Listening to a text controller inside Riverpod

[2kjm]

I want to listen to a textcontroller and dispatch an action if it's empty. While I try to implement inside initstate i get a Badstate error. What is the right way to do this?

[msarkrish]

@2kjm Can you post the error you have received?

[2kjm]

Another exception was thrown: Bad state: Tried to read a provider from a ProviderContainer that was already disposed

[msarkrish]

Can you post your sample code?

[mark8044]

Without some code its hard to say what the exact issue is, but my goto general solution for state situations is to wrap a ref.read inside a postFrameCallBack, for better or worse

                WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                              ref.read(provider)....
                    });

[tbm98]

use ref.read instead of watch

[2kjm]

Tried it with ref.read but still getting error

my code
@override void initState() { widget.textController.addListener(() { if (widget.textController.text.isEmpty) { ref.read(messageComposerProvider.notifier).setIsComposing(false); } else { ref .read(messageComposerProvider.notifier) .setNoOfLinesInTextField(widget.textController.text); ref.read(messageComposerProvider.notifier).setIsComposing(true); } }); super.initState(); }

my error:

`══╡ EXCEPTION CAUGHT BY FOUNDATION LIBRARY ╞════════════════════════════════════════════════════════
The following assertion was thrown while dispatching notifications for TextEditingController:
Looking up a deactivated widget's ancestor is unsafe.
At this point the state of the widget's element tree is no longer stable.
To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by
calling dependOnInheritedWidgetOfExactType() in the widget's didChangeDependencies() method.

When the exception was thrown, this was the stack:
#0 Element._debugCheckStateIsActiveForAncestorLookup. (package:flutter/src/widgets/framework.dart:4186:9)
#1 Element._debugCheckStateIsActiveForAncestorLookup (package:flutter/src/widgets/framework.dart:4200:6)
#2 Element.getElementForInheritedWidgetOfExactType (package:flutter/src/widgets/framework.dart:4226:12)
#3 ProviderScope.containerOf (package:flutter_riverpod/src/framework.dart:97:12)
#4 ConsumerStatefulElement.read (package:flutter_riverpod/src/consumer.dart:487:26)
#5 _TextMessageComposerState.initState. (package:message_composer/text_message_composer.dart:22:13)
#6 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:324:24)
#7 ValueNotifier.value= (package:flutter/src/foundation/change_notifier.dart:428:5)
#8 TextEditingController.value= (package:flutter/src/widgets/editable_text.dart:159:11)
#9 EditableTextState._value= (package:flutter/src/widgets/editable_text.dart:2211:23)
#10 EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:2617:5)
#11 EditableTextState.userUpdateTextEditingValue (package:flutter/src/widgets/editable_text.dart:2919:5)
#12 RenderEditable._setTextEditingValue (package:flutter/src/rendering/editable.dart:710:27)
#13 RenderEditable._setSelection (package:flutter/src/rendering/editable.dart:729:5)
#14 RenderEditable.selectWordEdge (package:flutter/src/rendering/editable.dart:2011:5)
#15 TextSelectionGestureDetectorBuilder.onSingleTapUp (package:flutter/src/widgets/text_selection.dart:1539:30)
#16 _TextFieldSelectionGestureDetectorBuilder.onSingleTapUp (package:flutter/src/material/text_field.dart:89:11)
#17 _TextSelectionGestureDetectorState._handleTapUp (package:flutter/src/widgets/text_selection.dart:1966:29)
#18 TapGestureRecognizer.handleTapUp. (package:flutter/src/gestures/tap.dart:611:57)
#19 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:198:24)
#20 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:611:11)
#21 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:298:5)
#22 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:269:7)
#23 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:157:27)
#24 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:449:20)
#25 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:425:22)
#26 RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:329:11)
#27 GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:380:7)
#28 GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:344:5)
#29 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:302:7)
#30 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:285:7)
#34 _invoke1 (dart:ui/hooks.dart:170:10)
#35 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:331:7)
#36 _dispatchPointerDataPacket (dart:ui/hooks.dart:94:31)
(elided 3 frames from dart:async)

The TextEditingController sending notification was:
TextEditingController#d2b7c(TextEditingValue(text: ┤├, selection: TextSelection.collapsed(offset:
0, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end:
-1)))
════════════════════════════════════════════════════════════════════════════════════════════════════`

[mark8044]

@2kjm Why not try what I mentioned and put it inside a postFrameCallback?

@override void initState() { 
widget.textController.addListener(() { 
if (widget.textController.text.isEmpty) 
{ 
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                              ref.read(messageComposerProvider.notifier).setIsComposing(false); 
                    });
} 
else 
{ 
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
ref .read(messageComposerProvider.notifier) .setNoOfLinesInTextField(widget.textController.text); ref.read(messageComposerProvider.notifier).setIsComposing(true); 
                    });
} 
}); 
super.initState(); 
}

[2kjm]

Thanks man. It worked

[XuanTung95]

@2kjm

The following assertion was thrown while dispatching notifications for TextEditingController:
Looking up a deactivated widget's ancestor is unsafe.
At this point the state of the widget's element tree is no longer stable.
To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by

I think this exception occurs because you use textController.addListener but do not remove it, and textController remain after the ConsumerState is disposed, hence the old listener causes the exception. I think creating TextEditingController outside of State and passing it around can cause hidden bugs, should avoid.