Removing a node in json in Java

Question

Given the following json:

{
   "User":{
      "firstname":"john",
      "gender":"female",
      "verified":"no"
   }
}

Is there a way to remove/ignore "User" node so I can use the jackson bind ? You see, at the moment if I try and do this:

User user= mapper.readValue(content, User.class); //where content is the json above

where User class is:

public class User
{
     String _firstname, _gender, _verified;

     [getters and setters]
}

it gives an error saying:

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "User"

I know I can just initialise the User class and just do setters manually but I was wondering if it is possible or better to remove/ignore the "User" node instead?

trying to understand why would you want that

Ashish
– Ashish

2013-12-26 21:20:47 +00:00
Commented Dec 26, 2013 at 21:20 — Ashish
– Ashish, Commented Dec 26, 2013 at 21:20
Its so I can bind the json to the user class.

obsessiveCookie
– obsessiveCookie

2013-12-26 22:15:45 +00:00
Commented Dec 26, 2013 at 22:15 — obsessiveCookie
– obsessiveCookie, Commented Dec 26, 2013 at 22:15

Sotirios Delimanolis · Accepted Answer · 2013-12-26 21:27:54Z

3

In the root of your JSON, you have another JSON object named User. You can't just ignore it since it contains the object you are trying to extract. What you need to do is extract the object from that nested JSON object instead of the root JSON object.

You can do that by getting the nested JSON object.

ObjectMapper mapper = new ObjectMapper(); 
JsonNode node = mapper.readTree(content);
User user = mapper.readValue(node.get("User").traverse(), User.class);

Also, I'm not sure if Jackson supports dangling , as you have at the end of

"verified":"no",

edited Dec 26, 2013 at 21:27

answered Dec 26, 2013 at 21:21

Sotirios Delimanolis

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1 Comment

obsessiveCookie Over a year ago

Hi your answer worked as well but Kevin's answer made more sense to me. Thank you also for noticing the , ! I have edited my question accordingly.

Kevin Bowersox · Accepted Answer · 2013-12-26 21:47:47Z

This solution uses pure Jackson by setting the rootName on the ObjectReader:

import java.io.IOException;

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

public class User {

    public static void main(String[] args) throws JsonProcessingException, IOException {

        String json = "{\"User\":{\"firstname\":\"john\",\"gender\":\"female\",\"verified\":\"no\"}}";
        ObjectMapper mapper = new ObjectMapper();
        ObjectReader reader = mapper.reader(User.class).withRootName("User");
        User user = reader.readValue(json);

        System.out.println(user.getFirstname());
    }

    private String firstname;
    private String lastname;
    private String verified;
    private String gender;

    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 getVerified() {
        return verified;
    }

    public void setVerified(String verified) {
        this.verified = verified;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

}

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