Java Jackson：多个反向引用属性，名称为“defaultReference”
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Hymanson: Multiple back-reference properties with name 'defaultReference'
提问by Kien Dang Ngoc
I'm trying to map a json (string format) to an object and I get the following error
我正在尝试将 json（字符串格式）映射到一个对象，但出现以下错误
com.fasterxml.Hymanson.databind.JsonMappingException: Multiple back-reference properties with name 'defaultReference'
com.fasterxml.Hymanson.databind.JsonMappingException：具有名称“defaultReference”的多个反向引用属性
This is the json string
这是json字符串
{"pledge":"74","client":"66","date":"","originId":"1","qualityId":"2","grade":"19","packing":"4","tons":"1000","fromDate":"","toDate":"","type":0,"remark":"","status":0,"area":"1531","id":-1,"refNumber":"","log":"","user":""}
This is the object
这是对象
@Entity
@Table(name="movement", catalog = "wsmill3")
public class MovementView implements java.io.Serializable {
private Integer id;
private Integer originId;
private Integer qualityId;
private String refNumber;
private Integer client;
private String clientRef;
private Integer grade;
private Integer packing;
private Integer pledge;
private Integer area;
private Date date;
private Double tons;
private Date fromDate;
private Date toDate;
private String remark;
private User user;
private Byte status;
private String log;
private Byte type;
//constructor, getter and setter
and this is the code to do mapping
这是做映射的代码
String data = request.getParameter("data");
ObjectMapper mapper = new ObjectMapper();
MovementView movement = mapper.readValue(data, MovementView.class);
I have no idea with this error, I did exact the same way as I read on Hymanson homepage. Anyone who knows about it, please help me
我不知道这个错误，我的做法和我在Hyman逊主页上读到的完全一样。哪位知道的请帮帮我
回答by stephen
If you use @JsonBackReference on your getter/setter method in your project more than twice,you should distinguish them with a specific Reference name.Maybe only one 'defaultReference' is allowed in the latest version.
如果你在你的项目中的 getter/setter 方法上使用 @JsonBackReference 超过两次，你应该用一个特定的引用名称来区分它们。也许最新版本中只允许一个“defaultReference”。
e.g
例如
in MovementView.class
在 MovementView.class 中
@JsonBackReference(value="user-movement")
public User getUser() {
return user;
}
in User.class
在 User.class 中
@JsonManagedReference(value="user-movement")
public User getMovementView() {
return movementView;
}
回答by Vivek Gangwar
I also faced this issue, but resolved it.
我也遇到过这个问题，不过解决了。
//This is parent class
@Entity
@Table(name = "checklist")
@JsonIgnoreProperties("inspection")
public class Checklist implements java.io.Serializable {
@ManyToOne
@JoinColumn(name = "product_id", referencedColumnName = "id")
@JsonBackReference
private Product product;
@OneToMany(mappedBy = "checklists", cascade = CascadeType.ALL)
@JsonManagedReference
private Set<Inspection> inspection = new HashSet<Inspection>();
//Constructor
//Getter and Setter
}
//This is child class
@Entity
@Table(name = "inspections")
public class Inspection {
@ManyToOne
@JoinColumn(name = "chk_id", referencedColumnName = "id")
private Checklist checklists;
//Constructor
//Getter and Setter
}
By mentioning @JsonIgnoreProperties("inspection")and @JsonManagedReference.
通过提及@JsonIgnoreProperties("inspection")和@JsonManagedReference。
Resolved the issue raised by using two @JSONBackRefrencein same parent class.
解决了@JSONBackRefrence在同一个父类中使用两个引起的问题。
回答by Gayan Prasanna
I think the best way to handle this is using @JsonIdentityInfo annotation.see the thread which demonstrate this.How to use @JsonIdentityInfo with circular references?
我认为处理这个问题的最好方法是使用 @JsonIdentityInfo 注释。请参阅演示这一点的线程。如何将@JsonIdentityInfo 与循环引用一起使用？
