调用 JpaRepository.getById() 后的结果实体不包含调用 JpaRepository.saveAndFlush() 后带有 @JoinColumn 的字段的值

Question

当我保存一个具有引用另一个实体的 @JoinColumn 字段的实体时，它会通过调用 saveAndFlush() 按预期正确保存。现在，我希望能够 return 此实体及其相关实体返回给用户。我假设使用新保存实体的 ID 调用 getById() 也会检索 returned 实体中的 @JoinColumn 值，但是，returned 实体的相关实体包含与 saveAndFlush() 中使用的相关实体完全相同的值。我已经制作了示例代码来演示我在说什么。

我发送请求： GET http://localhost:8080 并收到回复：

{
  "id": 3,
  "name": "tests",
  "related": {
    "id": 3,
    "name": null
  }
}

我的目标是获得相同的请求return以下响应：

{
  "id": 3,
  "name": "tests",
  "related": {
    "id": 3,
    "name": "test"
  }
}

其中 related 包含 name 以及 saveAndFlush() 中指定的 id。

Controller.java

import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequiredArgsConstructor
public class Controller {

    private final ObjectRepository oRepo;
    private final RelatedObjectRepository coRepo;

    @GetMapping
    private Object test() {
        // imagine as if this entity is already present in the database before this request is handled, this line is only for context.
        RelatedObject co = coRepo.saveAndFlush(new RelatedObject(null, "test"));
        
        // create an instance of RelatedObject to contain the value for the related_id foreign key column.
        RelatedObject nco = new RelatedObject(co.getId(), null);
        // create Object and save it along with the referenced RelatedObject.
        Object o = oRepo.saveAndFlush(new Object(null, "tests", nco));

        // I expected all values of 'co' object to be contained in the result here in the @JoinColumn field 'related' of Object, instead, only 'id' is present like the 'nco' object
        return oRepo.getById(o.getId());
    }
}

Object.java

import lombok.*;

import javax.persistence.*;

@Table(name = "object")
@Entity
@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
public class Object {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Long id;

    @Column(name = "name", length = 100)
    private String name;

    @ManyToOne
    @JoinColumn(name = "related_id")
    private RelatedObject related;

}

相关Object.java

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

import javax.persistence.*;

@Table(name = "related_object")
@Entity
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class RelatedObject {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "Id", nullable = false)
    private Long id;

    @Column(name = "name", length = 100)
    private String name;
}

ObjectRepository.java

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

public interface ObjectRepository extends JpaRepository<Object, Long> {
}

相关ObjectRepository.java

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

public interface RelatedObjectRepository extends JpaRepository<RelatedObject, Long> {
}

SpringPlayGroundApplication.java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringPlayGroundApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringPlayGroundApplication.class, args);
    }

}

Answer 1

好的，我知道我需要什么了。

关联实体需要级联刷新，例如：

@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.REFRESH)
@JoinColumn(name = "parent_id")
private Category parent;

调用 JpaRepository.getById() 后的结果实体不包含调用 JpaRepository.saveAndFlush() 后带有 @JoinColumn 的字段的值

The result entity after calling JpaRepository.getById() does not contain values for fields with @JoinColumn after calling JpaRepository.saveAndFlush()

spring-data

spring-data-jpa

spring-boot