spring 引导 REST Api 中的一对多关系

Question

我正在使用 spring 启动来创建 REST API。在这个 API 中，我在 check-in 和 Guests 之间建立了一对多的关系。我创建了一个用于签入的控制器，并使用了 spring JPA 的保存功能。保存方法正在更新 checkin 和 guest tables 但对于来宾 table，客人 table 中的签入外键未被添加，而是显示为空。请有人帮助我。我需要同时创建来宾和签到。

签到模型

@Data
@Entity
public class Checkin {

    @Id
    private Long id;

    private Integer no_of_guests;

    @OneToMany(mappedBy = "checkin", cascade = CascadeType.ALL)
    private List<Guest> guests;
}

来宾模型

@Data
@Entity
public class Guest {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long guest_id;

    private String name;

    private String mobile_no;

    private String address;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "guest_checkin_id", nullable = false )
    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    private Checkin checkin;

}

签到控制器

@RestController
@RequestMapping("/checkin")
public class CheckinController {

    private final CheckinRepository checkinRepo;
    private final GuestRepository guestRepo;

    public CheckinController(CheckinRepository checkinRepo,GuestRepository guestRepo){
        this.checkinRepo = checkinRepo;
        this.guestRepo = guestRepo;
    }

    @PostMapping("/add")
    ResponseEntity<Object> roomCheckin(@RequestBody Checkin checkin){
         if(checkinRepo.save(checkin) != null){
            return ResponseEntity.accepted().body("Checkin Successfull");
        }
        return ResponseEntity.unprocessableEntity().body("Failed to Checkin");
    }
}

Answer 1

使用实体 classes 作为视图模型 classes 可能有点棘手，尤其是在这种情况下 [=18] 之间存在双向一对多关系=] 和 Guest.

让我们从验证实体 classes 和存储库是否如描述的那样工作开始。为了进行测试运行，我必须在 class Checkin.

中为 id 字段添加 @GeneratedValue

其他变化：

使用 Set 而不是 List。参见
对实体 class 使用 @Getter 和 @Setter 而不是 @Data 关系

我在下面添加了一个测试 class CheckinRepositoryTest 以验证代码。

如前所述，使用实体 classes 作为视图模型 classes 可能很棘手，因此下一步将引入两个新的视图模型 classes：CheckinVM 和 GuestVM，以及一个新服务 class GuestService，它将负责保存 Checkin 和 Guest 个实例。代码如下所示。

请注意，我只添加了 GuestService class 的框架，我将其留给您来实现。 CheckinRepositoryTest里面的代码说明了如何实现。

有了视图模型 class，应该删除 @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)。

所有部分都已完成并运行ning，您应该向新视图模型 classes 添加验证，以及一些验证行为的集成测试。如果您遵循 TDD，您将按自己的方式添加测试。

您还应该查看您的控制器方法，并为成功和失败情况使用适当的状态代码。

来宾class

package no.mycompany.myapp.misc;

import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.Getter;
import lombok.Setter;
import javax.persistence.*;

@Getter
@Setter
@Entity
public class Guest {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long guest_id;

    private String name;

    private String mobile_no;

    private String address;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "guest_checkin_id", nullable = false)
    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    private Checkin checkin;
}

GuestVM class

package no.mycompany.myapp.misc;

import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
public class GuestVM {

    private long id;
    private String name;
    private String mobile_no;
    private String address;

    public GuestVM(Guest guest) {
        this.id = guest.getGuest_id();
        this.name = guest.getName();
        this.mobile_no = guest.getMobile_no();
        this.address = guest.getAddress();
    }
}

签到class

package no.mycompany.myapp.misc;

import lombok.Getter;
import lombok.Setter;
import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Getter
@Setter
@Entity
public class Checkin {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private Integer no_of_guests;

    @OneToMany(mappedBy = "checkin", cascade = CascadeType.ALL)
    private Set<Guest> guests = new HashSet<>();
}

CheckinVM class

package no.mycompany.myapp.misc;

import lombok.Getter;
import lombok.Setter;
import lombok.NoArgsConstructor;

import java.util.List;
import java.util.stream.Collectors;

@Getter
@Setter
@NoArgsConstructor
public class CheckinVM {

    private long id;
    private List<GuestVM> guests;

    public CheckinVM(Checkin checkin) {
        this.id = checkin.getId();
        this.guests = checkin.getGuests().stream().map(GuestVM::new).collect(Collectors.toList());
    }
}

签入存储库

package no.mycompany.myapp.misc;

import org.springframework.data.jpa.repository.JpaRepository;

public interface CheckinRepository extends JpaRepository<Checkin, Long> { }

CheckinRepositoryTest

package no.mycompany.myapp.misc;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;

import static org.assertj.core.api.AssertionsForClassTypes.assertThat;

@DataJpaTest
public class CheckinRepositoryTest {

    @Autowired
    TestEntityManager testEntityManager;

    @Autowired
    CheckinRepository checkinRepository;

    @Test
    public void test() {

        // create instances
        var checkinInDb = new Checkin();
        var guestInDb = new Guest();

        // add relations
        guestInDb.setCheckin(checkinInDb);
        checkinInDb.getGuests().add(guestInDb);

        // save check-in
        checkinRepository.save(checkinInDb);

        // verify that check-in has one guest
        var checkin = testEntityManager.find(Checkin.class, checkinInDb.getId());
        assertThat(checkin.getGuests().size()).isEqualTo(1);

        // verify that guest is connected to a check-in
        var guest = testEntityManager.find(Guest.class, guestInDb.getGuest_id());
        assertThat(guest.getCheckin()).isNotNull();
    }
}

CheckinServiceclass: 交给你去实现

package no.mycompany.myapp.misc;

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor
public class CheckinService {

    private final CheckinRepository checkinRepository;

    public CheckinVM saveCheckin(CheckinVM checkin) {
        return null; // TODO: implement this
    }
}

控制器class

package no.mycompany.myapp.misc;

import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/checkin")
@RequiredArgsConstructor
public class CheckinController {

    private final CheckinService checkinService;

    @PostMapping("/add")
    ResponseEntity<Object> roomCheckin(@RequestBody CheckinVM checkin) {
        if (checkinService.saveCheckin(checkin) != null) {
            return ResponseEntity.accepted().body("Checkin Successful");
        }
        return ResponseEntity.unprocessableEntity().body("Failed to Checkin");
    }
}

spring 引导 REST Api 中的一对多关系

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rest

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spring-data-jpa

spring-boot