Flutter: want to clean data when pressing back button or pressing a button

Question

I want to clean data when i press a button which takes me to next page or backbutton which also clean the data. But when i go back to same page the data is still there and it is not back to init page. Right now, my code look something like this:

import 'package:flutter/material.dart';

DateTime _dateFrom;
DateTime _dateTo;

bool _checked = false;

class ItemDetail extends StatelessWidget{
  var someVariable1 = "something";
  var someVariable2 = "Something elser";
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      //Some widgets here
      //_DateTimePickerAndCheckBox is also used here
    );
  }
}

class _DateTimePickerAndCheckBox extends StatefulWidget
{
  @override
  State<StatefulWidget> createState() => _DateTimePickerAndCheckBoxState();
  
}

class _DateTimePickerAndCheckBoxState extends State<_DateTimePickerAndCheckBox>
{
  @override
  Widget build(BuildContext context)
  {
    return Column(); //More widgets here
  }
  
}

All I want is to remove _dateFrom and _dateTo because it is used for stateful widget and later used for stateless widget.

Answer 1

You are declaring variables outside of any classes, so the value you change will also be stored here.

DateTime _dateFrom;
DateTime _dateTo;

class ItemDetail extends StatelessWidget {} ...

Option 1 : You can declare it inside of ItemDetail class.

class ItemDetail extends StatelessWidget {
    DateTime _dateFrom;
    DateTime _dateTo;
}

Option 2

Or if you have several classes in this file which depends on it, create a custom class on its on, and use it. Objects will be created and disposed automatically depending on the screen state.

class _DateTime{
 DateTime from;
 DateTime to;
}

To use it, create a _DateTime object when you want

_DateTime dateTime = _DateTime();
dateTime.from = ... // your code here
dateTime.to = ... // your code here

Remember to pass the object to child widget if you want to use the same object later.

WARNING. You need to have a good understanding on how to pass data between widgets, such as from parents to child, and child to parents.

A good method will be using some state management tool , such as Provider.

Option 3

This is not the proper solution, but just a smart hack, you don't need to change anything in your code, except replacing the close button method with:

onPressed/ontap : () {
 _dateFrom = null;
 _dateTo = null;
 Navigator.of(context).pop();
}