Jackson @JsonView examples

In Jackson, we can use @JsonView to limit or control fields display for different users.

A POJO for testing.

Staff.java

package com.favtuts.json.jsonviews;

import java.math.BigDecimal;
import java.util.List;
import java.util.Map;

public class Staff {
      
    private String name;
    private int age;
    private String[] position;
    private List<String> skills;
    private Map<String, BigDecimal> salary;

    public Staff(String name, int age) {
        this.name = name;
        this.age = age;        
    }

    public Staff() {
    }

	// getters , setters , boring stuff

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return this.age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String[] getPosition() {
        return this.position;
    }

    public void setPosition(String[] position) {
        this.position = position;
    }

    public List<String> getSkills() {
        return this.skills;
    }

    public void setSkills(List<String> skills) {
        this.skills = skills;
    }

    public Map<String,BigDecimal> getSalary() {
        return this.salary;
    }

    public void setSalary(Map<String,BigDecimal> salary) {
        this.salary = salary;
    }
}

P.S Tested with Jackson 2.9.8

1. Views

A standard Java class to define 3 views: normal, manager and hr.

CompanyViews.java

package com.favtuts.json.jsonviews;

public class CompanyViews {

    public static class Normal{};

    public static class Manager extends Normal{};

    public static class HR extends Normal{};
    
}

2. Json View

Puts @JsonView on field level to limit fields display for different views.

• Normal – display name and age.
• Manager – display name, age, position and skills
• HR – display name, age, salary and position

P.S Manager has no right to view the salary field, and HR doesn’t care what skills you have 🙂

Staff.java

package com.favtuts.json.jsonviews;

import java.math.BigDecimal;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonView;

public class Staff {

    @JsonView(CompanyViews.Normal.class)
    private String name;

    @JsonView(CompanyViews.Normal.class)
    private int age;

    // two views
    @JsonView({CompanyViews.HR.class, CompanyViews.Manager.class})
    private String[] position;

    @JsonView(CompanyViews.Manager.class)
    private List<String> skills;

    @JsonView(CompanyViews.HR.class)
    private Map<String, BigDecimal> salary;

3. Jackson – Enable the @JsonView

3.1 Below example, show you how to enable the JsonView with mapper.writerWithView()

JacksonExample.java

package com.favtuts.json;

import java.io.IOException;
import java.math.BigDecimal;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.favtuts.json.jsonviews.CompanyViews;
import com.favtuts.json.jsonviews.Staff;

public class JacksonJsonViews {

    public static void main(String[] args) {
        enableJsonView();
    }

    static void enableJsonView() {

        ObjectMapper mapper = new ObjectMapper();

        Staff staff = createStaff();

        try {

            // to enable pretty print
            mapper.enable(SerializationFeature.INDENT_OUTPUT);

            // normal
            String normalView = mapper.writerWithView(CompanyViews.Normal.class).writeValueAsString(staff);

            System.out.format("Normal views\n%s\n", normalView);

            // manager
            String managerView = mapper.writerWithView(CompanyViews.Manager.class).writeValueAsString(staff);

            System.out.format("Manager views\n%s\n", managerView);

            // hr
            String hrView = mapper.writerWithView(CompanyViews.HR.class).writeValueAsString(staff);

            System.out.format("HR views\n%s\n", hrView);

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private static Staff createStaff() {

        Staff staff = new Staff();

        staff.setName("favtuts");
        staff.setAge(38);
        staff.setPosition(new String[] { "Founder", "CTO", "Writer" });
        Map<String, BigDecimal> salary = new HashMap() {
            {
                put("2010", new BigDecimal(10000));
                put("2012", new BigDecimal(12000));
                put("2018", new BigDecimal(14000));
            }
        };
        staff.setSalary(salary);
        staff.setSkills(Arrays.asList("java", "python", "node", "kotlin"));

        return staff;

    }
}

Output

Normal views
{
  "name" : "favtuts",
  "age" : 38
}
Manager views
{
  "name" : "favtuts",
  "age" : 38,
  "position" : [ "Founder", "CTO", "Writer" ],
  "skills" : [ "java", "python", "node", "kotlin" ]
}
HR views
{
  "name" : "favtuts",
  "age" : 38,
  "position" : [ "Founder", "CTO", "Writer" ],
  "salary" : {
    "2018" : 14000,
    "2012" : 12000,
    "2010" : 10000
  }
}

Download Source Code

$ git clone https://github.com/favtuts/java-core-tutorials-examples

$ cd java-basic/json

References

• Jackson – How to ignore null fields
• Jackson data-binding
• Jackson 2 – Convert Java Object to / from JSON