Android Data Binding does not work with Kotlin's class delegation

Question

My ViewModel:

class MyVM(
        app: Application,
        private val observableImpl: BaseObservable,
        /* other colaborators*/
) : AndroidViewModel(app), Observable by observableImpl {

    var currencyCode: String by Delegates.observable("") { _, _, newValue ->

        /* business logic methods */

        notifyPropertyChanged(BR.currencyCode)
    }
        @Bindable get

}

My 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">

    <data>

        <variable
            name="vm"
            type="path.to.MyVM" />

    </data>

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{vm.currencyCode}"
            app:layout_constraintEnd_toEndOf="parent" />

    </android.support.constraint.ConstraintLayout>
</layout>

When currencyCode gets updated in the data model, TextView does not change the text automatically.

I have tried to get rid of inheriting from AndroidViewModel and defined MyVM as follows:

class MyVM(/* other colaborators*/) : BaseObservable() {
}

And it worked. The problem is that I cannot throw away the inheritance from AndroidViewModel in my production code.

There is a workaround though:

val currencyCode = ObservableField<String>()

But I am not comfortable with using ObservableFields in my ViewModel. Do you have any suggestions?

Android Data Binding does not work with Kotlin's class delegation

0 Answers0