Apex - get values in nested JSON

Question

I have some JSON being returned, but getting the values deeply nested is very annoying.

{  
"Result":"1",
"Matches":[  
  {  
     "BioInformation":{  
        "BirthDate":"1987-09-13T05:00:00",
        "SSN":"123456789",
        "Sex":"M"
        "UserID":"116713"
     },
     "IdInformation":{  
        "ChangeIndicator":null,
        "DataOrigin":"WebServices",
        "EntityIndicator":"P",
        "FirstName":"Test",
        "mID":"921821621",
        "LastName":"B",
        "MiddleName":null,
        "RowID":"AAAYGXBBAXAF8mZAA6",
        "SurnamePrefix":null,
        "UserID":null
     },
     "UniqueId":"AAg9eAAACAAA9eBAAA"
  },
  {  
     "BioInformation":{  
        "ConfidInd":false,
        "SSN":"123456789",
        "Sex":"N",
        "UserID":"155064"
     },
     "IdInformation":{  
        "ChangeIndicator":null,
        "DataOrigin":"WebServices",
        "EntityIndicator":"P",
        "FirstName":"Steven",
        "mID":"921821721",
        "LastName":"Johnson",
        "MiddleName":null,
        "RowID":"AADFAAKFJAA3dZDD3",
        "SurnamePrefix":null,
        "UserID":"TEST123"
     },
     "UniqueId":"AAg9eAAACAAA9eBAAB"
  }
 ]
}

I have something like:

Map<String, Object> m = (Map<String, Object>) JSON.deserializeUntyped(body); 
List<Object> matches = (List<Object>) m.get('Matches');

if (matches != null) {
    for (Object match : matches) {
        for (Object data : match) {

         }
         System.debug('match : ' + match);
    }      
}

Is there a good/easy/efficient way to access the inside information such as BirthDate, RowID, etc?

Answer 1

Use serialization/deserialization and it's quite easy. You can generate the definitions using JSON2Apex, but it's not rocket surgery and I typically prefer to do it by hand. For example you might do:

public class MyPayload
{
    public class Result
    {
        public final String uniqueId;
        public final IdInformation idInformation;
        public final BioInformation bioInformation;
    }
    public class BioInformation
    {
        final Boolean confidInd;
        final String ssn, sex, userId;
    }
    public class IdInformation
    {
        final String changeIndicator, dataOrigin, entityIndicator, mID, rowId, userId;
        final String firstName, lastName, middleName, surnamePrefix;
    }
}

Then it's easy to work with the results.

List<MyPayload.Result> results = (List<MyPayload.Result>)JSON.deserialize(
    somePayload, List<MyPayload.Result>.class
);
for (MyPayload.Result result : results)
{
    system.debug(result.idInformation.firstName);
}

Answer 2

If you don't know about the keys and values of JSON response then we need to look for other options so I added this approach to get keys and value of JSON response into map<key, value>. Reusable method to get nested objects by giving property and JSON response as a string into apex method.

Sample Data :

{
"Application": 
{ 
"email": "sa", "name": "sasa", "first_name": "sasa", "last_name": "", "phone_number": "915", "normalized_phone_number": "+9s5", 
"data": { "key1": "resumekey", "key2":"true", "key3":"false" } 
}
}

if you want to access nested data key and its value you can use this reusable approach.Please find below code.

---

---

public static Map<string,String> fetchApplicantNestedProperty(String keyToExtract,String jsonStringResponse,String parentString)
        { 
    //keyToExtract - data
   // jsonStringResponse - the json response after converting into string 
//parentString - applicant is parent key

  Map<string,String> subPropertyMap = new Map<String,String>(); 
        Map<String,Object> deserializedApplicantObjectMap =(Map<String,Object>) JSON.deserializeUntyped(jsonStringFromFountain);//jsonresponse string into map<key,object>
    System.debug('parentString'+parentString+':::'+deserializedApplicantObjectMap.get(parentString));
   
         System.debug('applicantObjectMap'+deserializedApplicantObjectMap); 
    Map<String,Object> ParsedApplicantMap=(Map<String,Object>)deserializedApplicantObjectMap.get(parentString); //applicant
    
    for(String applicantKey:ParsedApplicantMap.keySet())
     { 
    if(applicantKey==keyToExtract){ // key==data 
    System.debug('applicantkey'+applicantKey+'===>'+ParsedApplicantMap.get(applicantKey));
    
    Map<String,Object> applicantNestedPropertiesMap=(Map<String,Object>)ParsedApplicantMap.get(keyToExtract); //datakey example
    
    System.debug('applicantNestedPropertiesMap'+applicantNestedPropertiesMap); 
    
    for(String subPropertyKey:applicantNestedPropertiesMap.keySet()) //iterate data object key and value
    { //iterate data object key and its values 
    System.debug('dk'+subPropertyKey+'==>'+applicantNestedPropertiesMap.get(subPropertyKey)); 
    subPropertyMap.put(subPropertyKey,String.valueOf(applicantNestedPropertiesMap.get(subPropertyKey)));
     } 
    break; 
    } 
    } 
    return subPropertyMap; //return the nested object data as map<key,value>
    }