Bind ItemViewModel to domain class list - tornadofx

Question

I have a Rulebook that contains Rules:
class Rulebook(val rules:MutableList<Rule>)
I have an ItemViewModel for it, as it's used in a multiply-nested selection UI.
class RulebookModel : ItemViewModel<Rulebook> {
val rulesProperty = bind // ... here's my problem
}
What is the correct binding to be able to initialize a tableview with the property?
A naive bind yields the wrong type:
val rulesProperty = bind(Rulebook::rules)
has type Property<MutableList<Rule>>, which tableview() doesn't take.
From another answer here I got Link
val rulesProperty = bind(Rulebook::rules) as ListProperty<Rule>
This yields the correct type, so we get through compilation, but at runtime I get this:
java.lang.ClassCastException: java.util.ArrayList cannot be cast to javafx.collections.ObservableList
Note: The RulebookModel does start life without an item in it yet. I've seen ArrayLists come from empty list factory calls before. Is that possibly my actual problem?
What is the correct way to perform this binding?

Answer 1

Your model needs to have a SimpleListProperty to bind into an itemViewModel
Here is some sample code for how to write the classes and a table view:
data class rule(val name: String, val def: String)
class RuleBookModel{
val rulesProperty = SimpleListProperty<rule>()
var rules by rulesProperty
}
class RuleBookViewModel: ItemViewModel<RuleBookModel>() {
val rules = bind(ruleBook::rulesProperty)
}
class TestView : View("Test View") {
val myRuleBook: RuleBookViewModel by inject()
init {
// adding a rule so the table doesn't look lonely
myRuleBook.rules.value.add(rule("test", "fuga"))
}
val name = textfield()
val definition = textfield()
override val root = vbox{
hbox {
label("Name")
add(name)
}
hbox {
label("Definition")
add(definition)
}
button("Add a rule").action{
myRuleBook.rules.value.add(rule(name.text, definition.text))
}
tableview(myRuleBook.rules) {
column("name", rule::name)
column("def", rule::def)
}
}
}