使用CrudRepository保存带有外键的实体对象

Question

我有两个具有@ManyToOne关系的实体类，如下所示。

@Entity
public class Student {

  @Id
  private Integer studentId;

  @Column(nullable = false)
  private String studentName;

  @ManyToOne(targetEntity = School.class, fetch = FetchType.LAZY, optional = false)
  @JoinColumn(referencedColumnName = "schoolId", insertable = false, updatable = false)
  private School school;

  //Getters and Setters methods

@Entity
public class School {
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Integer schoolId;

  @Column(nullable = false)
  private String schoolName;

  //Getters and Setters methods

[
    {
      "studentId": "2015020",
      "studentName": "ABC",
      "school": {
        "schoolId": 1
      }
    }
]

我是Spring Data JPA的新手，所以这可能是一个非常基本的错误。

Answer 1

在实体student中，属性school是一个对象。若要插入新学生，必须使用对school对象的引用。所以你的有效载荷必须是这样的：

{
    "studentId": 2015020,
    "studentName": "ABC",
    "school": "http://localhost:8080/api/schools/1"
}

还可以简化属性学校的定义：

@ManyToOne(optional = false)
private School school;