Hibernate, Spring framework and many-to-many

Could you please help me with a simple example of many-to-many relationship using Spring (framework NOT BOOT OR MVC) and Hibernate. I have two classes Users and Courses and I need an intermediate table(class) UserCourse. I can't use @ManyToMany annotations because I need to add extra columns to my intermediate table so I need to do something like in this example: https://examples.javacodegeeks.com/enterprise-java/hibernate/hibernate-many-to-many-relationship-with-join-table-example/ Could you please explain me how to include spring into this. I tried something but I received this error:

WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cursDAOImpl': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [spring.xml]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.proiect.persistence.entity.UserCurs.pk.curs in com.proiect.persistence.entity.Curs.usercurs Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cursDAOImpl': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [spring.xml]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.proiect.persistence.entity.UserCurs.pk.curs in com.proiect.persistence.entity.Curs.usercurs at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:586) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:364) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1269) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:551) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:481) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83) at Application.main(Application.java:23) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [spring.xml]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.proiect.persistence.entity.UserCurs.pk.curs in com.proiect.persistence.entity.Curs.usercurs at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1631) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:481) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1136) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1064) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:583) ... 15 more Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: com.proiect.persistence.entity.UserCurs.pk.curs in com.proiect.persistence.entity.Curs.usercurs at org.hibernate.cfg.annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:768) at org.hibernate.cfg.annotations.CollectionBinder$1.secondPass(CollectionBinder.java:728) at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:70) at org.hibernate.cfg.Configuration.originalSecondPassCompile(Configuration.java:1695) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1424) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1844) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1928) at org.springframework.orm.hibernate4.LocalSessionFactoryBuilder.buildSessionFactory(LocalSessionFactoryBuilder.java:372) at org.springframework.orm.hibernate4.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:454) at org.springframework.orm.hibernate4.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:439) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1689) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1627) ... 25 more

@Entity
@Table(name="user")
public class User implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer user_id;

    @Column(name="username")
    private String username;

    @Column(name="firstname")
    private String firstname;

    @Column(name="lastname")
    private String lastname;

    @Column(name="password")
    private String password;

    @Column(name="email")
    private String email;


    @OneToMany(fetch = FetchType.LAZY,mappedBy = "pk.user",cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.PERSIST})
    private Set<UserCurs> usercurs = new HashSet<UserCurs>(); 

    public Integer getUser_id() {
        return user_id;
    }

    public void setUser_id(Integer user_id) {
        this.user_id = user_id;
    }

    public String getUsername() {
        return username;
    }


    public void setUsername(String username) {
        this.username = username;
    }


    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 getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }


    public Set<UserCurs> getUsercurs() {
        return usercurs;
    }

    public void setUsercurs(Set<UserCurs> usercurs) {
        this.usercurs = usercurs;
    }

and here is my Course entity

        package com.proiect.persistence.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;


@Entity
@Table(name = "curs")
public class Curs implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer curs_id;

    @Column(name = "denumire")
    private String denumire;


    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.curs")
    private Set<UserCurs> usercurs = new HashSet<UserCurs>();

    public Curs() {
    }

    public Curs(String denumire) {
        this.denumire = denumire;
    }



    public Integer getCurs_id() {
        return curs_id;
    }

    public void setCurs_id(Integer curs_id) {
        this.curs_id = curs_id;
    }

    public String getDenumire() {
        return denumire;
    }

    public void setDenumire(String denumire) {
        this.denumire = denumire;
    }

    public Set<UserCurs> getUsercurs() {
        return usercurs;
    }


    public void setUsercurs(Set<UserCurs> usercurs) {
        this.usercurs = usercurs;
    }

    @Override
    public String toString() {
        return "Curs [curs_id=" + curs_id + ", denumire=" + denumire + ", usercurs=" + usercurs + "]";
    }


}

And there I tried to connect these classes through UserCurs

package com.proiect.persistence.entity;

import java.beans.Transient;

import javax.persistence.AssociationOverride;
import javax.persistence.AssociationOverrides;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.Table;

@Entity
@Table(name="user_curs")
@AssociationOverrides({
    @AssociationOverride(name="pk.user", joinColumns = @JoinColumn(name="user_id")),
    @AssociationOverride(name="pk.curs", joinColumns = @JoinColumn(name="curs_id"))
})
public class UserCurs implements java.io.Serializable {

    private static final long serialVersionUID = 4050660680047579957L;

    private UserCursID pk = new UserCursID();

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

    @Transient
    public User getUser() {
        return getPk().getUser();
    }

    public void setUser(User user) {
        getPk().setUser(user);
    }

    @Transient
    public Curs getCs() {
        return getPk().getCs();
    }

    public void setCs(Curs c) {
        getPk().setCs(c);
    }

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

}

UserCursID:

package com.proiect.persistence.entity;

import javax.persistence.Embeddable;
import javax.persistence.ManyToOne;

@Embeddable
public class UserCursID implements java.io.Serializable {

    private static final long serialVersionUID = -9120607274421816301L;

    @ManyToOne
    private User user;
    @ManyToOne
    private Curs cs;

    public User getUser() {
        return user;
    }
    public void setUser(User user) {
        this.user = user;
    }
    public Curs getCs() {
        return cs;
    }
    public void setCs(Curs cs) {
        this.cs = cs;
    }   

}

And this is my spring.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.3.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-4.3.xsd ">


    <context:property-placeholder
        location="classpath:database.properties" />

    <context:component-scan
        base-package="com.proiect.persistence.dao"></context:component-scan>
    <tx:annotation-driven />


    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName"
            value="${jdbc.driverClassName}" />
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
    </bean>


    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan">
            <list>
                <value>com.proiect.persistence.entity</value>
            </list>
        </property>

        <property name="annotatedClasses">
            <list>

            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
                <prop key="hibernate.show_sql">${hibernate.show_sql:true}</prop>
                <prop key="hibernate.format_sql">${hibernate.format_sql:false}</prop>
                <prop key="hibernate.hbm2ddl.auto">create</prop>

            </props>
        </property>
    </bean>



    <bean id="transactionManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

    <tx:annotation-driven />

    <bean id="persistenceExceptionTranslationPostProcessor"
        class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

</beans>

Solution

First suggestion is an incorrect mapping between name properties, i.e.

@AssociationOverrides({
    @AssociationOverride(name="pk.user", joinColumns = @JoinColumn(name="user_id")),
    @AssociationOverride(name="pk.curs", joinColumns = @JoinColumn(name="curs_id"))
})

You override relationship for pk.curs, that must correspond to name of field curs of UserCursID class. But you have

@ManyToOne
    private Curs cs;

Try to make them consistent.