My flutter Post request is not sending the parameters to server. Whenever I check for the variables from the server I see NULL. I have tried a lot of options and I can’t seem to get it to work. Here is my code:

Future<void> listRecentCashTransactions() async{
 try{
   var res = await http.post(
       Uri.parse(API.recentCashTransactionURL),
       body: {
           'userID': userID.toString(),
           'sessionData': sessionData.toString(),
       },
   );
   if(res.statusCode==200){
       final resBody = jsonDecode(res.body);
       final sessionDataX = resBody['checkUserID'];
       int userXID = resBody['checkUserID'];

       print("User ID before API call : $userID");
       print("User ID after API call : $userXID");
       print("Session Data before API call : $sessionDataX");
       print("Session data after : $sessionDataX");
   }   
 }
 catch(e){
   print(e.toString());
 }
}