Kotlin 2-way binding custom view

Question

I have 1 custom view that extends ConstraintLayout and contains 1 EditText and 2 TextViews

On my custom view i define this attr (and others) :

<attr name="Text" format="string" />

and i use it like :

app:Text="@={login.email}"

Inside my custom view i define :

  companion object {
    @JvmStatic @BindingAdapter("Text")
    fun setText(nMe : View, nText: String) {
        nMe.nInput.setText(nText)
    }
    @InverseBindingAdapter(attribute = "Text")
    fun getText(nMe : View) : String {
      return  nMe.nInput.text.toString()
    }

witch works fine in one-way binding

app:Text="@{login.email}"

But when i try to use it in 2-way binding i get erros pointing to ActivityLoginBinding.java java.lang.String callbackArg_0 = mBindingComponent.null.getText(mEmail);

What to do to get 2-way binding?

L.E : After some research i end up with this :

@InverseBindingMethods(InverseBindingMethod(type = 
CustomInput::class,attribute = "bind:Text",event = 
"bind:textAttrChanged",method = "bind:getText"))
class CustomEditTextBinder {
companion object {
    @JvmStatic
    @BindingAdapter(value = ["textAttrChanged"])
    fun setListener(editText: CustomInput, listener: InverseBindingListener?) {
        if (listener != null) {
            editText.nInput.addTextChangedListener(object : TextWatcher {
                override fun beforeTextChanged(charSequence: CharSequence, i: Int, i1: Int, i2: Int) {

                }

                override fun onTextChanged(charSequence: CharSequence, i: Int, i1: Int, i2: Int) {

                }

                override fun afterTextChanged(editable: Editable) {
                    listener.onChange()
                }
            })
        }
    }

    @JvmStatic
    @InverseBindingAdapter(attribute = "Text")
    fun getText(nMe: CustomInput): String {
        return nMe.nInput.text.toString()
    }

    @JvmStatic
    @BindingAdapter("Text")
    fun setText(editText: CustomInput, text: String?) {
        text?.let {
            if (it != editText.nInput.text.toString()) {
                editText.nInput.setText(it)
            }
        }
    }
}

}

But right now i get : Could not find event TextAttrChanged

Did you tried to use @InverseBindingMethods(InverseBindingMethod(event = "android:textAttrChanged"))... in your InverseBindingMethod — Narek Hayrapetyan, Aug 30 '18 at 08:10

Sam Chen · Answer 1 · 2020-10-31T03:27:14.507

I think all you need is event = "android:textAttrChanged".

This works for me (set text to empty String if it is 0):

object DataBindingUtil {
    @BindingAdapter("emptyIfZeroText")
    @JvmStatic
    fun setText(editText: EditText, text: String?) {
        if (text == "0" || text == "0.0") editText.setText("") else editText.setText(text)
    }

    @InverseBindingAdapter(attribute = "emptyIfZeroText", event = "android:textAttrChanged")
    @JvmStatic
    fun getText(editText: EditText) = editText.text.toString()
}

Kotlin 2-way binding custom view

1 Answers1