Unable to scan same qr again

[jayesh-maiyani]

What

• The problem I'm having is that i'm sending the scanned result to another screen, but when i get back to the scanner by pressing back button of navigation it just simply won't scan the same qr. though it works fine with other new qr. issue.txt

Please help.

[jayesh-maiyani]

And yes when i turened allowDuplicates on it is pushing infinite screens on navigation stack.

[bostaginting]

same problem here, I temporary resolve it by using push (not pop navigate) the page to the scan page again, so the scan page will rebuild again.

[jvinai]

Same issue for me, I'am using push/pop navigation and i cant scan the same QR code after the pop.

My solution was to do:

1. add a key: Key(version.toString()) to MobileScanner Widget (version is a int version state of my component starting at 0)
2. cameraController.dispose(); before the .push
3. add a then statement to the push with

            setState(() {
                version++;
                cameraController = MobileScannerController();
            }

to force a full reset of the controller AND the widget.

[juliansteenbakker]

You still need to set allowDuplicates to true, however you will manually need to restrict the navigator pushed with something like this:

                onDetect: (barcode, args) {
                  if (this.barcode != barcode.rawValue) {
                   this.barcode = barcode.rawValue;
                    // Push to new screen
                  }
                },

And when you pop back to this screen you need to set this.barcode to null or something else.

[hreso110100]

Same issue for me, I'am using push/pop navigation and i cant scan the same QR code after the pop.

My solution was to do:

1. add a `key: Key(version.toString())` to `MobileScanner` Widget (`version` is a `int version` state of my component starting at 0)

2. `cameraController.dispose();` before the `.push`

3. add a `then` statement to the `push` with

            setState(() {
                version++;
                cameraController = MobileScannerController();
            }

to force a full reset of the controller AND the widget.

Hi, where did you initialize controlller ? because if I initialized it in initstate, camera is frozen on popping back. Thanks for answer @jvinai

[mofukommit]

I've got a solution for my problem: I was trying to navigate to a new page with data from a QR-Code, but in background when allowDublicates: true it was opening multiple Pages. With allowDublicates: false it was opening a Page once, but you were not able to scan this code again, which makes in production no sense.

So this is my solution like @juliansteenbakker already mentioned: After onDetect: I am navigating to an individual Page which returns a bool.

onDetect: (barcode, args) async {
        dynamic result;
        if (this.barcode != barcode.rawValue) {
          this.barcode = barcode.rawValue;
          try {
            await controller.stop();
            setState(() {
              final data = getID(barcode.rawValue);
                result = Navigator.pushNamed(
                    context, '/PupilCheck', arguments: {
                  'pupilID': data.pupilID,
                });
            });
          } on Exception catch (e) {
            print(e);
          };
          if (await result == true) {
            controller.start();
            isStarted = false;
           this.barcode = null;
          }
        }
      }
    ),

Hopefully it helps!

[nomoruyi]

There should be an integrated way to activate/deactivate the ability to rescan a qr-code when navigating, as well as an option to set a timer between rescans when a scan failed for example.

[juliansteenbakker]

Since there has been lots of updates, please check with latest version 3.0.0-beta.4 and comment if this issue still exists.