How to ignore a json field and get its value to map using Jackson ObjectMapper

Question

Given the below json

  {
    "countries":{
        "country":[{
            "name":"USA",
             "independence":"July 4, 1776",
         }],
     },
  }

I will like to ignore "countries" and get the value of country instead. hence, after mapping my json should look as so

{
  "countries": [{
            "name":"USA",
             "independence":"July 4, 1776",
         }],
 }

Is this currently possible with ObjectMapper?

EDIT: below are the Pojo

public class Result {
private static final long serialVersionUID = 6403654749443599206L;

@Getter @Setter @JsonProperty("country") private List<Country> countries;
}

public class Country {
private static final long serialVersionUID = 6403654749443599206L;

@Getter @Setter private String name;
@Getter @Setter private String independence;
}

and I am doing this

    return new ObjectMapper().readValue({jsonValue}, Result.class);

@CássioMazzochiMolin return mapper.readValue({jsonValue}, {pojo.class}); — user3137376, Feb 14 '17 at 18:48

score 0 · Answer 1 · answered Feb 14 '17 at 19:05

The input json has a wrong syntax. It should be like this

  {
    "countries":{
        "country":[{
            "name":"USA",
             "independence":"July 4, 1776"
         }]
     }
  }

ObjectMapper is used to turn json into Object and Object into json. Anyway, to convert the first json to the other you desire you can do something like this:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.io.IOException;
import java.util.List;

public class ConvertExample {

    public static void main(String[]args) {

        String inputJson = new String("{\"countries\":{\"country\":[{\"name\":\"USA\", \"independence\":\"July 4, 1776\"}]}}");

        ObjectMapper mapper = new ObjectMapper();
        mapper.enable(SerializationFeature.INDENT_OUTPUT); //To indent output, optional
        try {
            StartPojo startPojo = mapper.readValue(inputJson, StartPojo.class);
            EndPojo endPojo = new EndPojo();
            endPojo.countries = startPojo.getCountries().getCountry();
            String outputJson = mapper.writeValueAsString(endPojo);

            System.out.println("Output:");
            System.out.println(outputJson);

        } catch (IOException e) {
            e.printStackTrace(); //Cannot read the input json
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class StartPojo {
        private Countries countries;

        public Countries getCountries() {
            return countries;
        }

        public void setCountries(Countries countries) {
            this.countries = countries;
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class EndPojo {
        private List<Country> countries;

        public List<Country> getCountries() {
            return countries;
        }

        public void setCountries(List<Country> countries) {
            this.countries = countries;
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class Countries {
        private List<Country> country;

        public List<Country> getCountry() {
            return country;
        }

        public void setCountry(List<Country> country) {
            this.country = country;
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class Country {
        private String name;
        private String independence;

        public String getName() {
            return name;
        }

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

        public String getIndependence() {
            return independence;
        }

        public void setIndependence(String independence) {
            this.independence = independence;
        }
    }
}

This class takes the input json and convert it to the other format by printing it into the console. The ouput of this code is:

{
  "countries" : [ {
    "name" : "USA",
    "independence" : "July 4, 1776"
  } ]
}

How to ignore a json field and get its value to map using Jackson ObjectMapper

1 Answers1