I am encountering a problem in my Spring Boot JPA application related to relationships between the Owner and Car entities. The issue arises when attempting to associate a new Car with an existing Owner or when adding a new Owner with a set of Cars. While the owner and cars are added successfully to the database, the owner_id in the Car table is set to null and when trying to retrieve an owner I get no response.
Could anyone help to find a solution : My objective is adding owner with sets of cars, retrieving owners with their cars and while inserting a car with an existing owner it will be retrieved also.
these are my classes and json payloads:
Car.java class
@Entity@Table(name="Car")@Datapublic class Car { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "car_id") private Long id; @Column(name = "name") private String car_name; @Column(name = "model") private String Lmodel; @Column(name = "firstY") private String firsty; @ManyToOne() @JoinColumn(name="owner_id", referencedColumnName = "owner_id") private Owner owner;Owner.java Class
@Entity@Table(name="Owner")@Datapublic class Owner { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "owner_id", nullable = false) private Long id; @Column(name = "first_name") private String first_name; @Column(name = "last_name") private String last_name; @Column(name = "address") private String address; @OneToMany(targetEntity = Car.class, mappedBy = "owner", cascade = CascadeType.ALL, orphanRemoval = true) private List<Car> car;}Main Controller
package com.example.product.controllers;import com.example.product.model.Car;import com.example.product.model.CarService;import com.example.product.model.Owner;import com.example.product.model.OwnerService;import jakarta.transaction.Transactional;import lombok.AllArgsConstructor;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.HttpStatus;import org.springframework.web.bind.annotation.*;import java.util.List;@AllArgsConstructor@RestControllerpublic class MainController { @Autowired private CarService carService; @Autowired private OwnerService ownerService; @Transactional @DeleteMapping(value = "/Owner/{id}") public void deleteOwner(@PathVariable Long id){ ownerService.deleteOwnerById(id); } @PostMapping(value = "/Owner") public void addOwner(@RequestBody Owner owner){ ownerService.addOwner(owner); } @GetMapping(value = "/Owner/{id}") public Owner getOwner(@PathVariable Long id){ return ownerService.findOwnerById(id); } @PutMapping(value = "/Owner") public void updateOwner(Long id, String firstName, String lastName, String email, Car car){ ownerService.updateOwner(id,firstName,lastName,email,car); } @GetMapping(value = "/Owners") public List<Owner> getAllOwners(){ return ownerService.getAllOwners();} @Transactional @DeleteMapping (value = "/Car/{id}") public void deleteCar(@PathVariable Long id){ carService.deleteCarById(id); } @PostMapping(value = "/Car") @ResponseStatus(HttpStatus.CREATED) public void addCar(@RequestBody Car car){ carService.addCar(car); } @GetMapping(value = "/Car/{id}") public Car getCar(@PathVariable Long id){ return carService.getCarById(id); } @PutMapping(value = "/Car") public void updateCar (Long id,String firsty,String name,String model){ carService.updateCarById(firsty,name,model,id); } @GetMapping(value="/Cars") public List<Car> getAllCars(){ return carService.getAllCars(); }}Json payload to add a car into the database
{"car_name": "Toyota","lmodel": "Camry","firsty": "2023","owner": {"id": 1 }}Json payload to add an owner into the database
{"first_name": "John","last_name": "Doe","address": "123 Main Street","car": [ {"car_name": "BMW","lmodel": "Model 3","firsty": "2022" }, {"car_name": "Mercedes","lmodel": "C-Class","firsty": "2021" } ]}