Any way to show a snackBar once per stateful page build?

Question

I want to show SnackBar pop-up once per build of a certain stateful page. This is a Flutter web project. Any help will be appreciated.

`once per build` when widget update or on just when ever build methods get called? — Md. Yeasin Sheikh, Jun 03 '22 at 14:08
Either ways is cool as I'm adding this only for landing page — Delwinn, Jun 03 '22 at 14:09

score 0 · Answer 1 · answered Jun 03 '22 at 13:07

0

i guess this is what you meant

Stafeful Widget {
    Widget build() {
       showsnackbar()
       return someWIdget();
   }

answered Jun 03 '22 at 13:07

Sanketh B. K

759
8
22

1

ty for your time, but I fixed it. And this will probably give out an error about setState() called before build() – Delwinn Jun 03 '22 at 13:31
i see, the context will not have scaffold, as it's not built yet – Sanketh B. K Jun 03 '22 at 13:59
Yes, lmk if you have any alternative. – Delwinn Jun 03 '22 at 14:08

Md. Yeasin Sheikh · Answer 2 · 2022-06-04T04:44:23.503

0

Basically, I am using .addPostFrameCallback it will show after the frame is build.

 _showSnackBar() {
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text("SnackBar")));
    });
  }

And place _showSnackBar() inside initState show snackeBar once.

  @override
  void initState() {
    super.initState();
     _showSnackBar();
  }

And place _showSnackBar() under build method to show snackeBar every build

  Widget build(BuildContext context) {
    _showSnackBar();
    ......

edited Jun 04 '22 at 04:44

answered Jun 03 '22 at 14:15

Md. Yeasin Sheikh

54,221
7
29
56

I tried this on flutter web, the snackbar keeps on popping up all the time. – Delwinn Jun 03 '22 at 16:45
It is because build method can call multiple times. If you just want single time snack bar, place `_showSnackBar();` inside initState. – Md. Yeasin Sheikh Jun 03 '22 at 17:25
initstate wouldn't have the scaffold context,will raise an error. My try did – Delwinn Jun 04 '22 at 03:30
Did you run it? It will get context because of `addPostFrameCallback`. – Md. Yeasin Sheikh Jun 04 '22 at 04:40

score 0 · Answer 3 · answered Jun 04 '22 at 08:00

This is an alternative

bool snackBarShowed = false; in top-level code

I put this inside the build method

if (snackBarShowed) {
    } else {
      Future.delayed(Duration.zero, () {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
            action: SnackBarAction(
              label: 'Ok',
              onPressed: () {
                ScaffoldMessenger.of(context).hideCurrentSnackBar();
              },
            ),
            backgroundColor: Colors.black87,
            content: Text(
              'Use top-left logo to move to previous screen',
              style: body.copyWith(
                color: Colors.white,
              ),
            )));
      });
      snackBarShowed = true;
    }

Any way to show a snackBar once per stateful page build?

3 Answers3