Umapathi :
Forum Answer saving time facing issue.before i saved successfully using @JsonIgnore but now i removed @JsonIgnore annonation.and added @JsonBackReference and @JsonManagedReference.
Stack Trace
java.lang.IllegalArgumentException: Can not handle managed/back reference 'defaultReference': back reference type (java.util.List) not compatible with managed type (com.tta.abcd.model.ForumAnswerReplay)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase._resolveManagedReferenceProperty(BeanDeserializerBase.java:790)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.resolve(BeanDeserializerBase.java:516)
at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:296)
at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
at com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
at com.fasterxml.jackson.databind.DeserializationContext.findContextualValueDeserializer(DeserializationContext.java:443)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.createContextual(CollectionDeserializer.java:196)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.createContextual(CollectionDeserializer.java:26)
at com.fasterxml.jackson.databind.DeserializationContext.handleSecondaryContextualization(DeserializationContext.java:681)
at com.fasterxml.jackson.databind.DeserializationContext.findContextualValueDeserializer(DeserializationContext.java:445)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.findDeserializer(StdDeserializer.java:967)
Forum.java
@Entity
@Table(name="Forum")
public class Forum {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="forumId")
private Long forumId;
@Column(name="question")
private String question;
@Column(columnDefinition="varchar(1000)",name="discription")
private String discription;
@Column(name="postedDate")
private Date postedDate;
@Fetch(value = FetchMode.SELECT)
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "forumId")
@JsonIgnore
private List<ForumAnswer> forumList;
}
ForumAnswer.java
@Entity
@Table(name="ForumAnswer")
public class ForumAnswer {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="forumAnswerId")
private Long forumAnswerId;
@ManyToOne
@JoinColumn(name = "forumId",insertable=true, updatable=true,nullable=true)
private Forum forum;
@Column(name="answer")
private String answer;
@Column(name="answerDate")
private Date answerDate;
@Fetch(value = FetchMode.SELECT)
@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "forumAnswerId")
@JsonBackReference
private List<ForumAnswerReplay> forumAnswerReplayList;
@Transient
private List<ForumAnswerReplay> faqReplayList;
}
ForumAnswerReplay.java
@Entity
@Table(name="ForumAnswerReplay")
public class ForumAnswerReplay {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="replayId")
private Long replayId;
@Column(name="replayToAnswer")
private String replayToAnswer;
@Column(name="replayToAnswerDate")
private Date replayToAnswerDate;
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="forumAnswerId",insertable=true,updatable=true,nullable=true)
@JsonManagedReference
private ForumAnswer forumAnswer;
@Transient
private String message;
}
Controller Code:
public ForumAnswer saveForumAns(@RequestBody ForumAnswer forumAns, BindingResult bindingResult, HttpSession session,
HttpServletRequest request, HttpServletResponse response) {
ForumAnswer forumDetails = forumService.saveForumAns(forumAns, bindingResult, session);
if (forumDetails != null) {
forumDetails.setMessage("success");
}
else {
forumDetails.setMessage("failed");
}
return forumDetails;
}
DAO:
public ForumAnswer saveForumAns(ForumAnswer forumAns, BindingResult bindingResult) {
final Session session = getSession();
try {
session.beginTransaction();
Query query = session.createQuery("UPDATE ForumAnswer set answer =:answer,"
+ "forumAnswerId =:forumAnswerId,farmerUuid =:farmerUuid, answerDate =:answerDate");
query.setParameter("answer", forumAns.getAnswer());
query.setParameter("forumAnswerId", forumAns.getForumAnswerId());
query.setParameter("farmerUuid", forumAns.getFarmer());
query.setParameter("answerDate", forumAns.getAnswerDate());
session.merge(forumAns);
session.getTransaction().commit();
} catch (Exception e) {
e.printStackTrace();
System.out.println("error while saving forum details" + e);
} finally {
session.close();
}
return forumAns;
}
dhyanandra singh :
I think you have misplaced @JsonManagedReference and @JsonBackReference.
@JsonManagedReference : its forward part of reference so it will apply on collection type.
@JsonBackReference: its back part of reference.
so your code must be like
@JsonManagedReference
private List<ForumAnswerReplay> forumAnswerReplayList;
@JsonBackReference
private ForumAnswer forumAnswer;
you can also use @JsonIdentityInfo you have to apply
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "forumAnswerId",
scope = Long.class)
public class ForumAnswer {
}
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "replyId",
scope = Long.class)
public class ForumAnswerReplay {
}
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