Could not find a Portal above this PortalTarget when using OpenContainer animation

[jamesncl]

I'm using flutter_portal 1.1.4 with the animations package from flutter.dev.

If I use a PortalFollower in combination with an OpenContainer (aka 'container transform', which provides a nice transition animation when pushing a route), when the container opens, I get:

The following PortalNotFoundError was thrown building _PortalTargetVisibilityBuilder(visible: false, closeDuration: null, builder: Closure: (BuildContext, bool) => Widget, dirty, state: _PortalTargetVisibilityBuilderState#7635b):
Error: Could not find a Portal above this PortalTarget(debugName: null, portalCandidateLabels=[[String <'test'>]]).

The relevant error-causing widget was:
PortalTarget PortalTarget:file:///Users/james/GithubRepos/portal_bug/lib/main.dart:48:18
When the exception was thrown, this was the stack:
0 _PortalTargetState.build. (package:flutter_portal/src/portal_target.dart:265:11)
1 _PortalTargetVisibilityBuilderState.build (package:flutter_portal/src/portal_target.dart:449:26)

I think that during the transition animation, PortalTarget cannot find a PortalLinkScope

        // From portal_target.dart line 263:
        final scope = PortalLinkScope.of(context, widget.portalCandidateLabels);
        if (scope == null) {
          throw PortalNotFoundError._(widget);
        }

I think because the animation detatches the whole widget from the original context to do the animation to the new route. This error occurs even if I set visibility to false on PortalTarget before triggering the animation.

I guess this is more a problem with the animations package but it would be nice if it could not throw an error if PortalLinkScope is not found but visibility is false, for example:

        final scope = PortalLinkScope.of(context, widget.portalCandidateLabels);
        if (scope == null) {
          // Add this check:
          if(widget.visible) {
            throw PortalNotFoundError._(widget);
          }
          else {
            return Container();
          }
        }

Here's a minimal reproducible example, just tap the button to trigger the error:

import 'package:animations/animations.dart';
import 'package:flutter/material.dart';
import 'package:flutter_portal/flutter_portal.dart';

const portalLabel = PortalLabel('test');

void main() {
  runApp(const MaterialApp(
    home: Portal(
      labels: [portalLabel],
      child: Example(),
    ),
  ));
}

class Example extends StatefulWidget {

  const Example();

  @override
  State<Example> createState() => _ExampleState();
}

class _ExampleState extends State<Example> {

  bool _visible = true;

  @override
  Widget build(BuildContext context) {
    return OpenContainer(
      closedBuilder: (BuildContext context, VoidCallback openContainer) {
        return Center(
          child: PortalTarget(
            portalCandidateLabels: const [portalLabel],
            visible: _visible,
            portalFollower: const Row(
              mainAxisSize: MainAxisSize.min,
              children: [
                Icon(Icons.arrow_circle_up),
                Text('Tap here'),
              ],
            ),
            anchor: const Aligned(
              target: Alignment.bottomRight,
              follower: Alignment.topCenter,
            ),
            child: ElevatedButton(
              onPressed: () {
                setState(() {
                  _visible = !_visible;
                });
                openContainer();
              },
              child: const Text('Open container'),
            ),
          ),
        );
      },
      openBuilder: (BuildContext context, VoidCallback openContainer) {
        return const Scaffold(body: Center(child: BackButton()));
      },
    );
  }
}

[fzyzcjy]

not throw an error if PortalLinkScope is not found but visibility is false

IIRC flutter_portal has a feature that, if visible becomes false, it may show some animation. (e.g. see

flutter_portal/lib/src/portal_target.dart

Line 387 in 786cd79

class _PortalTargetVisibilityBuilder extends StatefulWidget {

).

However, for your scenario, what about something like: visible ? PortalTarget(..., child: YourButton()) : YourButton(). In other words, when not visible, just directly remove the PortalTarget from the tree.

[jamesncl]

Thanks, that seems to work. I'm still not entirely sure why it's happening as I'm not using a closeDuration on PortalTarget (so I don't think it animates?) and OpenContainer is quite complex. But I think this workaround may be the best solution

[fzyzcjy]

You are welcome!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.