I am developing an industrial app using flutter.
The app involves lot of input from user be it TextFormField or DropDownSearchField.

If user changes/modifies the data/value of any field that is above current field all the data of bellow field must be cleared.

e.g. : If user has set 10 of 12 field numbered (1 to 12), then user decides to change Field 3 then all field bellow Field 3 must be cleared (reset).

I was looking into Switch fallthrough but dart seems to give me error The 'case' should not complete normally. Try adding 'break', or 'return', etc.

I really want to avoid code duplication where by I write clear code in each case. Using if statement is complicating logic.
I looked into solution but I wish to avoid label and continue statement (as this look like goto statement from other languages).

What are my options here?

Code :

void clearDataAfterStepChange({required int step}) {
    switch (step) {
      //Clear All Steps Bellow 1 -> Product Code
      case 1:
        _productCodeController.clear();
      //Clear All Steps Bellow 2 -> Batch Number
      case 2:
        _batchNumberController.clear();
      //Clear All Steps Bellow 3 -> Area
      case 3:
        _areaController.clear();
      //Clear All Steps Bellow 4 -> Room Name
      case 4:
        _roomNumberController.clear();
      //Clear All Steps Bellow 5 -> Stage
      case 5:
        _stageController.clear();
      //Clear All Steps Bellow 6 -> Product Type
      case 6:
        _productTypeController.clear();
      //Clear All Steps Bellow 7 -> Product Name
      case 7:
        _productNameController.clear();
      //Clear All Steps Bellow 8 -> Product Version Number
      case 8:
        _productVersionNumberController.clear();
      //Clear All Steps Bellow 9 -> Version Number
      case 9:
        _versionNumberController.clear();
      //Clear All Steps Bellow 10 -> BMR Number
      case 10:
        _bmrNumberController.clear();
      //Clear All Steps Bellow 11 -> BMR Version Number
      case 11:
        _bmrVersionNumberController.clear();
      //Clear All Steps Bellow 12 -> Process Order Number
      case 12:
        _processOrderNumberController.clear();
      // Do Nothing
      default:
        break;
    } 
}

CodePudding user response：

There's nothing wrong with using continue LABEL. That's what it's there for. (There's also nothing inherently wrong with using goto in C either, and in some common situations it's good form, but I digress.)

However, in your specific case where each step invokes a single zero-argument function¹, you could create a List of callbacks of each of the steps, and then just iterate over them and invoke them:

void clearDataAfterStepChange({required int step}) {
  var steps = <void Function(void)>[
    _productCodeController.clear,
    _batchNumberController.clear,
    _areaController.clear,
    _roomNumberController.clear,
    _stageController.clear,
    _productTypeController.clear,
    _productNameController.clear,
    _productVersionNumberController.clear,
    _versionNumberController.clear,
    _bmrNumberController.clear,
    _bmrVersionNumberController.clear,
    _processOrderNumberController.clear,
  ];
  
  for (var i = step - 1; i >= 0 && i < steps.length; i  = 1) {
    steps[i]();
  }
}

¹ You could still do it even if each step were more complex too, but it would be uglier.

CodePudding user response：

Forget switch statement, it won't solve this problem. So try this way :

 void clearDataAfterStepChange({required int step}) {
     Map<int, TextEditingController> textControllerMap = {
    11: _processOrderNumberController,
    10: _bmrVersionNumberController,
    9: _bmrNumberController,
    8: _versionNumberController,
    7: _productVersionNumberController,
    6: _productNameController,
    5: _productTypeController,
    4: _stageController,
    3: _roomNumberController,
    2: _areaController,
    1: _batchNumberController,
  };

  for (int i = 1; i <= textControllerMap.length; i  ) {
    if (step <= i) {
      textControllerMap[i].clear();
    }
  }
}