How to pass data variable to included layout?

Question

Is there a way to pass data variable to included layout?

parent layout

<?xml version="1.0" encoding="utf-8"?>
<layout 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"
    tools:showIn="@layout/fragment_settings">

    <data>

        <variable
            name="viewModel"
            type="......settings.SettingsFragmentViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:animateLayoutChanges="true"
        android:overScrollMode="never"
        android:padding="@dimen/spacing_default">

        <include
            android:id="@+id/main"
            layout="@layout/layout_settings_main" />

    </androidx.constraintlayout.widget.ConstraintLayout>

and want to have viewModel in included layout

<layout 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"
    tools:showIn="@layout/fragment_settings">

    <data>

        <variable
            name="viewModel"
            type="......settings.SettingsFragmentViewModel" />
    </data>

    <merge>
...........

or is it possible only when setting like this:

 binding = FragmentSettingsBinding.inflate(inflater, container, false).apply {
            lifecycleOwner = this@SettingsFragment
            viewModel = [email protected]
            main.viewModel = [email protected]
        }

Alarise

Answer 1

In parent xml inside include tag pass data variable to included layout using bind:viewModel.

<?xml version="1.0" encoding="utf-8"?>
<layout 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"
xmlns:bind="http://schemas.android.com/apk/res-auto"
tools:showIn="@layout/fragment_settings">

<data>

    <variable
        name="viewModel"
        type="......settings.SettingsFragmentViewModel" />
</data>

<androidx.constraintlayout.widget.ConstraintLayout
    android:id="@+id/content"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:animateLayoutChanges="true"
    android:overScrollMode="never"
    android:padding="@dimen/spacing_default">

    <include
        android:id="@+id/main"
        layout="@layout/layout_settings_main"
        bind:viewModel="@{viewModel}" />

</androidx.constraintlayout.widget.ConstraintLayout>

Your included layout will get object instance in viewModel.

For more details check this tutorial

Azotic

What is the difference if I use app:ViewModel or bind:viewModel? – Applicant

Answer 2

Ok so, at the beginning of this article I’ve said that it depends whether it’s possible to pass the variable to a secondary layout or not. The reason for this is the following: Data binding does not support include as a direct child of a merge element. For example, the following layout is not supported:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:bind="http://schemas.android.com/apk/res-auto">
   <data>
       <variable name="user" type="it.communikein.myunimib.User"/>
   </data>
   <merge>
       <include layout="@layout/name"
           bind:user="@{user}"/>
       <include layout="@layout/contact"
           bind:user="@{user}"/>
   </merge>
</layout>

Resemblance

and what is supported? – Alarise

The <data> tag includes a <variable> tag that has the same name that we used in the main layout to pass the data to the secondary layout: secondary user. Also, it has the same type of variable declared in the main layout. – Resemblance

Answer 3

Open build.grade and add dataBinding { enabled = true } in block android{ // ...}

Dora

databinding is already working. Please read the question first – Alarise

I thought databinding isn't already working because don't see your config in file build.grade. Sorry :( – Dora