Hey guys, very new to flutter and have been learning in order to start making pull requests on Github. However its been a while since ive used a non-R programming language so I might be a bit rusty with some concepts.

For reference, the repo i want to help out is Thunder

What im trying to do is cause a page to scroll to the top, when the user presses the bottom navigation bar button for that page.

So it goes PageView, CommunityPage, then PostCardList, which is a class containing a ListView showing the cards and whatever else.

I get that I need to pass one of the scrollControllers up to the main PageView level, and then use the BottomNavigationBar onTap (index) function to call an animateTo on it. But i dont know where, or how i pass the scrollcontroller up a level. When i know how, do i just pass it from the PostCardList class, to the CommunityPage class, to the PageView-level class? Or is there some better way??

Sorry for such a low level question but ive been learning this for like 2 or 3 days and have no experience whatsoever hahaha

Thanks!

  • @[email protected]
    2•1 year ago

    You could pass it up a level by having the ScrollController be a class property obtained thru the constructor, which the parent would then provide when calling the widget.

    This gets unwieldy fast. That’s where the state management solutions come in. From the pubspec.yaml, it seems Thunder uses Bloc for that. Look at the docs.

  • Problematic ConsumerM
    2•1 year ago

    I have implemented something like this before, if I remember correctly I’ve done it with riverpod’s ref.listen.

    Basically, each tab (of PageView) has its own ScrollController and we don’t care about exact implementation on each tab and simply notify that tab to scroll up. You can create a simple StateProvider<int>, then on click of BottomNavigationBar set the provider to its index. Then on each tab, use ref.listen(theprovider.select(value) => value == tabindex) etc.

    There are other ways, of course, but this one gets the job done.

    • 🅱🅴🅿🅿🅸OP
      1•1 year ago

      Thanks for the reply! Bit it might be a bit advanced for me at this stage… Do you have any youtube vids or other resources that might help me out with those concepts?