使用复合主键和注释映射ManyToMany： [英] Mapping ManyToMany with composite Primary key and Annotation:

查看：87
本文介绍了使用复合主键和注释映射ManyToMany：的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我试图使用复合主键在学生和教学课程之间创建许多复杂的关系：



我的课程： 

  @Entity 
 @Table（name =Student_mtm_cId）
 public class Student {
 
 private String id; 
私人设置< StudentTClass> teachingClasses = new HashSet< StudentTClass>（）; 
 
 @OneToMany（fetch = FetchType.LAZY，mappedBy =pk.student）
 public Set< StudentTClass> getTeachingClasses（）{
 return teachingClasses; 
} 
 public void setTeachingClasses（Set< StudentTClass> teachingClasses）{
 this.teachingClasses = teachingClasses; 
} 
 
 public void addStudentToClass（TeachingClass teachingClass）{
 StudentTClass studentTClass = new StudentTClass（）; 
 studentTClass.setStudent（this）; 
 studentTClass.setTeachingClass（teachingClass）; 
 teachingClasses.add（studentTClass）; 
} 
 
 public void setLastName（String lastName）{
 this.lastName = lastName; 
 
 $ b @Id @GeneratedValue（generator =system-uuid）
 @GenericGenerator（name =system-uuid，strategy =uuid）
 @Column（name =student_id，nullable = false）
 public String getId（）{
 return id; 
} 
 
 public void setId（String id）{
 this.id = id; 
} 
 
 //所有其​​他setter和getter和isequal / hashCode被省略。 
}

TeachingClass：
<$










$ private String id;
私人字符串名称;
私有字符串描述;
私人设置< StudentTClass> teachingClasses = new HashSet< StudentTClass>（）;

Public TeachingClass（）{}

public TeachingClass（String name，String description）{
super（）;
this.name = name;
this.description = description;
}

public void addStudentToClass（Student student）{
StudentTClass studentTClass = new StudentTClass（）;
studentTClass.setStudent（student）;
studentTClass.setTeachingClass（this）;
teachingClasses.add（studentTClass）;
}

@OneToMany（fetch = FetchType.LAZY，mappedBy =pk.teachingClass）
public Set< StudentTClass> getTeachingClasses（）{
return teachingClasses;
}

public void setTeachingClasses（Set< StudentTClass> teachingClasses）{
this.teachingClasses = teachingClasses;
}

public void setDescription（String description）{
this.description = description;

$ b @Id @GeneratedValue（generator =system-uuid）
@GenericGenerator（name =system-uuid，strategy =uuid）
@Column（name =teachingClass_id，nullable = false）
public String getId（）{
return id;
}

public void setId（String id）{
this.id = id;


$ / code $ / pre
$ b

集合对象：

  @Entity 
 @Table（name =student_TClass_MTM）
 @AssociationOverrides（{
 @AssociationOverride（name =pk .student，joinColumns = @JoinColumn（名称= student_id数据）），
 @AssociationOverride（名称= pk.teachingClass，joinColumns = @JoinColumn（名称= teachingClass_id））
}） 
 public class StudentTClass {
 
 @EmbeddedId 
 private StudentTClassPK pk = new StudentTClassPK（）; 
 
 public StudentTClassPK getPk（）{
 return pk; 
} 
 
 public void setPk（StudentTClassPK pk）{
 this.pk = pk; 
 
 $ b $ public StudentTClass（）{} 
 
 @Transient 
 public Student getStudent（）{
 return this.pk.getStudent（ ）; 
} 
 
 @Transient 
 public TeachingClass getTeachingClass（）{
 return this.pk.getTeachingClass（）; 
} 
 
 public void setStudent（Student student）{
 this.pk.setStudent（student）; 
} 
 
 public void setTeachingClass（TeachingClass teachingClass）{
 this.pk.setTeachingClass（teachingClass）; 
} 
 
}

现在主键： p> 

  @Embeddable 
 public class StudentTClassPK implements Serializable {
 
 private static final long serialVersionUID = -7261887879839337877L ; 
私立学生; 
私人TeachingClass teachingClass; 
 
 @ManyToOne 
 public Student getStudent（）{
 return student; 
} 
 public void setStudent（Student student）{
 this.student = student; 
} 
 
 @ManyToOne 
 public TeachingClass getTeachingClass（）{
 return teachingClass; 
} 
 public void setTeachingClass（TeachingClass teachingClass）{
 this.teachingClass = teachingClass; 
} 
 public StudentTClassPK（Student student，TeachingClass teachingClass）{
 this.student = student; 
 this.teachingClass = teachingClass; 
 
 public StudentTClassPK（）{} 
 
 $ b}

当我试图坚持学生时，我得到以下错误： 

 原因：org。 hibernate.MappingException：无法确定类型：com.vanilla.objects.Student，在表：student_TClass_MTM，为列：在org.hibernate.mapping.SimpleValue [org.hibernate.mapping.Column（学生）
 .getType（SimpleValue.java:306）
。在org.hibernate.tuple.PropertyFactory.buildStandardProperty（PropertyFactory.java:143）LT 
。在org.hibernate.tuple.component.ComponentMetamodel&;初始化>（ ComponentMetamodel.java:68）
 at org.hibernate.mapping.Component.buildType（Component.java:184）
 at org.hibernate.mapping.Component.getType（Component.java:177）
在org.hibernate.mapping.SimpleValue.isValid（SimpleValue.java:290）
在org.hibernate.mapping.RootClass.validate（RootClass.java:236）
在org.hibernate.cfg .Configuration.validate（C onfiguration.java:1362）美元，org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1865 B $ B）
在org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory（LocalSessionFactoryBean.java:855）在org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory（LocalSessionFactoryBean.java:774）
 
在org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet（AbstractSessionFactoryBean.java:211）
 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods（AbstractAutowireCapableBeanFactory.java:1477）
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean（AbstractAutowireCapableBeanFactory.java:1417）
 ... 51 more

我做错了什么？

解决方案

我解决了这个问题。 

  public class StudentTClass {
 
 // @ EmbeddedId 
私人StudentTClassPK pk =新StudentTClassPK（）; 
 
 @EmbeddedId 
 public StudentTClassPK getPk（）{
 return pk; 
}


I'm trying to create manytomany realation between Student and Teaching Course using Composite Primary key:

my classes:

@Entity
@Table(name="Student_mtm_cId")
public class Student {

    private String id;
    private Set<StudentTClass> teachingClasses = new HashSet<StudentTClass>();

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.student")
    public Set<StudentTClass> getTeachingClasses() {
        return teachingClasses;
    }
    public void setTeachingClasses(Set<StudentTClass> teachingClasses) {
        this.teachingClasses = teachingClasses;
    }

    public void addStudentToClass(TeachingClass teachingClass){
        StudentTClass studentTClass = new StudentTClass();
        studentTClass.setStudent(this);
        studentTClass.setTeachingClass(teachingClass);
        teachingClasses.add(studentTClass);
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Id @GeneratedValue(generator="system-uuid")
    @GenericGenerator(name="system-uuid", strategy = "uuid")
     @Column(name = "student_id", nullable = false)
    public String getId() {
        return id;
    }

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

    //all other setters and getters and isequal/hashCode omitted.
}

TeachingClass:

@Entity
@Table(name="TechingClass_MTM")
public class TeachingClass {

    private String id;
    private String name;
    private String description;
    private Set<StudentTClass> teachingClasses = new HashSet<StudentTClass>();

    public TeachingClass(){}

    public TeachingClass(String name, String description) {
        super();
        this.name = name;
        this.description = description;
    }

    public void addStudentToClass(Student student){
        StudentTClass studentTClass = new StudentTClass();
        studentTClass.setStudent(student);
        studentTClass.setTeachingClass(this);
        teachingClasses.add(studentTClass);
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.teachingClass")
    public Set<StudentTClass> getTeachingClasses() {
        return teachingClasses;
    }

    public void setTeachingClasses(Set<StudentTClass> teachingClasses) {
        this.teachingClasses = teachingClasses;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Id @GeneratedValue(generator="system-uuid")
    @GenericGenerator(name="system-uuid", strategy = "uuid")    
     @Column(name = "teachingClass_id", nullable = false)
    public String getId() {
        return id;
    }

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

Collection Objects:

@Entity
@Table(name = "student_TClass_MTM")
@AssociationOverrides({
@AssociationOverride(name = "pk.student", joinColumns = @JoinColumn(name = "student_id")),
@AssociationOverride(name = "pk.teachingClass", joinColumns = @JoinColumn(name = "teachingClass_id"))
        })
public class StudentTClass {

    @EmbeddedId
    private StudentTClassPK pk = new StudentTClassPK();

    public StudentTClassPK getPk() {
        return pk;
    }

    public void setPk(StudentTClassPK pk) {
        this.pk = pk;
    }

    public StudentTClass() {}

    @Transient
    public Student getStudent(){
     return this.pk.getStudent();
    }

    @Transient
    public TeachingClass getTeachingClass(){
     return this.pk.getTeachingClass();     
    }

    public void setStudent(Student student){
        this.pk.setStudent(student);
    }

    public void setTeachingClass(TeachingClass teachingClass){
        this.pk.setTeachingClass(teachingClass);    
    }

    }

Now The primary Key:

@Embeddable
public class StudentTClassPK implements Serializable{

    private static final long serialVersionUID = -7261887879839337877L;
    private Student student;
    private TeachingClass teachingClass;

    @ManyToOne
    public Student getStudent() {
        return student;
    }
    public void setStudent(Student student) {
        this.student = student;
    }

    @ManyToOne
    public TeachingClass getTeachingClass() {
        return teachingClass;
    }
    public void setTeachingClass(TeachingClass teachingClass) {
        this.teachingClass = teachingClass;
    }
    public StudentTClassPK(Student student, TeachingClass teachingClass) {
        this.student = student;
        this.teachingClass = teachingClass;
    }
    public StudentTClassPK() {}


}

When I'm trying to Persist Student I got the following error:

Caused by: org.hibernate.MappingException: Could not determine type for: com.vanilla.objects.Student, at table: student_TClass_MTM, for columns: [org.hibernate.mapping.Column(student)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:306)
    at org.hibernate.tuple.PropertyFactory.buildStandardProperty(PropertyFactory.java:143)
    at org.hibernate.tuple.component.ComponentMetamodel.<init>(ComponentMetamodel.java:68)
    at org.hibernate.mapping.Component.buildType(Component.java:184)
    at org.hibernate.mapping.Component.getType(Component.java:177)
    at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:290)
    at org.hibernate.mapping.RootClass.validate(RootClass.java:236)
    at org.hibernate.cfg.Configuration.validate(Configuration.java:1362)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1865)
    at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:855)
    at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:774)
    at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
    ... 51 more

What am I doing wrong?

解决方案

I solved this issue. I mapped Getter instead of field.

public class StudentTClass {

    //@EmbeddedId
    private StudentTClassPK pk = new StudentTClassPK();

    @EmbeddedId
    public StudentTClassPK getPk() {
        return pk;
    }

这篇关于使用复合主键和注释映射ManyToMany：的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

查看全文
相关文章
Java开发最新文章
热门教程
热门工具
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆