如何使用hibernate将三个表映射在一起答案

【问题标题】：How to use hibernate to map three table together如何使用hibernate将三个表映射在一起
【发布时间】：2021-05-04 23:36:29
【问题描述】：

下面是我的三张桌子。我在使用@OneToMany 将这三个表映射在一起时遇到问题。不确定设置这三个实体的正确方法。谢谢

有很多问题的主题

具有多种答案选项的问题

CREATE TABLE `topic` (
  `topic_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(100) default null,
  PRIMARY KEY (`topic_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

CREATE TABLE `question` (
  `question_id` int unsigned NOT NULL AUTO_INCREMENT,
  `topic_id` int unsigned NOT NULL,
  `question` varchar(100) NOT NULL,
  `answer` varchar(100) NOT NULL,
  PRIMARY KEY (`question_id`),
  KEY `topic_id` (`topic_id`),
  CONSTRAINT `items_ibfk_1` FOREIGN KEY (`topic_id`) REFERENCES `topic` (`topic_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

CREATE TABLE `option` (
  `option_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `question_id` int(11) unsigned NOT NULL,
  `option` varchar(100) not null,
  PRIMARY KEY (`option_id`),
  KEY `question_id` (`question_id`),
  CONSTRAINT `items_ibfk_2` FOREIGN KEY (`question_id`) REFERENCES `question` (`question_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

【问题讨论】：

标签： java sql hibernate

【解决方案1】：

Below is the code snippet:
@Entity
class Topic
{
 //other fields
 @OneToMany(mappedBy="topic")
private List<Question> question;

}
@Entity
class Question
{
//other fields
@ManyToOne
@JoinColumn(name="topic_id")
private Topic topic;

@OneToMany(mappedBy="question")
private Option option;
}
@Entity    
class Option
{
//other fields
@ManyToOne
@JoinColumn(name="question_id")
private Question question;
}

【讨论】：

感谢您的设置，但我收到一些关于：'entityManagerFactory' 的错误消息。
在 pom.xml 我更新了版本，但仍然给我同样的错误。

【解决方案2】：

下面是我如何设置这三个实体。但应用程序运行失败：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.generator.ExamMaker.entity.Question.options

主题实体

@Entity
@Table(name="topic")
public class Topic {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="topic_id")
    private int id;
    
    @Column(name="name")
    private String name;
    
    @OneToMany(mappedBy="topic")
    private List<Question> questions;
    
    // Define Constructors
    public Topic() {
    }

    public Topic(String name) {
        this.name = name;
    }

    // Define Getter/Setter
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Question> getQuestions() {
        return questions;
    }

    public void setQuestions(List<Question> questions) {
        this.questions = questions;
    }   

}

问题实体

@Entity
@Table(name="question")
public class Question {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="question_id")
    private int id;
    
    @Column(name="question")
    private String question;
    
    @Column(name="answer")
    private String answer;
    
    @Column(name="topic_id")
    private int topic_id;
    
    @ManyToOne
    @JoinColumn(name="topic_id")
    private Topic topic;

    @OneToMany(mappedBy="question")
    private Option options;
    
    // Define Constructors
    public Question() {}

    public Question(String question, String answer, int topic_id) {
        this.question = question;
        this.answer = answer;
        this.topic_id = topic_id;
    }

    // Define Getter/Setter
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getQuestion() {
        return question;
    }

    public void setQuestion(String question) {
        this.question = question;
    }

    public String getAnswer() {
        return answer;
    }

    public void setAnswer(String answer) {
        this.answer = answer;
    }

    public int getTopic_id() {
        return topic_id;
    }

    public void setTopic_id(int topic_id) {
        this.topic_id = topic_id;
    }

    public Topic getTopic() {
        return topic;
    }

    public void setTopic(Topic topic) {
        this.topic = topic;
    }

    public Option getOptions() {
        return options;
    }

    public void setOptions(Option options) {
        this.options = options;
    }
}

选项实体

@Entity
@Table(name="option")
public class Option {
    
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="option_id")
    private int id;
    
    @Column(name="option")
    private String option;
    
    @Column(name="question_id")
    private int question_id;
    
    @ManyToOne
    @JoinColumn(name="question_id")
    private Question question;
    
    // Define Constructors
    public Option() {}

    public Option(String option, int question_id) {
        this.option = option;
        this.question_id = question_id;
    }

    // Define Getter/Setter
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getOption() {
        return option;
    }

    public void setOption(String option) {
        this.option = option;
    }

    public int getQuestion_id() {
        return question_id;
    }

    public void setQuestion_id(int question_id) {
        this.question_id = question_id;
    }
}

【讨论】：

使用更新后的hibernate jar兼容库

【解决方案3】：

在 pom.xml 中我更新了版本，但仍然给我同样的错误。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.generator</groupId>
    <artifactId>ExamMaker</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>ExamMaker-Backend</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <maven-jar-plugin.version>3.1.1</maven-jar-plugin.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

错误信息

2021-05-06 19:51:40.142  INFO 2161 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2021-05-06 19:51:40.146  INFO 2161 --- [  restartedMain] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-05-06 19:51:40.148 ERROR 2161 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Repeated column in mapping for entity: com.generator.ExamMaker.entity.Question column: topic_id (should be mapped with insert="false" update="false")
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1786) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:602) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1154) ~[spring-context-5.3.5.jar:5.3.5]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:908) ~[spring-context-5.3.5.jar:5.3.5]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.5.jar:5.3.5]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:769) [spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:761) [spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) [spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) [spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1313) [spring-boot-2.4.4.jar:2.4.4]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1302) [spring-boot-2.4.4.jar:2.4.4]
    at com.generator.ExamMaker.ExamMakerBackendApplication.main(ExamMakerBackendApplication.java:10) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.4.4.jar:2.4.4]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Repeated column in mapping for entity: com.generator.ExamMaker.entity.Question column: topic_id (should be mapped with insert="false" update="false")
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:421) ~[spring-orm-5.3.5.jar:5.3.5]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) ~[spring-orm-5.3.5.jar:5.3.5]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1845) ~[spring-beans-5.3.5.jar:5.3.5]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1782) ~[spring-beans-5.3.5.jar:5.3.5]
    ... 22 common frames omitted
Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.generator.ExamMaker.entity.Question column: topic_id (should be mapped with insert="false" update="false")
    at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:862) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.mapping.PersistentClass.checkPropertyColumnDuplication(PersistentClass.java:880) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:902) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:634) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.mapping.RootClass.validate(RootClass.java:267) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:354) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:298) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:468) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1259) ~[hibernate-core-5.4.29.Final.jar:5.4.29.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) ~[spring-orm-5.3.5.jar:5.3.5]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.3.5.jar:5.3.5]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) ~[spring-orm-5.3.5.jar:5.3.5]
    ... 26 common frames omitted

【讨论】：