public void AddUpdateContact(string name, string category, string phoneNumber, string emailAddress)
 {
     if (dataModel.NameIsValid(name) == false)
     {
         mainView.DisplayErrorMessage("The name is invalid");
         return;
     }
     if (dataModel.EmailAddressIsValid(emailAddress) == false)
     {
         mainView.DisplayErrorMessage("The email address is invalid");
         return;
     }
     dataModel.AddUpdateContact(name, category, phoneNumber, emailAddress);
     mainView.AddUpdateContactInGrid(name, category, phoneNumber, emailAddress);
 }