根据另一个实体中存在的 id 获取列表

Question

这是我的订单实体，

@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;

在我的订单服务接口中，我有一个方法， List showAllOrder(string medId); 我必须获取所有具有匹配 med id 的订单。这个多对多映射创建了一个额外的 table ord_med，其中有两列名为 ord_id、med_id（类型外键）。除此之外，由于这种双向映射（我相信它是），在创建医学实体对象时它要求我添加订单列表，如何处理这个方法或者我应该如何解决这个问题。谢谢。

Answer 1

在您的 OrderRepository 中您可以实现这个方法

findByMedicineId(String id);

Answer 2

如果我去找 findByMedicineId(String id); 它给出错误说在 Order 实体中找不到属性 medicineId，因为属性 medicineId 在 Medicine 实体中，同时在存储库中定义自定义方法遵循规则，参考 https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods.query-creation

无论如何我已经找到了解决方案，

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();
    }

//订单控制器

@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);
}

根据另一个实体中存在的 id 获取列表

fetch list based on id present in another entity

jpql

spring-data-jpa

spring-boot