Flutter Camera Plugin CameraController Not Initialising - flutter

Question

I'm trying to use the Flutter camera plugin to display a live video of a user's camera.
class Page extends StatefulWidget {
const Page({Key? key}) : super(key: key);
#override
_DashboardState createState() => _DashboardState();
}
class _DashboardState extends State<Dashboard> {
late List<CameraDescription> cameras;
late CameraController _controller;
Future<void> _setupCameras() async {
try {
cameras = await availableCameras();
_controller =
new CameraController(cameras[0], ResolutionPreset.medium);
await _controller.initialize();
}catch(e){
throw e;
}
}
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: _setupCameras(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
return AspectRatio(
aspectRatio: _controller.value.aspectRatio,
child: CameraPreview(_controller)
);
}
);
}
}
I keep receiving the error:
type 'Null' is not a subtype of type 'CameraController' of 'function result'
I have tried null checking the cameras and _controller variables with List<CameraDescription>? cameras;, CameraController? _controller instead of using late, but with that I get the error: Null check operator used on a null value.
The code provided on the camera plugin page appears to be outdated.
Any suggestions? Thanks

Answer 1

I believe this may be because in the FutureBuilder you create the future by calling _setupCameras() within the build function. The FutureBuilder documentation explicitly states that the future must be initialized outside of the build function:
If the future is created at the same time as the FutureBuilder, then every time the FutureBuilder's parent is rebuilt, the asynchronous task will be restarted.
You can fix this by adding a field setupDone = _setupCameras() to the initState method of your widget, and then referring to that field in your FutureBuilder