convert json to string

Question

Trialhead Apex REST Callouts challenge https://developer.salesforce.com/trailhead/apex_integration_services/apex_integration_rest_callouts

Hi i am very new to salesforce and has statred learning through Trialhead. I am in the REST callouts section. I started it but i don't know how to get the response. i am not sure if i am going about this right. This is my first time even seeing a http service. please any help or guidance would be appreciated. i have pasted my code here .. I get an error that an object cannot be assigned to a string. if i change the type of result to object , the error goes away.I am not sure how to convert it back to a string.

public class AnimalLocator {

    public static String getAnimalNameById(Integer id){
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals/:id');
        request.setMethod('GET');
        HttpResponse response = http.send(request);

        // check the response
      if (response.getStatusCode() == 200)
      {
           String result = JSON.deserializeUntyped(response.getBody());

      }//end of if
            return null;
    }//end of method
    }//end of class

Answer 1

When you use JSON.deserializeUntyped(Object) method you must type-cast it to expected type always. Assuming that you are expecting String type so, statement should be like:

String result = (String)JSON.deserializeUntyped(response.getBody());

Alternative but not always recommended

String result = String.valueOf( JSON.deserializeUntyped(response.getBody()) );

Another one which does not require even type casting:

String result = JSON.deserialize(response.getBody(), String.class);

Answer 2

Type-cast it into string

String result = (String)JSON.deserializeUntyped(response.getBody());

then it should avoid the compilation error. Basically what we are doing is that, we convert the result of JSON.deserializeUntyped() into a string and then store it inside the 'result' variable(which is already a string type reference).

Answer 3

String strjson = response.getbody();
Map<String,Object> newMapObj = Map<String,Object>JSON.deserializeUntyped(strjson );