为什么我得到 The relevant error-causing widget was: Scaffold?

Question

Hello everyone I want to dispaly some informations inside scaffold but I got The relevant error-causing widget was: Scaffold. Even when I remove it I still got errors:

this is the code:

Widget build(BuildContext context) {
    return Scaffold(
        body: ExpansionTile(
            title: Column(
              mainAxisAlignment: MainAxisAlignment.start,
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Text(
                  widget.model.name,
                  overflow: TextOverflow.ellipsis,
                ),
                Text(
                  widget.model.id.toString(),
                  style: Theme.of(context).textTheme.caption,
                )
              ],
            ),
            leading: SingleChildScrollView(
              child: Column(
                //  children: [
                // Text(widget.model.mtu.toString()),
                children: <Widget>[
                  StreamBuilder(
                    stream: widget.model.mtu,
                    initialData: 0,
                    builder: (c, snapshot) => ListTile(
                      title: const Text('MTU Size'),
                      subtitle: Text('${snapshot.data} bytes'),
                    ),
                    // ],
                  ),
                ],
              ),
            ),
            trailing: TextButton(
              onPressed: () {
                setState(() {
                  buttonText = 'Connecting...';
                });
                widget.viewModel.establishConnectAndEnableNotify(widget.model);
              },
              child: Text(
                buttonText,
                style: TextStyle(color: AppColors.blue),
              ).tr(),
            )));
  }
}

I would be very thankful if you can help me

Answer 1

The issue occurring because of using ListTile , it is trying to get infinite width. You can wrap it with SizedBox and provide width. Using LayoutBuilder on top level will be better to get the parent widget width.

return Scaffold(
    body: LayoutBuilder(
  builder: (_, constraints) => ExpansionTile(
      title: Column(
        mainAxisAlignment: MainAxisAlignment.start,
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[],
      ),
      leading: SingleChildScrollView(
        child: Column(
          //  children: [
          // Text(widget.model.mtu.toString()),
          children: <Widget>[
            StreamBuilder(
              // stream: "widget.model.mtu",
              initialData: 0,
              builder: (c, snapshot) => SizedBox(
                width:
                    constraints.maxWidth * .2, //depend on you or hard-coded value
                child: ListTile(
                  title: Text(' w ${constraints.maxWidth}'),
                  subtitle: Text('${snapshot.data} bytes'),
                ),
              ),
              // ],
            ),
          ],
        ),
      ),

Also, I think you don't want to have SingleChildScrollView on leading , maybe you like to use it on children