Provide a way to handle navigating back and forth between NavHostFragments embedded within other NavHostFragments (or if it's already available, document how to do) [120690961]

Fixed

Feature Request

Status Update

No update yet.

Description

je...@23andme.com

created issue #1

Dec 9, 2018 03:07AM

Component used: Navigation
Version used: 1.0.0-alpha08
Devices/Android versions reproduced on:

Assuming:
- Main Activity has a NavHostFragment, which navigates between Fragment A & Fragment B
- Main activity handles going back with onSupportNavigateUp
- Fragment B has it's own NavHostFragment, which navigated between InnerFragmentB1 & InnerFragmentB2
- Parent NavHostFragment navigates from A -> B (which starts with B1)
- Sub NavHostFragment navigates from B1 -> B2
- Press up: Sub NavHostFragment returns to B1
- Press up: Parent NavHostFragment returns from B to A

What's the proper way of handling these types of situations where we'd like the back button to handle backing out of Inner Fragments first and then Outer Fragments after?

Details here:

https://stackoverflow.com/q/53688934/1229936
Sample Code:

https://github.com/jeffreyfhow/NestedNavFragmentsTest

Comments

so...@gmail.com <so...@gmail.com> #2Dec 9, 2018 07:33AM

What about Enums? Enum is a type-safe way to pass navigation arguments.
Will Enums be covered in this issue as part of Serializable or will have own handled separately?
Because for enum you can provide a reasonable default value but for Parcelable or Serializable only @null

il...@google.com <il...@google.com> #3Dec 10, 2018 05:58PM

Please add support for Serializable objects so Enums can be used.

il...@google.com <il...@google.com> Dec 10, 2018 09:55PM

Accepted by il...@google.com.

il...@google.com <il...@google.com> #4Dec 14, 2018 12:05AM

Marked as fixed.

Support of Serializable objects is not enough for enums, you definitely need also the support of default values.

ka...@gmail.com <ka...@gmail.com> #5Dec 27, 2018 05:06PM

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

commit 6f59e3d74d0da5a4bf79c8480f56964e3af47f1c
Author: Wojtek Kaliciński <wkal@google.com>
Date: Mon Jul 23 20:17:19 2018

Support more types for args

Provides support for Serializable, enums,
as well as arrays of primitive types and Parcelables
in Navigation arguments.

Only enums support default values other than @null,
in the form of the enum literal (without class name),
e.g. app:defaultValue="READ"

Test: unit tests updated
BUG: 111487504
BUG: 111316353
Change-Id: I7e5abbc8ed0950bfdef292342dbe1fb34a5c4b17

M navigation/runtime/src/androidTest/java/androidx/navigation/NavInflaterTest.kt
A navigation/runtime/src/androidTest/java/androidx/navigation/test/TestEnum.java
M navigation/runtime/src/androidTest/res/navigation/nav_default_arguments.xml
M navigation/runtime/src/main/java/androidx/navigation/NavInflater.java
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavParser.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavParserErrors.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/NavWriter.kt
M navigation/safe-args-generator/src/main/kotlin/androidx/navigation/safe/args/generator/Types.kt
M navigation/safe-args-generator/src/tests/kotlin/androidx/navigation/safe/args/generator/NavParserTest.kt
M navigation/safe-args-generator/src/tests/kotlin/androidx/navigation/safe/args/generator/NavWriterTest.kt
M navigation/safe-args-generator/src/tests/test-data/expected/nav_writer_test/MainFragmentArgs.java
M navigation/safe-args-generator/src/tests/test-data/expected/nav_writer_test/Next.java
M navigation/safe-args-generator/src/tests/test-data/naive_test.xml

https://android-review.googlesource.com/720246

https://goto.google.com/android-sha1/6f59e3d74d0da5a4bf79c8480f56964e3af47f1c

Issue 120690961