How to deal with parsing JSON response when it contains a dynamic object?

Question

While playing with the JSON parser I encountered a use case (described below in detail) for which using JSON.deserialize(JSONResponse, SampleParent.class) method for parsing doesn't work.

Below is the use case:

public class SampleParent{

    public String a {get;set;}
    public String b {get;set;}
    public String c {get;set;}
    public String d {get;set;}
    public SampleChild test {get;set;}

    public SampleChild{ 
          // in response, for this class doesn't know about the fields. in each and 
          // every response the fields are changing i.e. it is dynamic with no structure
    }

}

How to handle such response using JSON.deserialize and store it in Apex class variable? Actually I want to store such response in String variable.

Response :- 1

{
     "a": "Sometext",
      "b": "Sometext",
       "c": "Sometext",
        "d": "Sometext",
      "test": {
        "Data1": {
          "score": 2
        },
        "Data2": {
          "score1": 1
        },
        "Data3": {
          "score1": 2
        }
      }

 }

Response :- 2

 {
     "a": "Sometext",
      "b": "Sometext",
       "c": "Sometext",
        "d": "Sometext",
      "test": {
        "Data50": {
          "score12": 2
        }       
      }
}

Actually I want to store such response in String variable like a = '{ "Data50": {"score12": 2}}'

Can we handle this use case in Salesforce ?

Any pointers on this would be highly appreciated. Thanks in Advance.

Answer 1

JSON.deserializeUntyped is for doing exactly the type of untyped, dynamic parsing you describe. Your JSON becomes a Map which you navigate (code example included in doc page).

System.JSONParser, as mentioned by tomlogic, would also get you where you need to go although it will probably end up being more code.

Answer 2

Take a look at the System.JSONParser methods, as a way to parse a JSON string one element at a time.