BottomNavigationView - Multiple start destinations on back stack [253256629]

Fixed

Bug

Status Update

No update yet.

Description

po...@gmail.com

created issue #1

Oct 12, 2022 05:54PM

Component used: Navigation / NavigationUI Version used: 2.5.2 Devices/Android versions reproduced on: OnePlus 8T / Android 12

I'm using a menu resource file which is bound to a BottomNavigationView. Also I'm setting up the navigation like so NavigationUI.setupWithNavController(bottomNavigationView, navController, false) which means I'm using the experimental version of this API.

I don't want the state of each menu item to be saved since I want to come back to the respective start destination if a BottomNavigationView item gets reselected. So regardless of how deep I got in a navigation graph a reselection of the same item takes you back to the start destination.

I'm using a navGraph which consists of several nested navGraphs like so:

<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/navigation"
    app:startDestination="@id/destination_one">

    <include app:graph="@navigation/one_navigation" />

    <include app:graph="@navigation/two_navigation" />

    <include app:graph="@navigation/three_navigation" />

    <include app:graph="@navigation/four_navigation" />
</navigation>

The one_navigation could look like this:

<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/destination_one"
    app:startDestination="@id/destination_fragment_one">

    <fragment
        android:id="@+id/destination_fragment_one"
        android:name="com.example.OneFragment"
        android:label="@string/bottom_navigation_one"
        tools:layout="@layout/fragment_one">
    </fragment>
</navigation>

It works pretty good so far, the point is when I click the first BottomNavigationView's menu item N times I got the destination N+1 times on my back stack. If I wanted to leave the app by triggering the system's back navigation I'd have to do it N+1 times.

So I actually expect the startDestination to only exist once on the back stack regardless of how often I click the respective menu item setup with the above mentioned API.

Comments

il...@google.com <il...@google.com> #2Oct 12, 2022 06:07PM

Can you include a sample project that reproduces your issue?

Note that if you want to just return to your main graph (which I assume launched your login_nav_graph), you would want to leave out the app:destination="@id/main_nav_graph" line entirely as that will create a second instance of your main_nav_graph.

po...@gmail.com <po...@gmail.com> #3Oct 12, 2022 06:35PM

Thank you! While working on a minimal repro and keeping your comment in mind, I solved my problem.

My problem was partly that I had an app:destination in my pop action, but also that the action leading to login_nav_graph was popping:

<action
    android:id="@+id/logout"
    app:destination="@id/login_nav_graph"
    app:popUpTo="@id/main_nav_graph"
    app:popUpToInclusive="true" />

Here is a working sample of what I wanted to achieve:

main_nav_graph.xml

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_nav_graph"
    app:startDestination="@id/mainFragment">

    <fragment
        android:id="@+id/mainFragment"
        android:name="app.reitan.navigationrepro.MainFragment"
        android:label="fragment_main"
        tools:layout="@layout/fragment_main">
        <action
            android:id="@+id/to_login_nav_graph"
            app:destination="@id/login_nav_graph"/>
    </fragment>

    <include app:graph="@navigation/login_nav_graph" />
</navigation>

login_nav_graph.xml

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/login_nav_graph"
    app:startDestination="@id/loginFragment">

    <fragment
        android:id="@+id/loginFragment"
        android:name="app.reitan.navigationrepro.LoginFragment"
        android:label="fragment_login"
        tools:layout="@layout/fragment_login">
        <action
            android:id="@+id/pop_login_nav_graph"
            app:popUpTo="@id/main_nav_graph"
            app:popUpToInclusive="true" />
    </fragment>
</navigation>

il...@google.com <il...@google.com> #4Oct 12, 2022 06:57PM

Even though the error was probably in my code, this is still a change of behavior, as this used to work fine in 2.3.0. Just so you know :)

po...@gmail.com <po...@gmail.com> #5Oct 13, 2022 05:32PM

Trying to recreate this issue in a sample project as well, but I am seeing the same thing. However I am navigating by id instead of action.

il...@google.com <il...@google.com> Oct 18, 2022 08:52PM

Assigned to jb...@google.com.

jb...@google.com <jb...@google.com> #6Oct 21, 2022 12:14AM

Reassigned to cl...@google.com.

Have the same issue with Navigation Component v2.4.0-alpha02, and no issue with 2.3.0
Here is the sample project that reproduces the issue:

https://github.com/eugene-kirzhanov/nav-test

po...@gmail.com <po...@gmail.com> #7Oct 21, 2022 08:02AM

While the project in comment#6 is absolutely the wrong way to do conditional navigation (instead, you should follow the guide for login, it does reproduce the issue reliably enough for us to pinpoint what the problem is.

cl...@google.com <cl...@google.com> Nov 8, 2022 01:25AM

Accepted by cl...@google.com.

ap...@google.com <ap...@google.com> #8Dec 1, 2022 09:33PM

Project: platform/frameworks/support
Branch: androidx-main

commit 91744799f42b2b5bc42c727a17cd3618eb232c01
Author: Ian Lake <ilake@google.com>
Date: Tue Jun 08 19:02:25 2021

Ensure that NavGraphNavigator stack order remains correct

When popping the root graph, the root graph
needs to be added to the front of the
hierarchy to ensure that the
navigatorBackStack for the NavGraphNavigator
is rebuilt in the correct order.

This ensures that future popBackStack() calls
will find that the NavController's back stack
ordering matches the NavigatorState of the
NavGraphNavigator, avoiding an
IllegalStateException.

Test: new NavControllerTest test passes
BUG: 190265699
Relnote: "Fixed an IllegalStateException when
calling popBackStack() after previously popping
the root graph of the NavController."

Change-Id: I2a330acdd339aece36455aa0da37d0609767552c

M navigation/navigation-runtime/src/androidTest/java/androidx/navigation/NavControllerTest.kt
M navigation/navigation-runtime/src/androidTest/res/navigation/nav_multiple_navigation.xml
M navigation/navigation-runtime/src/main/java/androidx/navigation/NavController.kt

https://android-review.googlesource.com/1731130

ap...@google.com <ap...@google.com> #9Dec 14, 2022 07:34PM

We've fixed the underlying issue (related to popping the root graph, then navigating to another nested graph) internally and it will be available in Navigation 2.4.0-alpha03.

cl...@google.com <cl...@google.com> #10Dec 14, 2022 07:39PM

Marked as fixed.

This has been fixed internally and will be available in Navigation 2.6.0-alpha05

pr...@google.com <pr...@google.com> #11Feb 8, 2023 06:22PM

The following release(s) address this bug.It is possible this bug has only been partially addressed:

androidx.navigation:navigation-common:2.6.0-alpha05
androidx.navigation:navigation-runtime:2.6.0-alpha05