I am trying to parse the below response but im getting the following error FATAL_ERROR System.TypeException: Invalid conversion from runtime type Map<String,ANY> to Map<String,List> Can someone tell me how to parse it? I haven't used any wrapper class though but when i use the map.get I just get one value instead of a list of values.

//String jsonInput2='{"UserDetails":[{"ContactLastName":"TestAcc","ContactFirstName":"TheLandlord","IsActive":true,"ContactRecordTypeId":"0120C000001OpcIQAS","ContactId":"0030C00000TLabQQAT","AccountId":"0010C00000ToNO9QAN"}]}';
Map<string,list<object>> strObjMap= new Map<string,list<object>>();
Map<string,list<object>>  obj = (Map<string,list<object>>)JSON.deserializeUntyped(jsonInput);
system.debug('Obj data >>>'+obj.values().size());

1 Answer 1


The only types you can cast to when using deserializeUntyped are:

  • Object
  • Map<String, Object>
  • List<Object>
  • String
  • Boolean
  • Decimal
  • Integer
  • Double

And then, only if it is actually a compatible data type.

So, for example, your code might look like:

Map<String, Object> parsedJson = (Map<String, Object>)JSON.deserializeUntyped(jsonInput2);
List<Object> userDetails = (List<Object>)parsedJSON.get('UserDetails');
for(Object userDetail: userDetails) {
  Map<String, Object> detail = (Map<String, Object>)userDetail;

If you want to get that data type, you can use a specific shape, as follows:

Map<String, List<Object>> parsedJson = 
  (Map<String, List<Object>>)
  JSON.deserialize(jsonInput2, Map<String, List<Object>>.class);

Or even:

Map<String, List<Map<String, Object>>> parsedJson = 
  (Map<String, List<Map<String, Object>>>)
    Map<String, List<Map<String, Object>>>.class

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