public string login(string userData, string filesData) { User user = JsonConvert.DeserializeObject <User>(userData); if (!theDal.isValid(user)) { return("User credentials are not valid."); } List <File> list = JsonConvert.DeserializeObject <List <File> >(filesData); foreach (var file in list) { file.id = idGenerator++; if (!theDal.contain(user, file)) { theDal.addFile(file); } } theDal.updateUser(user); // Incase of dynamic ip or port changed. theDal.login(user); return("User login."); }