How to get specific object from RestTemplate excha

Question

I have an end-point which returns me this response:

{
  "head": {
    "status": 200,
    "ok": true,
    "messages": [],
    "errors": [],
    "references": {}
  },
  "body": {
    "id": "d57a9c7aef9842c2e31a0f49c",
    "flowId": "f57979d06f9842c3e94f1f197",
    "creationDate": 1470744494732,
    "path": "/luafanti/test",
    "version": 0,
    "elems": {
      "xxx": {
        "type": "integer",
        "value": 200
      }
    }
  }
}

My question is, how to make a model that can be populated with only a part of my json response. For example, with this:

 "xxx": {
            "type": "integer",
            "value": 200
        }

or this:

"elems": {
          "xxx": {
            "type": "integer",
            "value": 200
          }
        }

Answer 1

Using Jackson, you can define your model as the following:

@JsonIgnoreProperties(ignoreUnknown=true)
public class MyResponseModel {
  private Body body;

  public void setBody(Body body) {this.body = body;}
  public Body getBody() {return body;}

  @JsonIgnoreProperties(ignoreUnknown=true)
  public static class Body {
    private Elems elems;
    // getter and setter for elems 
  }

  @JsonIgnoreProperties(ignoreUnknown=true)
  public static class Elems {
    private Xxx xxx;
    // getter and setter for xxx 
  }

  @JsonIgnoreProperties(ignoreUnknown=true)
  public static class Xxx {
    private String type;
    private String value;

    // getter and setter for type and value 
  }
}

The above is quite verbose, particularly if you are only interested in a very small part of the response. It may be more practical to handle the response as a String and then use e.g. JsonPath to extract only the data you are interested in.

Answer 2

You can use simple-json.jar to extract that object from inside the JSONObject

Downloadable Jar Link - simple-json.jar Download Link

Maven Jar Import Maven Repository pom syntax

You actual object is

  {
  "head": {
    "status": 200,
    "ok": true,
    "messages": [],
    "errors": [],
    "references": {}
  },
  "body": {
    "id": "d57a9c7aef9842c2e31a0f49c",
    "flowId": "f57979d06f9842c3e94f1f197",
    "creationDate": 1470744494732,
    "path": "/luafanti/test",
    "version": 0,
    "elems": {
      "xxx": {
        "type": "integer",
        "value": 200
      }
    }
  }
} // hold this complete object in any string reference Variable.

Here I Suppose String jsonString holds the complete json object as above described.

import org.json.simple.parser.JSONParser; 
import org.json.simple.parser.JSONObject;

// implemetation logic for extracting jsonObject.

private JSONObject extractFirstBlock(String jsonString) throws ......{

   JSONObject jsonObj ;

   JSONParser parser=new JSONParser();  // parser to parse string to JSONObject
   jsonObj = (JSONObject) parser.parse(jsonString); // parse the Object using parse Method.
  String desiredObject = (String) jsonObj.get("body"); // this Object contains your desired output which you wish to receive.

   jsonObj = parser.parse(desiredObject);
   desiredObject = jsonObj.get("elems"); // you will get your desired object as you expected.
}

Here in desiredObject you will get your expected Values as JSONObject.

 "xxx": {
            "type": "integer",
            "value": 200
        }