为什么不获取映射表数据？

Question

在这种情况下，我试图获取车辆数据。当获取数据但映射的数据不能从中取出时。

这是我的控制器类。

package com.ashen.cdb.cdb_api.controller;

import com.ashen.cdb.cdb_api.model.Vehicle;
import com.ashen.cdb.cdb_api.service.VehicleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@CrossOrigin(maxAge = 3600)
@RestController
public class VehicleController {

    @Autowired
    private VehicleService vehicleService;

    @PostMapping(path = "/vehicle")
    Vehicle addVehicle(@RequestBody Vehicle vehicle){
        return  vehicleService.addVehicle(vehicle);
    }

    @CrossOrigin(origins = "http://localhost:8080")
    @GetMapping(path = "/vehicle")
    Iterable<Vehicle> getAllVehicles(){
        return vehicleService.getAllVehicle();
    }

    @GetMapping(path = "/vehicle/{vehicle_id}")
    Vehicle getVehicle(@PathVariable int vehicle_id){
        return vehicleService.getVehicle(vehicle_id);
    }

}

车辆模型类。

package com.ashen.cdb.cdb_api.model;

import com.fasterxml.jackson.annotation.JsonIgnore;
import org.hibernate.annotations.CreationTimestamp;

import javax.persistence.*;
import java.util.Date;
import java.util.Set;

@Entity
@Table(name = "vehicle")
public class Vehicle {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "vehicle_id")
    private int vehicle_id;

    @Column(name = "vehicle_no")
    private String vehicle_no;

    @Column(name = "vehicle_brand")
    private String vehicle_brand;

    @Column(name = "vehicle_model")
    private String vehicle_model;

    @Column(name = "vehicle_man_year")
    private String vehicle_man_year;

    @Column(name = "vehicle_reg_year")
    private String vehicle_reg_year;

    @Column(name = "vehicle_inventory")
    private String vehicle_inventory;

    @Column(name = "legal_state")
    private int legal_state;

    //sys_user foreign key from user table
    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "user_id",unique = true)
    @JsonIgnore
    private User user;

    @OneToMany(mappedBy = "vehicle", cascade = CascadeType.ALL)
    private Set<BidHistory> bidHistory;

    @Column(name = "created_at")
    @CreationTimestamp
    private Date created_at;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public int getVehicle_id() {
        return vehicle_id;
    }

    public void setVehicle_id(int vehicle_id) {
        this.vehicle_id = vehicle_id;
    }

    public String getVehicle_no() {
        return vehicle_no;
    }

    public void setVehicle_no(String vehicle_no) {
        this.vehicle_no = vehicle_no;
    }

    public String getVehicle_brand() {
        return vehicle_brand;
    }

    public void setVehicle_brand(String vehicle_brand) {
        this.vehicle_brand = vehicle_brand;
    }

    public String getVehicle_model() {
        return vehicle_model;
    }

    public void setVehicle_model(String vehicle_model) {
        this.vehicle_model = vehicle_model;
    }

    public String getVehicle_man_year() {
        return vehicle_man_year;
    }

    public void setVehicle_man_year(String vehicle_man_year) {
        this.vehicle_man_year = vehicle_man_year;
    }

    public String getVehicle_reg_year() {
        return vehicle_reg_year;
    }

    public void setVehicle_reg_year(String vehicle_reg_year) {
        this.vehicle_reg_year = vehicle_reg_year;
    }

    public String getVehicle_inventory() {
        return vehicle_inventory;
    }

    public void setVehicle_inventory(String vehicle_inventory) {
        this.vehicle_inventory = vehicle_inventory;
    }

    public int getLegal_state() {
        return legal_state;
    }

    public void setLegal_state(int legal_state) {
        this.legal_state = legal_state;
    }

    public Date getCreated_at() {
        return created_at;
    }

    public void setCreated_at(Date created_at) {
        this.created_at = created_at;
    }

    public Set<BidHistory> getBidHistory() {
        return bidHistory;
    }

    public void setBidHistory(Set<BidHistory> bidHistory) {
        this.bidHistory = bidHistory;
    }
}

车辆存储库层。

package com.ashen.cdb.cdb_api.repository;

import com.ashen.cdb.cdb_api.model.Vehicle;
import org.springframework.data.repository.CrudRepository;

public interface VehicleRepository extends CrudRepository<Vehicle, Integer> {

}

VehcileService类别

package com.ashen.cdb.cdb_api.service;

import com.ashen.cdb.cdb_api.model.Vehicle;

public interface VehicleService {

    Iterable<Vehicle> getAllVehicle();

    Vehicle addVehicle(Vehicle vehicle);

    Vehicle getVehicle(Integer vehicle_id);
}

VehicleServiceImple类

package com.ashen.cdb.cdb_api.service;

import com.ashen.cdb.cdb_api.model.Vehicle;
import com.ashen.cdb.cdb_api.repository.VehicleRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class VehicleServiceimpl implements VehicleService{

    @Autowired
    private VehicleRepository vehicleRepository;

    @Override
    public Vehicle addVehicle(Vehicle vehicle){
        return vehicleRepository.save(vehicle);
    }

    @Override
    public Vehicle getVehicle(Integer vehicle_id){
        return null;
    }

    @Override
    public Iterable<Vehicle> getAllVehicle(){
        return vehicleRepository.findAll();
    }
}

这是输出。

    [
  {
    "vehicle_id": 1,
    "vehicle_no": "CDS 1259",
    "vehicle_brand": "Toyota",
    "vehicle_model": "Xtrail",
    "vehicle_man_year": "2018",
    "vehicle_reg_year": "2019",
    "vehicle_inventory": null,
    "legal_state": 1,
    "bidHistory": [],
    "created_at": "2020-03-22T07:32:51.000+0000"
  }
]

此处的bidHistory []数据应从bidHistory类获取。但是这组是空的。