Android data binding is not working with attributes

Question

I\'m trying to use databinding with custom views (a possible usage George Mount showed here).

One can\'t imagine building compound views without <

Answer 1

There is no merge object after inflation, so there is nothing to assign values to with a merge tag. I can't think of any binding tag that will work on merge.

You can assign the tag to the root element and use the BindingAdapter to do what you want.

<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    >

    <data>
        <variable name="data" type="com.example.MyViewModel"/>
    </data>

    <merge
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <ImageView
            app:isGone="@{!data.isViewVisible}"
            android:id="@+id/image_image"
            android:layout_width="60dp"
            android:layout_height="60dp"
            app:imageUrl="@{data.imagePhotoUrl}"/>
         <!-- tons of other views-->
    </merge>
</layout>

If you want to do something with the Binding class itself, you can use the DataBindingUtil to find the object from the View.

@BindingAdapter("isGone")
public static void setGone(View view, boolean isGone) {
    ViewDataBinding binding = DataBindingUtil.findBinding(view);
    //... do what you want with the binding.
}

Answer 2

Actually you can use <merge> tag inside <include> and do data binding.

Ex:

incl_button.xml

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

        <Button android:id="btn"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="Click"
         />

    </merge>
</layout>

fragment_example.xml

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <include
            layout="@layout/incl_button"
            android:id="@+id/layout_btn" />

    </LinearLayout>
</layout>

ExampleFragment.kt

binding.layoutBtn.btn.setOnClickListener{
   //...
}