Can not attach SnappingSheetController

[maitycyrus]

I always get the error:

SnappingSheet must be attached before calling any function from the controller. Pass in the controller to the snapping sheet widget to attached. Use [isAttached] to check if it is attached or not.
'package:snapping_sheet/src/snapping_sheet_widget.dart':
Failed assertion: line 418 pos 7: 'isAttached'

Also, I think there is a mistake in your readme of how to attach the SnappingSheetController. You call the constructor of the controller twice. I tried it both way, and it did not work.

[redmacdev1988]

I have the code set up like the example and I got the same error maitycyrus mentioned:
"SnappingSheet must be attached before calling any function from the controller".

I readjusted my code where I then

1. create the SnappingSheetController()
2. create the SnappingSheet, and attach the controller

`
@OverRide
void initState() {

_snappingSheetController = SnappingSheetController();

this.sheet = SnappingSheet(
  controller: _snappingSheetController, // snappingSheetController attached here
  snappingPositions: [
    SnappingPosition.factor(
      positionFactor: POSITION_FACTOR_START,

...
...
}`

Now I"m getting a Null check operator on a null value error:

[VERBOSE-2:ui_dart_state.cc(186)] Unhandled Exception: Null check operator used on a null value
#0 _SnappingSheetState.sheetSize
package:snapping_sheet/src/snapping_sheet_widget.dart:307
#1 _SnappingSheetState.initState..
package:snapping_sheet/src/snapping_sheet_widget.dart:192
#2 State.setState
package:flutter/…/widgets/framework.dart:1267
#3 _SnappingSheetState.initState.
package:snapping_sheet/src/snapping_sheet_widget.dart:190
#4 _rootRunUnary (dart:async/zone.dart:1362:47)
#5 _CustomZone.runUnary (dart:async/zone.dart:1265:19)
#6 _FutureListener.handleValue (dart:async/future_impl.dart:152:18)
#7 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:704:45)
#8 Future._propagateToListeners (dart:async/future_impl.dart:733:32)
#9 Future._complete (dart:async/future_impl.dart:530:7)
#10 new Future.delayed. (dart:async/future.<…>

[AdamJonsson]

@maitycyrus You are right regarding the fault in the README, you should pass in the variable instead of creating a new controller. If you got the time, could you send the code for when you are using the controller?

@redmacdev1988 Seems that I can not replicate the error. Could you send the code for the entire widget that contains the SnappingSheet widget and uses the controller?

[maitycyrus]

import 'package:flutter/material.dart';
import 'package:snapping_sheet/snapping_sheet.dart';

void main() {
runApp(MyApp());
}

class MyApp extends StatelessWidget {
// This widget is the root of your application.
@OverRide
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(

    primarySwatch: Colors.blue,
  ),
  home: MyHomePage(title: 'Flutter Demo Home Page'),
);

}
}

class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);

final String title;

@OverRide
_MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State {

@OverRide
Widget build(BuildContext context) {

SnappingSheetController snappingSheetController = SnappingSheetController();
return Scaffold(
  appBar: AppBar(

    title: Text(widget.title),
  ),
  body: SnappingSheet(
    // Connect it to the SnappingSheet
    controller: snappingSheetController,

    grabbingHeight: 200,
    grabbing: GestureDetector(
      onTap: (){
        print('Controller is not working!');
        snappingSheetController.snapToPosition(
          SnappingPosition.factor(positionFactor: 0.75),
        );
      },
      child: Container(
        height: 200,
          color: Colors.blue
      ),
    ),
    sheetBelow: SnappingSheetContent(
      draggable: true,
      child: Container(color: Colors.red),
    ),
  ), // This trailing comma makes auto-formatting nicer for build methods.
);

}
}

[maitycyrus]

... code reproducing the bug

[Lix-ai]

Same error, same everything

[maitycyrus]

I think the problem is the initState method in _SnappingSheetState it does not get called when hot reloading. It works if I run on restart.

[akbarpulatov]

Can you check my PR #74? I checked with the example above, everything is working fine now.