I am using the new AndroidX navigation framework.
I have a few fragments all linked in a navigation chain.
FragmentA --> FragmentB --> FragmentC
FragmentC has a Cancel button that should send me up all the way back to FragmentA.
Should I do the following:
on FragmentC call the method:
Navigation.findNavController(view).navigateUp();
then on FragmentB listen to some callback and using some passed parameter or argument trigger another navigateUp() function from FragmentB
or is there some method that will do the equivalent of navigateUpTwice()
What I ended up doing was
Navigation.findNavController(view).popBackStack(R.id.fragmant_a,false)
In your navigation.xml file under the action that you have created to navigate to starting fragment (FragmentA in your case) add the following
<action
....
app:popUpTo="#id/fragmentA"
app:popUpToInclusive="false"/>
This will pop up all the fragments until FragmentA and will exclude FragmentA since popUpToInclusive is set to false.
Edit:
The full form of your action under FragmentC tag of your navigation.xml file will be something similar to this:
<fragment
android:id="#+id/FragmentC"
android:name="com.yourdomain.FragmentC"
android:label="FragmentC">
<action
android:id="#+id/action_fragmentC_to_fragmentA"
app:destination="#id/fragmentA"
app:popUpTo="#id/fragmentA"
app:popUpToInclusive="false"/>
</fragment>
Try with this, it works for me.
findNavController().navigateUp()
findNavController().navigateUp()
You can set pop To FragmentA in your action from FragmentB --> FragmentC and when then you press back it goes to Fragment A instead of Fragment B
So I found myself in a situation where I had to navigateUp() twice, but with a twist: I could reach the view through several paths. Think of it like this:
Fragment A --> Fragment C --> Fragment D
Fragment B --> Fragment C --> Fragment D
In a normal situation, using the popTo xml attribute or the popBackStack() method would work. However it is unusable here. Fortunately, what you can do is:
val navController = NavHostFragment.findNavController(this)
navController.navigateUp()
navController.navigateUp
As other people have pointed out, this is absolutely not optimised performance-wise. In any situation where you can reach Fragment D through a single path, use popTo instead.
Related
I've 2 fragments, A & B
with action:
<action
android:id="#+id/action_a_to_b"
app:destination="#id/b"
app:enterAnim="#android:anim/fade_in"
app:exitAnim="#android:anim/fade_out"
app:popEnterAnim="#android:anim/fade_in"
app:popExitAnim="#android:anim/fade_out"
app:popUpTo="#id/a"/>
after I move from a to b and pressing back,
and then try again to open b from a, the app crashes and the problem is that the navigation graph current destination remains fragment b instead of changing to a.
Update:
if fragment B inherit from Fragment class, it doesn't happen
if fragment B inherit from BottomSheetDialogFragment it does happen
any idea why?
Thanks.
The problem was that i used the tag instead of in the navigation graph...
I have a question. I'm using nav component for navigation. For example i have fragment A, B and C and bottomNavigation. I'm using
binding.bottomNavigation.setupWithNavController(navController)
For multiple backstack. But here is situation: Main frag is A. I'm moving to fragment B or C. I have buttons on fragments B and C which should lead me to fragment A with putted arguments in it so i'm using just:
findNavController().navigate(fragmentBDirections.fromFragmentBToFragmentA(argument))
But here is a problem. I'm recreating fragment A after this but i'm already have this fragment in backstack. So is it possible to find A in backstack and navigate to it without recreating? Is it possible to save backstack after that?
Your problem seems like an ideal case to use a sharedViewModel
Your button in B or C should pop and fallback to A after updating a property in the viewModel. On leaving, the viewModel is not destroyed because it is bound to the activity and is available for Fragment A.
Bonus is using LiveData so that the change is observed and updated automatically
I think SavedStateHandle might be helpful.
<Navigation>
<fragment
android:id="#+id/BFragment"
android:name="com.packageName.app.BFragment"
android:label="fragment_b"
tools:layout="#layout/fragment_b" >
<action
android:id="#+id/action_BFragment_pop_including_AFragment"
app:popUpTo="#id/AFragment"
app:launchSingleTop="true" />
</Navigation>
<Navigation>
<fragment
android:id="#+id/CFragment"
android:name="com.packageName.app.CFragment"
android:label="fragment_c"
tools:layout="#layout/fragment_c" >
<action
android:id="#+id/action_CFragment_pop_including_AFragment"
app:popUpTo="#id/AFragment"
app:launchSingleTop="true" />
</Navigation>
try it . it's my solution
I am using Navigation Component in my project and :
I need to open a fragment in a different level of hierarchy, so that the back stack is created properly too
in my nav_graph.xml there is a hierarchy like this:
HomeFragment -> CollocationFragment -> ChapterFragment --[selfNavigate]--> ChapterFragment -> PlayerFragment
as you see one of my fragments navigates to itself and send an arguments each time like this:
<fragment
android:id="#+id/ChapterFragment ">
<action
android:id="#+id/action_chapterFragment_self"
app:destination="#id/ChapterFragment" />
<argument
android:name="chapterID"
app:argType="Long" />
</fragment>
in a nutshell, I need to open PlayerFragment from HomeFragment with an appropriate backstack (the hierarchy mentioned above) .
HomeFragment ---[my back stack]---> PlayerFragment
I know that it seems NavDeepLinkBuilder creates the backstack itself but I have no idea how to create a custom backstack by using Navigation component for my fragments in this case.
eventually I find a way...it's kind of a workaround but it works like a charm:
so, just call navigate function in your desire order to make the hierarchy backstack:
fun openPlayerFromHome(){
findNavController.navigate(R.id.HomeFragment)
findNavController.navigate(R.id.CollocationFragment)
findNavController.navigate(R.id.ChapterFragment,bundleOf("chapterID",id))
findNavController.navigate(R.id.PlayerFragment)
}
I have 4 Fragments , A, B,C.Fragment A will be the main Fragment, I will be navigating from fragment A to Fragment B then Fragment B return with a result to fragment A. Then I will navigate To fragment C from fragment A, and fragment c will do some operations and return a result to fragment A. Each time the fragment A will show and keep the result returned from each fragment
The navigation between fragment A to the other fragment is implemented using this code
val bundle = Bundle()
bundle.putBoolean("data", true)
findNavController().navigate(R.id.myAction, toVoicePassphraseRecognitionbundle)
My problem her is that to return to fragment A, i also use findNavController().navigate()but doing so will create a new fragment that will be added to the stack, so my question is how can i navigate back from fragment B to A, or C to A while keeping the view state as it is without creating a new Fragment A.
The problem is, you are setting Fragment A as destination in your action,
what it does is, it creates a new instance of the Fragment.
What you really want is to go back to, not go to.
So what we we do to go back, we pop our back stack.
<fragment
android:id="#+id/fragmentC"
android:name="com.sample.project.FragmentC"
android:label="FragmentC">
<action
android:id="#+id/navigate_C_to_A"
app:popUpTo="#+id/fragmentA"
app:popUpToInclusive="false" />
</fragment>
popUpTo is where you want to land
popUpToInclusive means do you want this fragment to pop from stack too?
And let say your flow is like A->B->C->A
But Fragment A is unknown, or B and C are the part of flow that can be used at many places, so the A will not be A every time.
In that case :
<fragment
android:id="#+id/fragmentC"
android:name="com.sample.project.FragmentC"
android:label="FragmentC">
<action
android:id="#+id/navigate_C_to_before_B"
app:popUpTo="#+id/fragmentB"
app:popUpToInclusive="true" />
</fragment>
popUpToInclusive is the key here
My flow of fragment is like this
Main -> A -> B -> C ->A
In fragment c, it has a submit button which will return to A.
When I press back button in A, I want it back to Main. But it return to fragment c instead.
In fragment C, I use this
findNavController().navigate(R.id.action_c_to_a)
nav_graph.xml
<fragment
android:id="#+id/fragmentC"
android:name="xxx"
android:label="xxx">
<action
app:launchSingleTop="true"
app:popUpTo="#+id/fragmentA"
app:popUpToInclusive="true"
android:id="#+id/action_c_to_a"
app:destination="#id/fragmentA" />
</fragment>
Why not pop up to fragment A? You could just call findNavController().popBackStack(R.id.fragmentA, false) instead of navigating with an action.
try to look at my complete solution with removing/killing fragment from backstack.
Navigation Component set transition animation programmatically
You can override the back button behavior to do this.
Provide custom back navigation
The idea is to set a app:popUpTo without setting app:destination. Indeed, setting a app:destination will create a fragment and add it to the backstack which is not what you want.
To you can just remove :
app:destination="#id/fragmentA"
If you have this :
app:popUpTo="#+id/fragmentA"
And it will really pop the backstack until fragmentA