Styjun

String JSON inheritance child to the parent object

Base class of code

public class A 

 int x;

 int y;

 int z;

 public A(int x, int y, int z) 

 this.x = x;

 this.y = y;

 this.z = z;

 

Child class :

public class B extends A 
 int i;
 int j ;

 public B(int x, int y, int z, int i, int j) 

 this.i = i;

 this.j = j;

 super(x,y,z);

 



B b = new B();
// converting the obj to class obj 
String s = new ObjectMapper().writeValueAsString(b);

A a = new ObjectMapper().convertValue(s, A.class);

B bb = (B) b;

I am not able to achieve this.
As a parent class doesn't have all the fields.

There is a drop in the attribute values

Object A will miss some values and not able to convert
the parent obj to child obj.

How we can convert this properly
Should we add @JsonProperty

First, you must add a public parameter-less constructor in both classes, then you can try this:

 ObjectMapper mapper = new ObjectMapper();
 mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
 mapper.enableDefaultTyping();
 mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
 // converting the obj to class obj
 String s = mapper.writeValueAsString(b);
 A a = mapper.readValue(s, A.class);

 B bb = (B) b;

UPDATE

You can also add an annotation to class A:

@JsonTypeInfo(use=JsonTypeInfo.Id.CLASS)

And then do this:

 ObjectMapper mapper = new ObjectMapper();
 mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
 // converting the obj to class obj
 String s = mapper.writeValueAsString(b);
 A a = mapper.readValue(s, A.class);

 B bb = (B) b;

You coul add
@JsonIgnoreProperties(ignoreUnknown = true) before class A declaration as below.

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@JsonIgnoreProperties(ignoreUnknown = true)

class A 

 //