How to pass arguments to a fragment using bottom navigation view and Android Navigation component?

Question

Is it possible to pass and access arguments in a fragment using a bottom navigation view and the Navigation component?

I'm using a one activity with many fragments approach where my top level fragment requires an argument(Usually done via the newInstance generated method). I've had a look at the Navigation component developer guide and the codelab but it only mentions using safeargs and adding argument tags in the destinations and actions.

Here's my navigation graph:

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

    <fragment android:id="@+id/homeFragment"
          android:name="uk.co.homeready.homeready.HomeFragment"
          android:label="fragment_home"
          tools:layout="@layout/fragment_home">
          <!--Do I create an argument block here?-->
    </fragment>

    <fragment android:id="@+id/calculatorFragment"
          android:name="uk.co.homeready.homeready.CalculatorFragment"
          android:label="fragment_calculator"
          tools:layout="@layout/fragment_calculator"/>

    <fragment android:id="@+id/resourcesFragment"
          android:name="uk.co.homeready.homeready.ResourcesFragment"
          android:label="fragment_resources"
          tools:layout="@layout/fragment_resources"/>

</navigation>

Bottom Navigation View menu:

<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/homeFragment"
        android:icon="@drawable/ic_home_black_24dp"
        android:title="@string/title_home"/>

    <item
        android:id="@+id/calculatorFragment"
        android:icon="@drawable/ic_baseline_attach_money_24px"
        android:title="@string/title_calculator"/>

    <item
        android:id="@+id/resourcesFragment"
        android:icon="@drawable/ic_baseline_library_books_24px"
        android:title="@string/title_resources"/>

</menu>

MainActivity:

override fun onCreate(savedInstanceState: Bundle?) {
        ...
        val navController = Navigation.findNavController(this, 
        R.id.nav_host_fragment)
        bottom_navigation.setupWithNavController(navController)
        ....
}

activity_main.xml

<android.support.constraint.ConstraintLayout>
    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        app:layout_constraintBottom_toTopOf="@id/bottom_navigation"
        app:defaultNavHost="true"
        app:navGraph="@navigation/nav_graph"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_navigation"
        app:menu="@menu/bottom_navigation"/>

</android.support.constraint.ConstraintLayout>

HomeFragment

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    val argument = //TODO access argument here
    ...
}

So you want your `homeFragment` to be started with some default set of arguments when you tap on it from the bottom nav? Are you reusing the `homeFragment` somewhere else with different arguments then or are they always just fixed values? — ianhanniballake, Jan 07 '19 at 23:10
Yes for my usecase I would like to pass some default set arguments when you tap the bottom nav. I would also possibly reuse homeFragment somewhere else too. — skon, Jan 08 '19 at 10:55

score 31 · Accepted Answer · edited Jun 23 '20 at 15:14

31

If I understood you correctly, you want to pass arguments to destinations that is tied to menu items. Try to use 'OnDestinationChangedListener' inside your activity onCreate method, something like this:

navController.addOnDestinationChangedListener { controller, destination, arguments ->
        when(destination.id) {
            R.id.homeFragment -> {
                val argument = NavArgument.Builder().setDefaultValue(6).build()
                destination.addArgument("Argument", argument)
            }
        }
    }

Update:

If you want that your start destination will receive default arguments the implementation should be different. First, remove 'app:navGraph="@navigation/nav_graph"' from your 'NavHostFragment' xml tag.

Then, inside your activity onCreate you need to inflate the graph:

 val navInflater = navController.navInflater
 val graph = navInflater.inflate(R.navigation.nav_graph)

Then add your arguments to graph(this arguments will be attached to start destination)

val navArgument1=NavArgument.Builder().setDefaultValue(1).build()           
val navArgument2=NavArgument.Builder().setDefaultValue("Hello").build()
graph.addArgument("Key1",navArgument1)
graph.addArgument("Key2",navArgument2)

Then attach the graph to NavController:

navController.graph=graph

Now your first destination should receive the attached arguments.

edited Jun 23 '20 at 15:14

Aykhan Hagverdili

28,141
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answered Jan 08 '19 at 06:55

Alex

9,102
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1

Thanks for the answer Alex. I'm retrieving the the argument in the HomeFragment via `val argument = arguments?.getString("Argument")` However on app start up `argument` is null in HomeFragment even though I can see that the listener is being called and the argument is being created in the main activity. I have to tap on another item in the bottom nav and then tap and navigate back to HomeFragment in order for `argument` to return something – skon Jan 08 '19 at 11:09
2

The reason why the `OnDestinationChangedListener` only works the second time is because that is called after the `navigate()` call is done and the arguments are set for the first Fragment. Adding the `` to the graph is the exact equivalent to manually creating a `NavArgument` at runtime and is the recommended approach. – ianhanniballake Jan 08 '19 at 17:20
3

I tried first approach, OnDestinationChangedListener is not working on very first time. – Shrikant May 29 '19 at 08:18
@ianhanniballake I'm having the same problem where `OnDestinationChangedListener` doesn't work the first time. I added my argument to the destination through xml aswell, but it still didn't work. Any ideas as to why? – Khodor Jan 26 '20 at 11:28

score 7 · Answer 2 · answered Jan 08 '19 at 17:18

7

The correct way to do this is indeed with an <argument> block on your destination.

<fragment android:id="@+id/homeFragment"
      android:name="uk.co.homeready.homeready.HomeFragment"
      android:label="fragment_home"
      tools:layout="@layout/fragment_home">
      <argument
          android:name="Argument"
          android:defaultValue="value"
          />
</fragment>

This will automatically populate the arguments of the Fragment with the default value without any additional code needed. As of Navigation 1.0.0-alpha09, this is true whether you use the Safe Args Gradle Plugin or not.

answered Jan 08 '19 at 17:18

ianhanniballake

191,609
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How can i receive these arguments in destination fragment? – Nauman Ash Mar 24 '19 at 10:51
1

@NaumanAsh - how you receive the arguments, be it via Safe Args or not, is covered in [the documentation](https://developer.android.com/guide/navigation/navigation-pass-data#Safe-args) – ianhanniballake Mar 24 '19 at 13:27
@ianhanniballake Can we change the argument value programmatically when an item is tapped from the `bottomNavView`? – Zain Nov 08 '21 at 19:59
Where are these arguments populated from? The main activity? – Mattwmaster58 Apr 05 '22 at 02:22
@Mattwmaster58 - the `android:defaultValue` means that this argument is always added, no matter how you `navigate` to that fragment. – ianhanniballake Apr 05 '22 at 02:39

score 3 · Answer 3 · answered Jan 02 '20 at 12:42

Default values was not usable for me, because I have dynamic menu items that could have multiple of the same destination with different arguments. (changed from server)

Implement BottomNavigationView.OnNavigationItemSelectedListener:

override fun onNavigationItemSelected(item: MenuItem): Boolean {
    val fragmentId = item.itemId
    val arguments = argumentsByFragmentId[fragmentId] // custom mutableMapOf<Int, Bundle?>() with arguments
    navController().navigate(fragmentId, arguments)
    return true
}

To use that you will takeover the navigation, by replacing the listener. The order of calls here are important:

bottomNavigationView.setupWithNavController(navController)
bottomNavigationView.setOnNavigationItemSelectedListener(this)

How to pass arguments to a fragment using bottom navigation view and Android Navigation component?

3 Answers3

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