如何响应 Spring RestController 返回 ManyToOne 双向 JPA 实体对象？

Question

我有 2 个实体用户和权限，它们具有双向多对一关系。 但是当我发送用户对象作为来自 RestController 的响应时，我得到了嵌套对象 IE。用户{Authority{User{Authority{User{Authority{..}}}}}}

如何实现控制器必须只返回？ 用户{Authority{}}

下面是我的 User 实体类：-

@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long userId;

    private String username;
    private String password;
    private String mobileNo;

    @OneToMany(fetch =FetchType.EAGER , cascade = CascadeType.ALL, mappedBy = "user")
    private Set<Authorities> authorities;
    
    // non-parameterized and parameterized constructor and all getters and setters 

}

@Entity
public class Authorities implements GrantedAuthority {

    private static final long serialVersionUID = -2789840366318513805L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String authority;

    @ManyToOne
    private User user;

    // non-parameterized and parameterized constructor and all getters and setters 
}

@RestController
public class HomeController {
    
    @GetMapping(path = "/home")
    public @ResponseBody User home(@AuthenticationPrincipal User user){
        return user;
    } 
}

以下是我浏览器中的 sn-p：

    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728) ~[jackson-databind-2.12.4.jar:2.12.4]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:770) ~[jackson-databind-2.12.4.jar:2.12.4]

2021-09-18 00:45:17.935 ERROR 9340 --- [nio-8080-exec-7] s.e.ErrorMvcAutoConfiguration$StaticView : Cannot render error page for request [/home] as the response has already been committed. As a result, the response may have the wrong status code.

Answer 1

在Authorities 类中，在User 字段上方添加@JsonIgnore

@ManyToOne
@JsonIgnore
private User user;