How to write query for many to one mapped entity in JpaRepository - spring

Question

I have two entities and mapped those using many-to-one annotation but after writing a query for find object using another table id I got an error when I commented out that line and method called to that application work but I want to implement that functionality and please help me
These are my entity classes:
#Entity
#Table(name = "Contract")
public class Contract implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "contractId")
private long contractId;
#Column(name="start_date")
private Date st_date;
#Column(name="end_date")
private Date end_date;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "hotel_id", nullable = false)
#OnDelete(action = OnDeleteAction.CASCADE)
#JsonIgnore
private Hotel hotel;
// getters and setters
Second entity
#Entity
#Table(name="Hotel")
public class Hotel {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="hotel_id")
private long hotel_id;
#Column(name="hotel_name")
private String hotel_name;
#Column(name="hotel_location")
private String hotel_location;
#Column(name="hotel_email")
private String hotel_email;
#Column(name="hotel_telephone")
private String hotel_telephone
// getters and setters
My contract service class
#Service
public class ContractService {
#Autowired
private ContractRepository contractRepository;
#Autowired
private HotelRepository hotelRepository;
public List<Contract> getAllContracts(){
return contractRepository.findAll();
}
public List<Contract> findByHotelId(Long hotelId,Pageable pageable){
return contractRepository.findByHotelId(hotelId, pageable);
}
public ResponseEntity<?> deleteContract(Long hotelId, Long contractId)
{
return contractRepository.findByIdAndHotelId(contractId,
hotelId).map(Contract -> {
contractRepository.delete(Contract);
return ResponseEntity.ok().build();
}).orElseThrow(() -> new ResourceNotFoundException("Comment not found
with ContractId " + contractId + " and hotelId " + hotelId));
}
My contract repository
#Repository
public interface ContractRepository extends JpaRepository<Contract, Long> {
List<Contract> findByHotelId(Long hotelId, Pageable pageable);
Optional<Contract> findByIdAndHotelId(Long id, Long hotelId);
}
I got this error when running my project
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'contractController': Unsatisfied dependency expressed through field 'contractService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'contractService': Unsatisfied dependency expressed through field 'contractRepository'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contractRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.sunTravel.sunRest.repository.ContractRepository.findByHotelId(java.lang.Long,org.springframework.data.domain.Pageable)! No property id found for type Hotel! Traversed path: Contract.hotel.

Answer 1

First Solution: based on your stack trace, Spring data is looking for id variable (primary key) in your Hotel class. So please change private long hotel_id; to private long id;
Another solution (no need to change anything just add your own query):
write your own JPA query using #Query.
Example:
#Query("SELECT contract from Contract as contract where contract.hotel.hotel_id = :hotelId")
List<Contract> findByHotelId(Long hotelId, Pageable pageable);

Answer 2

You should rename your Primary Key from hotel_id to id then only your repository method will work.
#Entity
#Table(name="Hotel")
public class Hotel {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="hotel_id")
private long id;
#Column(name="hotel_name")
private String hotel_name;
#Column(name="hotel_location")
private String hotel_location;
#Column(name="hotel_email")
private String hotel_email;
#Column(name="hotel_telephone")
private String hotel_telephone
// getters and setters