使用JPA的Spring Boot应用程序，具有返回无限递归错误的附加属性的多对多关系

问题描述

由于响应导致错误，因为“无法编写JSON：无限递归（StackOverflowError）”，我试图直接返回实体，我想以两种形式获取响应而无需转换数据。有人可以解决吗？添加实体结构以供参考。

员工实体

print(df)
   index  part_1  part_2  first_ix
0      0       4      11         6
1      1       5      12         4
2      2       6      10         4
3      3       4      12         8
4      4       8      14         6
5      5       4      13         8
6      6       6      11         8
7      7       8      10         4

流实体

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long employeeId;
    private String firstName;
    private String lastName;
    private String role;

    @OnetoMany(mappedBy = "employee")
    private Set<EmployeeStream> streams = new HashSet<>();
}

具有其他属性经验的EmployeeStream实体

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Stream {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long streamId;
    private String streamName;

    @OnetoMany(mappedBy = "stream")
    private Set<EmployeeStream> employees = new HashSet<>();
}

我想以两种形式检索数据

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class EmployeeStream {

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

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "EMPLPOYEE_ID")
    private Employee employee;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "STREAM_ID")
    private Stream stream;

    private double experience;
}

{
  "employeeId": 1,"firstName": "George","lastName": "Stephen","role": "developer","streams": [
    {
      "id": 1,"stream": {
        "streamId": 1,"streamName": "Java"
      },"experience": 1.2
    },{
      "id": 2,"stream": {
        "streamId": 2,"streamName": "Node JS"
      },"experience": 2
    }
  ]
}

解决方法

您需要使用下面的代码中的@JsonBackReference和@JsonManagedReference。

员工实体

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long employeeId;
    private String firstName;
    private String lastName;
    private String role;

    @OneToMany(mappedBy = "employee")
    @JsonManagedReference
    private Set<EmployeeStream> streams = new HashSet<>();
}

流实体

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Stream {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long streamId;
    private String streamName;

    @OneToMany(mappedBy = "stream")
    @JsonManagedReference
    private Set<EmployeeStream> employees = new HashSet<>();
}

EmployeeStream实体

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class EmployeeStream {

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

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "EMPLPOYEE_ID")
    @JsonBackReference
    private Employee employee;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "STREAM_ID")
    @JsonBackReference
    private Stream stream;

    private double experience;
}

您可以找到更多详细信息here和here

更新：以前@JsonBackReference和@JsonManagedReference的位置不正确，更正了相同的地方。

注意：如果仍然遇到任何问题，请尝试从@JsonManagedReference和Stream实体中删除Employee。