Please drive Fragment Lifecycle methods with LifecycleObserver [127528777]

Assigned

Feature Request

Status Update

No update yet.

Description

he...@gmail.com

created issue #1

Mar 6, 2019 05:57AM

Component used: Fragment
Version used:
Devices/Android versions reproduced on:

Driving Fragment Lifecycle methods with methods from LifecycleObserver would make the connection between their behavior more obvious, and would fix inconsistency of calling order between Fragment.onStop and Fragment.onSaveInstanceState in Android <28 vs Android 28+

Comments

il...@google.com <il...@google.com> Mar 6, 2019 06:11PM

Assigned to il...@google.com.

ap...@google.com <ap...@google.com> #2Apr 19, 2019 11:05PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 85c1de7395f07e3256a50706d4f619e654624250
Author: Ian Lake <ilake@google.com>
Date: Fri Apr 19 13:54:21 2019

Ensure Fragment OnBackPressedCallbacks take priority

As FragmentController is not yet driven by a
LifecycleObserver (

b/127528777

), LifecycleObservers on
Fragments are not necessarily nested within
LifecycleObservers registered at the Activity level.
This can lead to cases where a Fragment is started
before the Activity's Lifecycle is started.

In the case of FragmentManager's usage of Lifecycle to
add OnBackPressedCallbacks, that nesting is critical
to ensure the ordering of callbacks. By creating a
host level Lifecycle that is exactly nested outside
the callbacks to FragmentController, we can ensure
the proper nesting in callbacks.

Test: added test passes
Change-Id: I958d2389c90dcd9d157c6c3d30dffb689ed40c62

M fragment/src/androidTest/AndroidManifest.xml
M fragment/src/androidTest/java/androidx/fragment/app/OnBackPressedCallbackTest.kt
M fragment/src/main/java/androidx/fragment/app/FragmentActivity.java

https://android-review.googlesource.com/948209

https://goto.google.com/android-sha1/85c1de7395f07e3256a50706d4f619e654624250

il...@google.com <il...@google.com> #3May 23, 2019 11:02PM

FWIW, I think this is a fantastic idea and would go a long way in bringing sanity to the world of lifecycle. As it would change the ordering between Activity lifecycle methods and Fragment lifecycle methods, this will almost certainly be an opt-in flag set at the FragmentActivity level.

ch...@instacart.com <ch...@instacart.com> #4Dec 4, 2019 05:53PM

It's worth noting, that I actually expected the Activity to fire Lifecycle.Event.ON_CREATE from `Activity.onCreate` which is what the fragmentLifecycleRegistry does.

Not sure how this would be exposed, but driving Activity.getLifecycle events from the ReportFragment which is actually a different lifecycle to that Activity is very odd.

Not sure on the API, but a getActivityLifecycle and getFragmentLifecycle would be nice in this situation, as I actually want my lifecycle events to fire IN onCreate not in onStart.

ne...@gmail.com <ne...@gmail.com> #5Apr 6, 2020 08:30AM

Hi, any news?

sk...@gmail.com <sk...@gmail.com> #6Feb 5, 2022 08:26AM

Hello Ian,
any chance to fix this by just returning the already existing mFragmentLifecycleRegistry in getLifecycle() overload?
This really caused us back-press handling issues as mentioned in my b/217740645 duplicate.
Currently I'm workarounding this with a reflection to register the callback with mFragmentLifecycleRegistry lifecycle.
Thank you.

ju...@veepee.com <ju...@veepee.com> #7Jan 13, 2024 05:18PM

Is this ever going to be implemented? My team is facing issues related to this as well... Be it with registering OnBackPressed on orientation changes or driving the ViewLifecycle in some cases...