I'm not fully understanding binding. I have a cont...

# tornadofx

[Brian]

I'm not fully understanding binding. I have a controller with a couple of properties (of type Int and of type String) that I want to bind to labels on the view.

[Nikky]

i think i can help when you share some of your code

most likely zou make a copy of the value at some point and the observable then does nto actually get updates

the class to use would be SImpleStringProperty for Strings

[Brian]

Here's an abbreviated bit of the relevant code:

class Combatant(name: String) {
    val experienceProperty = SimpleIntegerProperty(100)
    var experience by experienceProperty
}

class EncounterBuilderController : Controller() {
    val availableCombatants = SimpleListProperty<Combatant>(observableList(direBadger, goblin))
    val selectedCombatants = SimpleListProperty<Combatant>(observableList())

    val experiencePoints: Int
        get() = selectedCombatants.map { it.experience }.sum()

    val challengeRating: String
        get() = challengeRatingFor(experiencePoints)

    fun addCombatant(combatant: Combatant?) {
        if (combatant != null) {
            selectedCombatants += combatant
        }
    }
}

class EncounterBuilderView : View("Encounter Builder") {
    val controller: EncounterBuilderController by inject()
    override val root = vbox {
        label("Encounter XP:")
        label(stringBinding(controller.experiencePoints) {
            "%,d".format(controller.experiencePoints)
        })
        label("CR:")
        label(controller.challengeRating)
    }
}

[Brian]

I think that the key thing here is that I don't understand how to wrap a dynamic Kotlin property into an observable or a JavaFX property.

[Nikky]

challengeRating depends on a int val, that will never update

[Nikky]

you want a val experiencePointsProperty = integerBinding(selectedCombatantsProperty) {...}
and val experiencePoints by experiencePointsProperty

[Nikky]

selectedCombatantsProperty has to be a ListProperty too

[Nikky]

and then the label will be created like this: label(controller.challengeRatingProperty)

[Nikky]

same for experiencePoints

[Brian]

Thank you! I'll definitely give that a try.

[Brian]

Awesome! That did it! Thank you again.