TornadoFX how to add validation while editing TableView - kotlin

Question

Consider folowing example:
class Item(name: String, number: Int) {
val nameProperty = SimpleStringProperty(name)
var name by nameProperty
val numberProperty by lazy { SimpleIntegerProperty(number) }
var number by numberProperty
}
class MainView : View("Example") {
val items = listOf(Item("One", 1), Item("Two", 2)).observable()
override val root = vbox {
tableview(items) {
column("Name", Item::nameProperty).makeEditable()
column("Number", Item::numberProperty).makeEditable(NumberStringConverter())
enableCellEditing()
}
}
}
How can I add a validator while editing cells? Is the only way to do that is to add rowExpander with some textfield and try to validate a model there?

Answer 1

You can either implement your own cellfactory and return a cell that shows a textfield bound to a ViewModel when in edit mode and an label if not. Alternatively, if you're fine with always displaying a textfield, you can use cellFormat and bind the current item to an ItemModel so you can attach validation:
class ItemModel(item: Item) : ItemViewModel<Item>(item) {
val name = bind(Item::nameProperty)
val number = bind(Item::numberProperty)
}
class MainView : View("Example") {
val items = listOf(Item("One", 1), Item("Two", 2)).observable()
override val root = vbox {
tableview(items) {
column("Name", Item::nameProperty).makeEditable()
column("Number", Item::numberProperty).cellFormat {
val model = ItemModel(rowItem)
graphic = textfield(model.number, NumberStringConverter()) {
validator {
if (model.number.value == 123) error("Invalid number") else null
}
}
}
}
}
}
It will look like this:
While it works, it's sort of wasteful since the nodes are recreated frequently. I would recommend approach number one if performance is a concern, until we get cellFragment support for TableView like we have for ListView.
EDIT: I implemented cellFragment support, so it's possible to create a more robust solution which will show a label when not in edit mode and a validating textfield when you enter edit mode.
class ItemModel : ItemViewModel<Item>() {
val name = bind(Item::nameProperty)
val number = bind(Item::numberProperty)
}
class MainView : View("Example") {
val items = listOf(Item("One", 1), Item("Two", 2)).observable()
override val root = vbox {
tableview(items) {
column("Name", Item::nameProperty).makeEditable()
column("Number", Item::numberProperty).cellFragment(NumberEditor::class)
}
}
}
class NumberEditor : TableCellFragment<Item, Number>() {
// Bind our ItemModel to the rowItemProperty, which points to the current Item
val model = ItemModel().bindToRowItem(this)
override val root = stackpane {
textfield(model.number, NumberStringConverter()) {
removeWhen(editingProperty.not())
validator {
if (model.number.value == 123L) error("Invalid number") else null
}
// Call cell.commitEdit() only if validation passes
action {
if (model.commit()) {
cell?.commitEdit(model.number.value)
}
}
}
// Label is visible when not in edit mode, and always shows committed value (itemProperty)
label(itemProperty) {
removeWhen(editingProperty)
}
}
// Make sure we rollback our model to avoid showing the last failed edit
override fun startEdit() {
model.rollback()
}
}
This will be possible starting from TornadoFX 1.7.9.