fetch list based on id present in another entity - spring-boot

Question

this is my order entity,
#Data
#NoArgsConstructor
#AllArgsConstructor
#ToString
#Entity
#Table(name = "ordertab")
public class Order {
#Id
private int orderId;
private String orderDate;
#ManyToMany(targetEntity = Medicine.class,cascade = CascadeType.ALL)
#JoinTable(name="ord_med",
joinColumns = {#JoinColumn(name="ord_id")},
inverseJoinColumns = {#JoinColumn(name="med_id")})
private List<Medicine> medicineList;
private String dispatchDate;
private float totalCost;
#ManyToOne(targetEntity = Customer.class,cascade = CascadeType.ALL)
#JoinColumn(name= "custord_fk",referencedColumnName = "customerId")
private Customer customer;
private String status;
}
and this is my medicine entity,
#Data
#NoArgsConstructor
#AllArgsConstructor
#ToString
#Entity
public class Medicine {
#Id
private String medicineId;
private String medicineName;
private float medicineCost;
private LocalDate mfd;
private LocalDate expiryDate;
**#ManyToMany(cascade = CascadeType.ALL, mappedBy = "medicineList")
private List<Order> orderList;** //order/ medicine many to many mapping
// OneToOne Mapping
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "categoryId", referencedColumnName = "categoryId")
private Category category;
in my order service interface i have a method,
List showAllOrder(string medId);
I have to fetch all orders that has the matching med id.
this many to many mapping have created a additional table ord_med with two columns named ord_id,med_id(type foreign keys).In addition to that due to this bidirectional mapping(i believe it is) while creating object of medicine entity its asking me to add orderlist ,how to approach this method or how exactly should i solve this. thankyou.

Answer 1

in your OrderRepository you can implements this method
findByMedicineId(String id);

Answer 2

if i go for findByMedicineId(String id);
it gives error saying no property medicineId is found in Order entity,cuz the property medicineId is in Medicine entity,while defining custom method in repository follows rules, refer https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods.query-creation
anyway I have found the solution for this,
public List<Order> getOrderListBasedOnMedicineId(String medicineid) {
Optional<Medicine> med=medicineRepo.findById(medicineid);//find if medicine is present in database with the id.
if(med.isEmpty()) {
return null;
}
List<Order> orders = medicineServ.getOrderList(); //getorderlist defined in service implementation of medicine.
List<Order> ordersWithMedId = new ArrayList();//new list to add all orders that has atleast one medicineId that matches.
for(int i=0;i<orders.size();i++) {
List<Medicine> medicines= orders.get(i).getMedicineList();
for(int j=0;j<medicines.size();j++) {
ordersWithMedId.add(orders.get(i));
}
}
return ordersWithMedId;//returning the list of orders.
}
#Override
public List<Order> getOrderList() {//medicine service implementation
return orderRepo.findAll();
}
//OrderController
#GetMapping("/orders/list/{id}")
public ResponseEntity<List<Order>> getOrderListBasedOnMedicineId(#PathVariable("id") String id) {
List<Order> ord= orderService.getOrderListBasedOnMedicineId(id);
if(ord==null) {
throw new OrderNotFoundException("Order not found with medicine id:"+id);
}
return new ResponseEntity<List<Order>>(orderService.getOrderListBasedOnMedicineId(id),HttpStatus.OK);
}