Example edit text simple form with MvRx and Epoxy

MvrxEpoxyFormExample.kt

// MvRx setup

data class MyState(
    val text: String? = null
)

class MyViewModel : MvRxViewModel() {
    fun setText(newText: String) {
        setState {
            copy(text = newText)
        }
    }
}

class MyFragment : MvRxFragment() {

    val viewModel: MyViewModel by fragmentViewModel()

    fun epoxyController() = simpleController(viewModel) { state ->
        editTextRow {
            id("my edit text")
            inputText()
            inputText(state.text)
            onTextChanged { newText -> viewModel.setText(newText) }
        }
    }
}

// Epoxy view/model setup

@ModelView
class EditTextRow : EditText {
    
    init {
        addTextChangedListener(textChangeWatcher)
    }

    @TextProp
    fun setInputText(text: CharSequence?) {
        if (setTextIfDifferent(text)) {
            // If the text changed then we move the cursor to the end of the new text. This allows us to fill in text programmatically if needed,
            // like a search suggestion, but if the user is typing and the view is rebound we won't lose their cursor position.
            setSelection(length())
        }
    }

    var onTextChanged: ((newText: String) -> Unit)? = null
        @CallbackProp set
    
    private object textChangeWatcher = object : TextWatcher {
        ...
        fun afterTextChanged(text: Editable) {
            onTextChanged?.invoke(text.toString())
        }
    }
}

// Shared utility function

fun TextView.setTextIfDifferent(text: CharSequence?): Boolean {
    if (!isTextDifferent(text, getText())) {
        // Previous text is the same. No op
        return false
    }

    textView.setText(text)

    return true
}

/**
 * @return True if str1 is different from str2.
 *
 * This is adapted from how the Android DataBinding library binds its text views.
 */
fun isTextDifferent(str1: CharSequence?, str2: CharSequence?): Boolean {
    if (str1 === str2) {
        return false
    }
    if (str1 == null || str2 == null) {
        return true
    }
    val length = str1.length
    if (length != str2.length) {
        return true
    }

    if (str1 is Spanned) {
        return str1 != str2
    }

    for (i in 0 until length) {
        if (str1[i] != str2[i]) {
            return true
        }
    }
    return false
}