How to define alternate names to a field using Jackson in Java?

The @JsonAlias annotation can define one or more alternate names for the attributes accepted during the deserialization, setting the JSON data to a Java object. But when serializing, i.e. getting JSON from a Java object, only the actual logical property name is used instead of the alias.

Syntax

@Target(value={ANNOTATION_TYPE,FIELD,METHOD,PARAMETER})
@Retention(value=RUNTIME)
public @interface JsonAlias

Example

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import java.io.*;
public class ObjectToJsonTest {
   public static void main(String[] args) throws JsonProcessingException {
      ObjectMapper mapper = new ObjectMapper();
      Technology tech = new Technology("Java", "Oracle");
      Employee emp = new Employee(110, "Raja", tech);
      String jsonWriter = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(emp);
      System.out.println(jsonWriter);
   }
}
// Technology class
class Technology {
   @JsonProperty("skill")
   private String skill;
   @JsonProperty("subSkill")
   @JsonAlias({"sSkill", "mySubSkill"})
   private String subSkill;
   public Technology(){}
   public Technology(String skill, String subSkill) {
      this.skill = skill;
      this.subSkill = subSkill;
   }
   public String getSkill() {
      return skill;
   }
   public void setSkill(String skill) {
      this.skill = skill;
   }
   public String getSubSkill() {
      return subSkill;
   }
   public void setSubSkill(String subSkill) {
      this.subSkill = subSkill;
   }
}
// Employee class
class Employee {
   @JsonProperty("empId")
   private Integer id;
   @JsonProperty("empName")
   @JsonAlias({"ename", "myename"})
   private String name;
   @JsonProperty("empTechnology")
   private Technology tech;
   public Employee(){}
   public Employee(Integer id, String name, Technology tech){
      this.id = id;
      this.name = name;
      this.tech = tech;
   }
   public Integer getId() {
      return id;
   }
   public void setId(Integer id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public Technology getTechnology() {
      return tech;
   }
   public void setTechnology(Technology tech) {
      this.tech = tech;
   }
}

Output

{
 "technology" : {
 "skill" : "Java",
 "subSkill" : "Oracle"
 },
 "empId" : 110,
 "empName" : "Raja",
 "empTechnology" : {
 "skill" : "Java",
 "subSkill" : "Oracle"
 }
}

raja

Updated on: 17-Feb-2020

4K+ Views

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