Spring Boot JPA 无法保存对象

Question

我有一个 API 想要在修改后保存酒店对象。酒店对象的结构与另一个客户对象完全相同，但是当我尝试获取和保存酒店对象时，springboot 抛出了一个属性引用异常。我的客户对象工作得很好，所以我不确定有什么不同。我已经尝试将酒店类重命名为“Hotels”和“Hotel”，但没有成功。 这是错误：

2020-10-13 22:42:02.828 ERROR 15044 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.data.mapping.PropertyReferenceException: No property hotel found for type hotel!] with root cause

HotelDAO 对象：

package rc.springbootmongodbdemo.DAO;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import rc.springbootmongodbdemo.Entities.hotel;
import rc.springbootmongodbdemo.Entities.hsideReservation;

import java.util.Collection;
import java.util.Optional;

@Component
public class HotelDAO {
    @Autowired
    private HotelRepository repository;

    public hotel createHotel(hotel newHotel) {
        return repository.insert(newHotel);
    }

    public Collection<hsideReservation> hotelDeleteReservation(int hotel_id, hsideReservation intendedReservation){
        Optional<hotel> hotel = repository.findById(hotel_id);
        if(hotel.isPresent()){
            hotel.get().deleteReservation(intendedReservation);
            repository.save(hotel.get());
            return hotel.get().getHotelSideReservations();
        }
        else{
            System.out.println("Hotel is not registered");
            return null;
        }
    }

    public Collection<hsideReservation> newResforHotel(int hotel_id, hsideReservation newReservation){
        Optional<hotel> thisHotel = repository.findById(hotel_id);
        if(thisHotel.isPresent()){
            System.out.println(thisHotel.get().getHotelSideReservations().size());
            thisHotel.get().addReservation(newReservation);
            System.out.println(thisHotel.get().getHotelSideReservations().size());
            //This is where the issue originates
            repository.save(thisHotel.get());
            return thisHotel.get().getHotelSideReservations();
        }
        else return null;
    }

}

酒店对象

package rc.springbootmongodbdemo.Entities;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

import java.util.Collection;
import java.util.List;
public class hotel {
    @Id
    private int hotel_id;
    private String city;
    private List<hsideReservation> hotelSideReservations;

    public String getCity(){
        return city;
    }
    public int getHotel_id(){
        return hotel_id;
    }
    public Collection<hsideReservation> getHotelSideReservations(){
        return hotelSideReservations;
    }
    public Collection<hsideReservation> addReservation(hsideReservation newReservation){
        hotelSideReservations.add(newReservation);
        return hotelSideReservations;
    }


    public Collection<hsideReservation> deleteReservation(hsideReservation intendedRes) {
        for(int i = 0; i < hotelSideReservations.size(); i++){
            if(hotelSideReservations.get(i).getReservation_id() == intendedRes.getReservation_id()){
                hotelSideReservations.remove(i);
                return hotelSideReservations;
            }
        }
        return hotelSideReservations;
    }
    public String toString(){
        StringBuilder s = new StringBuilder();
        for(hsideReservation h : hotelSideReservations) {
            s.append(h.getDate());
            s.append(" , ");
        }
        return s.toString();
    }

}

客户对象：

package rc.springbootmongodbdemo.Entities;

import org.springframework.data.annotation.Id;

import java.util.Collection;
import java.util.List;

public class Customer {
    @Id
    private int id;
    private List<hotel_reservations> customerReservations;

    public Integer getId(){
        return id;
    }
    public Collection<hotel_reservations> getCustomerReservations(){
        return customerReservations;
    }

    public Collection<hotel_reservations> makeReservation(hotel_reservations reservation){
        customerReservations.add(reservation);
        return customerReservations;
    }

    public Collection<hotel_reservations> updateNewReservation(hotel_reservations editedRes){
        for(int i = 0; i < customerReservations.size(); i++){
            if(customerReservations.get(i).getReservation_id() == editedRes.getReservation_id()){
                customerReservations.get(i).set(editedRes);
                return customerReservations;
            }
        }
        return customerReservations;
        }

    public Collection<hotel_reservations> removeReservation(hotel_reservations intendedRes){
        for(int i = 0; i < customerReservations.size(); i++){
            if(customerReservations.get(i).getReservation_id() == intendedRes.getReservation_id()){
                customerReservations.remove(i);
                return customerReservations;
            }
        }
        return customerReservations;
    }

   public String toString(){
        StringBuilder s = new StringBuilder();
        for(hotel_reservations h : customerReservations) {
            s.append(h.getDate());
            s.append(" , ");
        }
        return s.toString();
   }
}

CustomerDAO 对象：

package rc.springbootmongodbdemo.DAO;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.PathVariable;
import rc.springbootmongodbdemo.Entities.Customer;
import rc.springbootmongodbdemo.Entities.hotel_reservations;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Optional;


@Component
public class CustomerDAO {
    @Autowired
    private CustomerRepository repository;
    //List of customer reservations
    public Collection<hotel_reservations> getReservations(@PathVariable("id") int id){
        Optional<Customer> customer = repository.findById(id);
        if(customer.isPresent()){
            return customer.get().getCustomerReservations();
        }
        else{
            System.out.println("Customer is not registered");
            return null;
        }

    }

    public Customer createCustomer(Customer newCustomer) {
        return repository.insert(newCustomer);
    }

    public Collection<hotel_reservations> customerUpdateReservation(int id, hotel_reservations newReservation){
        Optional<Customer> customer = repository.findById(id);
        if(customer.isPresent()){
            customer.get().updateNewReservation(newReservation);
            repository.save(customer.get());
            return customer.get().getCustomerReservations();
        }
        else{
            System.out.println("Customer is not registered");
            return null;
        }
    }

    public Collection<hotel_reservations> createNewCustomerReservation(int customerId, hotel_reservations newReservation) {
        Optional<Customer> customer = repository.findById(customerId);
        if(customer.isPresent()){
            customer.get().makeReservation(newReservation);
            repository.save(customer.get());
            return customer.get().getCustomerReservations();
        }
        else{
            System.out.println("Customer is not registered");
            return null;
        }
    }
    public Collection<hotel_reservations> customerDeleteReservation(int id, hotel_reservations newReservation){
        Optional<Customer> customer = repository.findById(id);
        if(customer.isPresent()){
            customer.get().removeReservation(newReservation);
            repository.save(customer.get());
            return customer.get().getCustomerReservations();
        }
        else{
            System.out.println("Customer is not registered");
            return null;
        }
    }
}

Answer 1

Spring 在实现方面使用标准命名约定。

请更正以下内容并检查是否已解决。

1. 将类名hotel重命名为Hotel

2. 将hotel_id 重命名为hotel is

3. 将 hotel_reservations 重命名为 HotelReservations

使用 java 标准命名约定来避免任何异常问题。