REST Assured Tutorial 39 – @JsonIgnore Annotation of Jackson API - Exclude Field of Pojo From Serialization and Deserialization

As a part of End to End REST Assured Tutorial, in this post, We will learn about an important annotation called @JsonIgnore of Jackson library which helps in restricting properties of a POJO class from serialization and deserialization.

Table of Contents

Prerequisite

Since we are using Jackson API of Java for this example, make sure you have the latest dependency of Jackson Databind in your project classpath. I have used below Jackson dependency for this post:-

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.11.1</version>
</dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

There may be multiple fields in a Pojo class and sometimes you don’t require some fields to participate in serialization and deserialization process. I can give a scenario where we may need to ignore some properties of a Pojo class.

In a POJO class, we may have properties whose values are derived from other properties. For example- If we know the first name and last name of a person we can get their full name. If we know the age of a person we can get to know if a person is eligible for the vote or not. We can have getter methods for such properties to return values but should not be allowed to set from outside.

Consider below POJO.

package JacksonTutorials;

public class EmployeePojoWithoutJsonIgnore {

	// private variables or data members of pojo class
	private String firstName;
	private String lastName;
	private String gender;
	private int age;
	private double salary;
	private boolean married;
	
	private String fullName;
	private boolean eligibleForVote;
	
	// Getter and setter methods
	public String getFirstName() {
		return firstName;
	}
	
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public double getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
	public boolean getMarried() {
		return married;
	}
	public void setMarried(boolean married) {
		this.married = married;
	} 
	
	public String getFullName() {
		return this.fullName;
	}
	public boolean getEligibleForVote() {
		return this.eligibleForVote;
	}

	public void setFullName(String fullName) {
		this.fullName = fullName;
	}

	public void setEligibleForVote(boolean eligibleForVote) {
		this.eligibleForVote = eligibleForVote;
	}
	
	
}

package JacksonTutorials;

public class EmployeePojoWithoutJsonIgnore {

// private variables or data members of pojo class

private String firstName;

private String lastName;

private String gender;

private int age;

private double salary;

private boolean married;

private String fullName;

private boolean eligibleForVote;

// Getter and setter methods

public String getFirstName() {

return firstName;

}

public void setFirstName(String firstName) {

this.firstName = firstName;

}

public String getLastName() {

return lastName;

}

public void setLastName(String lastName) {

this.lastName = lastName;

}

public String getGender() {

return gender;

}

public void setGender(String gender) {

this.gender = gender;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public double getSalary() {

return salary;

}

public void setSalary(double salary) {

this.salary = salary;

}

public boolean getMarried() {

return married;

}

public void setMarried(boolean married) {

this.married = married;

}

public String getFullName() {

return this.fullName;

}

public boolean getEligibleForVote() {

return this.eligibleForVote;

}

public void setFullName(String fullName) {

this.fullName = fullName;

}

public void setEligibleForVote(boolean eligibleForVote) {

this.eligibleForVote = eligibleForVote;

}

Serialization using above POJO

@Test
	public void serializationWithoutJsonIgnore() throws JsonProcessingException {
		// Just create an object of Pojo class
		EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore = new EmployeePojoWithoutJsonIgnore();
		employeePojoWithoutJsonIgnore.setFirstName("Amod");
		employeePojoWithoutJsonIgnore.setLastName("Mahajan");
		employeePojoWithoutJsonIgnore.setAge(29);
		employeePojoWithoutJsonIgnore.setGender("Male");
		employeePojoWithoutJsonIgnore.setSalary(12323.56);
		employeePojoWithoutJsonIgnore.setMarried(false);
		employeePojoWithoutJsonIgnore.setFullName("Animesh Prashant");
		employeePojoWithoutJsonIgnore.setEligibleForVote(false);

		// Converting a Java class object to a JSON payload as string
		ObjectMapper objectMapper = new ObjectMapper();
		String employeeJson = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(employeePojoWithoutJsonIgnore);
		System.out.println("Serialization...");
		System.out.println(employeeJson);
	}

@Test

public void serializationWithoutJsonIgnore() throws JsonProcessingException {

// Just create an object of Pojo class

EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore = new EmployeePojoWithoutJsonIgnore();

employeePojoWithoutJsonIgnore.setFirstName("Amod");

employeePojoWithoutJsonIgnore.setLastName("Mahajan");

employeePojoWithoutJsonIgnore.setAge(29);

employeePojoWithoutJsonIgnore.setGender("Male");

employeePojoWithoutJsonIgnore.setSalary(12323.56);

employeePojoWithoutJsonIgnore.setMarried(false);

employeePojoWithoutJsonIgnore.setFullName("Animesh Prashant");

employeePojoWithoutJsonIgnore.setEligibleForVote(false);

// Converting a Java class object to a JSON payload as string

ObjectMapper objectMapper = new ObjectMapper();

String employeeJson = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(employeePojoWithoutJsonIgnore);

System.out.println("Serialization...");

System.out.println(employeeJson);

}

Output

Serialization...
{
  "firstName" : "Amod",
  "lastName" : "Mahajan",
  "gender" : "Male",
  "age" : 29,
  "salary" : 12323.56,
  "married" : false,
  "fullName" : "Animesh Prashant",
  "eligibleForVote" : false
}

Serialization...

{

"firstName" : "Amod",

"lastName" : "Mahajan",

"gender" : "Male",

"age" : 29,

"salary" : 12323.56,

"married" : false,

"fullName" : "Animesh Prashant",

"eligibleForVote" : false

}

Deserialization using above POJO

@Test
	public void deserializationWithoutJsonIgnore() throws JsonMappingException, JsonProcessingException
	{
		String employeeString = "{\r\n" + 
				"  \"firstName\" : \"Amod\",\r\n" + 
				"  \"lastName\" : \"Mahajan\",\r\n" + 
				"  \"gender\" : \"Male\",\r\n" + 
				"  \"age\" : 29,\r\n" + 
				"  \"salary\" : 12323.56,\r\n" + 
				"  \"married\" : false,\r\n" + 
				"  \"fullName\" : \"Amod Mahajan Gupta\",\r\n" + 
				"  \"eligibleForVote\" : false\r\n" + 
				"}";
		
		ObjectMapper objectMapper = new ObjectMapper();
		EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore2 = objectMapper.readValue(employeeString, EmployeePojoWithoutJsonIgnore.class);
		System.out.println("Deserialization...");
		System.out.println("First name :- "+employeePojoWithoutJsonIgnore2.getFirstName());
		System.out.println("Last name :- "+employeePojoWithoutJsonIgnore2.getLastName());
		System.out.println("Age :- "+employeePojoWithoutJsonIgnore2.getAge());
		System.out.println("Gender :- "+employeePojoWithoutJsonIgnore2.getGender());
		System.out.println("Salary :- "+employeePojoWithoutJsonIgnore2.getSalary());
		System.out.println("Married :- "+employeePojoWithoutJsonIgnore2.getMarried());
		System.out.println("Eligible for vote :- "+employeePojoWithoutJsonIgnore2.getEligibleForVote());
		System.out.println("Full name :- "+employeePojoWithoutJsonIgnore2.getFullName());
	}

@Test

public void deserializationWithoutJsonIgnore() throws JsonMappingException, JsonProcessingException

{

String employeeString = "{\r\n" +

" \"firstName\" : \"Amod\",\r\n" +

" \"lastName\" : \"Mahajan\",\r\n" +

" \"gender\" : \"Male\",\r\n" +

" \"age\" : 29,\r\n" +

" \"salary\" : 12323.56,\r\n" +

" \"married\" : false,\r\n" +

" \"fullName\" : \"Amod Mahajan Gupta\",\r\n" +

" \"eligibleForVote\" : false\r\n" +

"}";

ObjectMapper objectMapper = new ObjectMapper();

EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore2 = objectMapper.readValue(employeeString, EmployeePojoWithoutJsonIgnore.class);

System.out.println("Deserialization...");

System.out.println("First name :- "+employeePojoWithoutJsonIgnore2.getFirstName());

System.out.println("Last name :- "+employeePojoWithoutJsonIgnore2.getLastName());

System.out.println("Age :- "+employeePojoWithoutJsonIgnore2.getAge());

System.out.println("Gender :- "+employeePojoWithoutJsonIgnore2.getGender());

System.out.println("Salary :- "+employeePojoWithoutJsonIgnore2.getSalary());

System.out.println("Married :- "+employeePojoWithoutJsonIgnore2.getMarried());

System.out.println("Eligible for vote :- "+employeePojoWithoutJsonIgnore2.getEligibleForVote());

System.out.println("Full name :- "+employeePojoWithoutJsonIgnore2.getFullName());

}

Output:-

Deserialization...
First name :- Amod
Last name :- Mahajan
Age :- 29
Gender :- Male
Salary :- 12323.56
Married :- false
Eligible for vote :- false
Full name :- Amod Mahajan Gupta

Deserialization...

First name :- Amod

Last name :- Mahajan

Age :- 29

Gender :- Male

Salary :- 12323.56

Married :- false

Eligible for vote :- false

Full name :- Amod Mahajan Gupta

If you observe output carefully we see values of properties of “fullName” and “eligibleForVote” have set wrongly. We should have calculated it. Ideally, these fields should have getter methods only just for quick access.

Complete Program

package JacksonTutorials;

import org.testng.annotations.Test;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class SerialiDeserialExampleWithoutJsonIgnore {

	@Test
	public void serializationWithoutJsonIgnore() throws JsonProcessingException {
		// Just create an object of Pojo class
		EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore = new EmployeePojoWithoutJsonIgnore();
		employeePojoWithoutJsonIgnore.setFirstName("Amod");
		employeePojoWithoutJsonIgnore.setLastName("Mahajan");
		employeePojoWithoutJsonIgnore.setAge(29);
		employeePojoWithoutJsonIgnore.setGender("Male");
		employeePojoWithoutJsonIgnore.setSalary(12323.56);
		employeePojoWithoutJsonIgnore.setMarried(false);
		employeePojoWithoutJsonIgnore.setFullName("Animesh Prashant");
		employeePojoWithoutJsonIgnore.setEligibleForVote(false);

		// Converting a Java class object to a JSON payload as string
		ObjectMapper objectMapper = new ObjectMapper();
		String employeeJson = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(employeePojoWithoutJsonIgnore);
		System.out.println("Serialization...");
		System.out.println(employeeJson);
	}
	
	@Test
	public void deserializationWithoutJsonIgnore() throws JsonMappingException, JsonProcessingException
	{
		String employeeString = "{\r\n" + 
				"  \"firstName\" : \"Amod\",\r\n" + 
				"  \"lastName\" : \"Mahajan\",\r\n" + 
				"  \"gender\" : \"Male\",\r\n" + 
				"  \"age\" : 29,\r\n" + 
				"  \"salary\" : 12323.56,\r\n" + 
				"  \"married\" : false,\r\n" + 
				"  \"fullName\" : \"Amod Mahajan Gupta\",\r\n" + 
				"  \"eligibleForVote\" : false\r\n" + 
				"}";
		
		ObjectMapper objectMapper = new ObjectMapper();
		EmployeePojoWithoutJsonIgnore employeePojoWithoutJsonIgnore2 = objectMapper.readValue(employeeString, EmployeePojoWithoutJsonIgnore.class);
		System.out.println("Deserialization...");
		System.out.println("First name :- "+employeePojoWithoutJsonIgnore2.getFirstName());
		System.out.println("Last name :- "+employeePojoWithoutJsonIgnore2.getLastName());
		System.out.println("Age :- "+employeePojoWithoutJsonIgnore2.getAge());
		System.out.println("Gender :- "+employeePojoWithoutJsonIgnore2.getGender());
		System.out.println("Salary :- "+employeePojoWithoutJsonIgnore2.getSalary());
		System.out.println("Married :- "+employeePojoWithoutJsonIgnore2.getMarried());
		System.out.println("Eligible for vote :- "+employeePojoWithoutJsonIgnore2.getEligibleForVote());
		System.out.println("Full name :- "+employeePojoWithoutJsonIgnore2.getFullName());
	}
}

package JacksonTutorials;

import org.testng.annotations.Test;

import com.fasterxml.jackson.core.JsonProcessingException;

import com.fasterxml.jackson.databind.JsonMappingException;

import com.fasterxml.jackson.databind.ObjectMapper;

public class SerialiDeserialExampleWithoutJsonIgnore {