        
        Student fstudent1 = new Student("Sivakumar", "Nair", "A", university);
        fstudent1.setUniversity(university);
        studentRepo.save(fstudent1);

    }

}

但我明白了引起：org.hibernate.PersistentObjectException：分离的实体传递给坚持：jpa.many.to.one.unidirectional.model.University 在 org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:120) 在 org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:113) 在 org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) 在 org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) 在 org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) 在 org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:492) 在 org.hibernate.engine.internal.Cascade.cascadeAssociation（Cascade.java:416）在 org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:218) 在 org.hibernate.engine.internal.Cascade.cascade(Cascade.java:151) 在 org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) 在 org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) 在 org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) 在 org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) 在 org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient（DefaultPersistEventListener.java:185）在 org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) 在 org.hibernate.event.internal.DefaultPersistEventListener.onPersist（DefaultPersistEventListener.java:55）在 org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) 在 org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:720) 在 org.hibernate.internal.SessionImpl.persist(SessionImpl.java:706) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/java.lang.reflect.Method.invoke(Method.java:567) 在 org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:314) 在 com.sun.proxy.$Proxy55.persist（未知来源）在 org.springframework.data.jpa.repository.support.SimpleJpaRepository.save（SimpleJpaRepository.java:554）在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/java.lang.reflect.Method.invoke(Method.java:567) 在 org.springframework.data.repository.core.support.ImplementationInvocationMetadata.invoke（ImplementationInvocationMetadata.java:72）在 org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:382) 在 org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:205) 在 org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:550) 在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) 在 org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:155) 在 org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130) 在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) 在 org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) 在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) 在 org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) 在 org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) 在 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) 在 org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ... 13 更多

我在多对一注释中尝试了 cascade.merge 和 optional-=false。但我收到上述错误请帮忙

【问题讨论】：

标签： java spring spring-boot hibernate jpa

【解决方案1】：

@ManyToOne(cascade = CascadeType.ALL) 在您的情况下，这似乎是一个坏主意，因为删除学生会导致删除相关的大学。由于大学可以有多个学生，其他学生将成为孤儿

我认为你应该在 University Entity 中使用这种关系，而不是 Student Entity

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name="STUDENT_ID")
private List<Student> students;

如果您想使用您的模型，请在将其设置为学生之前尝试保存大学（因为在您的代码中，您尝试保存相同的大学两次，第一次使用 fstudent，第二次使用 fstudent1），在这种情况下我建议你不要使用级联：

  University university = universityRepo.save(new University("MG", "India"));
    
    Student fstudent = new Student("Deeksha", "Sivakumar", "A", university);
    fstudent.setUniversity(university);
    studentRepo.save(fstudent);
    
    
    Student fstudent1 = new Student("Sivakumar", "Nair", "A", university);
    fstudent1.setUniversity(university);
    studentRepo.save(fstudent1);

【讨论】：

早安阿扎比！！！感谢您的回复。在设置学生价值观和大学价值观之前，我为大学明确保存。还删除了所有级联，并在学生班的大学参考中给出了@ManyToOne(optional = false) ...我的要求是学生实体应该为每个学生提供大学参考
现在我得到了预期的结果
我还有一个问题...保持相同的关系..如何插入具有相同大学 ID 的新孩子
我也没有找到接受的选项...请告诉我在哪里可以做到这一点
对于你的问题，需要设置save返回的大学，或者通过id搜索并设置在Student中