Added optional=false to @manytoone

Author: Rajeev Kumar Singh

jpa-one-to-many-demo/src/main/java/com/example/jpa/model/Comment.java

@@ -1,9 +1,10 @@
 package com.example.jpa.model;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.*;
 
 import javax.persistence.*;
 import javax.validation.constraints.NotNull;
+
 import org.hibernate.annotations.OnDelete;
 import org.hibernate.annotations.OnDeleteAction;
 
@@ -21,10 +22,12 @@ public class Comment extends AuditModel {
     @Lob
     private String text;
 
-    @ManyToOne(fetch = FetchType.LAZY)
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
     @JoinColumn(name = "post_id", nullable = false)
     @OnDelete(action = OnDeleteAction.CASCADE)
-    @JsonIgnore
+    @JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
+    @JsonIdentityReference(alwaysAsId=true)
+    @JsonProperty("post_id")
     private Post post;
 
     public Long getId() {