springJPA - How to read from a joined table?

Question

I'm trying to work in spring-boot with a table that have a composite-key.
(Integer & Integer in my case)

I used this answer to understand how to write to table with a composite key:

https://stackoverflow.com/a/3588400/7658754

but I can't understand how to read from it.

as the function "findOne()" of CrudRepository can get only one parameter (Integer in my case) but then the EntityManager throws an Exception because it expects to get an "Composite-Key-Bean" (like "TimePK" in the above answer) and not an Integer.

My Entities as requested:

CustomersCouponsPK.class :

package beans;

import java.io.Serializable;

import javax.persistence.Embeddable;

@Embeddable
public class CustomersCuoponsPK implements Serializable {

 private Integer cust_id;
 private Integer coupon_id;

 public CustomersCuoponsPK() {
 }
 
 public CustomersCuoponsPK(int cust_id, int coupon_id) {
  super();
  this.cust_id = cust_id;
  this.coupon_id = coupon_id;
 }

 public int getCust_id() {
  return cust_id;
 }

 public void setCust_id(int cust_id) {
  this.cust_id = cust_id;
 }

 public int getCoupon_id() {
  return coupon_id;
 }

 public void setCoupon_id(int coupon_id) {
  this.coupon_id = coupon_id;
 }

 @Override
 public int hashCode() {
  final int prime = 31;
  int result = 1;
  result = prime * result + ((coupon_id == null) ? 0 : coupon_id.hashCode());
  result = prime * result + ((cust_id == null) ? 0 : cust_id.hashCode());
  return result;
 }

 @Override
 public boolean equals(Object obj) {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  if (getClass() != obj.getClass())
   return false;
  CustomersCuoponsPK other = (CustomersCuoponsPK) obj;
  if (coupon_id == null) {
   if (other.coupon_id != null)
    return false;
  } else if (!coupon_id.equals(other.coupon_id))
   return false;
  if (cust_id == null) {
   if (other.cust_id != null)
    return false;
  } else if (!cust_id.equals(other.cust_id))
   return false;
  return true;
 }

}

CustomersCoupons.class:

package beans;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;

@Entity
public class CustomersCoupons {

 @EmbeddedId
 private CustomersCuoponsPK customersCuoponsPK;

 public CustomersCoupons() {

 }

 public CustomersCoupons(CustomersCuoponsPK customersCuoponsPK) {
  super();
  this.customersCuoponsPK = customersCuoponsPK;
 }

 public CustomersCuoponsPK getCustomersCuoponsPK() {
  return customersCuoponsPK;
 }

 public void setCustomersCuoponsPK(CustomersCuoponsPK customersCuoponsPK) {
  this.customersCuoponsPK = customersCuoponsPK;
 }

}

CustomersCouponsRepo:

package repos;

import org.springframework.data.jpa.repository.JpaRepository;

import beans.CustomersCoupons;
import beans.CustomersCuoponsPK;

public interface CustomersCouponsRepo extends JpaRepository<CustomersCoupons, Integer> {

 public default CustomersCoupons findOne(int cust_id, int coupon_id){
  if(this.getOne(cust_id).equals(this.getOne(coupon_id))){
   CustomersCuoponsPK pk = new CustomersCuoponsPK();
   pk.setCoupon_id(coupon_id);
   pk.setCust_id(cust_id);
   CustomersCoupons cc = new CustomersCoupons();
   cc.setCustomersCuoponsPK(pk);
   return cc;
  }
  return null;
 }

}

CustomerCouponsDAO:

package DAOs;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import beans.CustomersCoupons;
import beans.CustomersCuoponsPK;
import repos.CustomersCouponsRepo;

@Repository
public class CustomersCouponsDAO {

 @Autowired
 private CustomersCouponsRepo repo;

 public void createCustomerCoupon(int cust_id, int coupon_id) {
  CustomersCoupons customersCoupons = new CustomersCoupons(new CustomersCuoponsPK(cust_id, coupon_id));
  repo.save(customersCoupons);
 }

 public List<CustomersCoupons> getAllCustomersCoupons() {
  return (List<CustomersCoupons>) repo.findAll();
 }

 public CustomersCoupons readCustomersCoupons(int cust_id, int coupon_id) {
  return repo.findOne(cust_id, coupon_id);
 }

 public void updateCustomersCoupons(CustomersCoupons customersCoupons) {
  repo.save(customersCoupons);
 }

 public void deleteC(int cust_id, int coupon_id) {
 }
}

the Exception:

Exception in thread "main" org.springframework.dao.InvalidDataAccessApiUsageException: Provided id of the wrong type for class beans.CustomersCoupons. Expected: class beans.CustomersCuoponsPK, got class java.lang.Integer; nested exception is java.lang.IllegalArgumentException: Provided id of the wrong type for class beans.CustomersCoupons. Expected: class beans.CustomersCuoponsPK, got class java.lang.Integer
 at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:384)
 at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:246)
 at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:488)
 at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
 at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
 at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
 at com.sun.proxy.$Proxy76.getOne(Unknown Source)
 at repos.CustomersCouponsRepo.findOne(CustomersCouponsRepo.java:11)
 at java.lang.invoke.MethodHandle.invokeWithArguments(Unknown Source)
 at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:62)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
 at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
 at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
 at com.sun.proxy.$Proxy76.findOne(Unknown Source)
 at DAOs.CustomersCouponsDAO.readCustomersCoupons(CustomersCouponsDAO.java:28)
 at DAOs.CustomersCouponsDAO$$FastClassBySpringCGLIB$$d50d5f2d.invoke(<generated>)
 at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
 at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
 at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)
 at DAOs.CustomersCouponsDAO$$EnhancerBySpringCGLIB$$1907e960.readCustomersCoupons(<generated>)
 at com.example.CouponSystem.CouponSystemApplication.main(CouponSystemApplication.java:35)
Caused by: java.lang.IllegalArgumentException: Provided id of the wrong type for class beans.CustomersCoupons. Expected: class beans.CustomersCuoponsPK, got class java.lang.Integer
 at org.hibernate.jpa.spi.AbstractEntityManagerImpl.getReference(AbstractEntityManagerImpl.java:1019)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:298)
 at com.sun.proxy.$Proxy69.getReference(Unknown Source)
 at org.springframework.data.jpa.repository.support.SimpleJpaRepository.getOne(SimpleJpaRepository.java:278)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:504)
 at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:489)
 at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:56)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
 at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
 at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
 at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
 at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
 ... 37 more
Caused by: org.hibernate.TypeMismatchException: Provided id of the wrong type for class beans.CustomersCoupons. Expected: class beans.CustomersCuoponsPK, got class java.lang.Integer
 at org.hibernate.event.internal.DefaultLoadEventListener.checkIdClass(DefaultLoadEventListener.java:166)
 at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:86)
 at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1129)
 at org.hibernate.internal.SessionImpl.access$2600(SessionImpl.java:164)
 at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.getReference(SessionImpl.java:2669)
 at org.hibernate.internal.SessionImpl.load(SessionImpl.java:965)
 at org.hibernate.jpa.spi.AbstractEntityManagerImpl.getReference(AbstractEntityManagerImpl.java:1013)
 ... 59 more

Answer 1

The ID of your entity is of type CustomerCuoponsPK. So your repo should implement JpaRepository, not JpaRepository. That's exactly what the error message of the exception tells you. Change the implementation based on below.

package repos;

import org.springframework.data.jpa.repository.JpaRepository;

import beans.CustomersCoupons;
import beans.CustomersCuoponsPK;

public interface CustomersCouponsRepo extends JpaRepository<CustomersCoupons, CustomersCuoponsPK> {

 public default CustomersCoupons findOne(CustomersCuoponsPK pk){
  return findOne(pk);
 }