detect delete soft keyboard on flutter

Question

I created custom TextField widget :

class ActionTextField extends StatefulWidget {
  final String label;
  final String errorText;
  final FocusNode focusNode;...

const ActionTextField(
  {Key key,
  this.label,
  this.focusNode,...

 child: Column(
        children: [
          Material(
            elevation: 1.5,
            shadowColor: Colors.grey,
            child: Stack(
              children: [
                TextField(
                  textAlignVertical: TextAlignVertical.center,
                  obscureText: widget.isPassword,
                  focusNode: widget.focusNode,
                  controller: widget.controller ?? widget.controller,

Now I am using my widget into my project.Now i need to detect delete soft keyboard so in order to i use RawKeyboardListener according it's official page.

  final FocusNode _focusNode = FocusNode();

  void _handleKeyEvent(RawKeyEvent event) {
    print("0000000000");
    if (event.logicalKey == LogicalKeyboardKey.delete) {
      //do whatever you have to do
      print("0000000000");
    }
  }

Widget build(BuildContext context) {...
  RawKeyboardListener(
    focusNode: _focusNode,
    onKey: _handleKeyEvent,
    child: ActionTextField(
      label: "Test",
      focusNode: _focusNode,

But when i passed _focusNode into my custom view i got error:

════════ Exception caught by widgets library ═══════════════════════════════════
Tried to make a child into a parent of itself.
'package:flutter/src/widgets/focus_manager.dart':
Failed assertion: line 959 pos 12: 'child != this'
The relevant error-causing widget was
    TextField 

And when i comment _focusNode from my custom view, I can not detect my key from softkeyboard!!! How can i detect delete soft keyboard ?

Answer 1

The problem is that you use the same FocusNode object in parent and child widgets. You need to exclude TextField from RawKeyboardListener widget, for example:

@override
Widget build(BuildContext context) {
  final focusNode = FocusNode();

  return Scaffold(
    body: SafeArea(
      child: Row(
        children: [
          RawKeyboardListener(
            focusNode: focusNode,
            child: const SizedBox.shrink(),
            onKey: (e) => print(e),
          ),
          Expanded(
            child: TextField(
              focusNode: focusNode,
            ),
          )
        ],
      ),
    ),
  );
}

In this case you will able to handle keyboard events in RawKeyboardListener and TextField will handle same events by self.

In some cases after handling event in RawKeyboardListener TextField loses focus. I use the following workaround to return focus to TextField:

onKey: (e) {
  // Some code for event handling

  // W/A for TextField focus loss
  textFieldFocusNode.previousFocus();
  SchedulerBinding.instance.scheduleFrameCallback((_) {
    textFieldFocusNode.nextFocus();
  });
},