How to create single observable value? - tornadofx

Question

I've got a top-level Controller object that is holding a reference to three objects (MyObject). I'd like to position these precisely on the page at any time, but I would like each object to also be editable, and I'm not really sure how to do that.
So far, I've got a class that extends ItemFragment and displays my individual items, like this:
class MyObjectFragment(o: MyObject) : ItemFragment<MyObject>() {
override val root = hbox {
...
}
}
Meanwhile, I have a top-level View with a reference to my controller, like this:
class TopLevelView : View() {
val controller = TopLevelController()
override val root = hbox {
add(MyObjectFragment(controller.myObject1))
...
add(MyObjectFragment(controller.myObject2))
...
add(MyObjectFragment(controller.myObject3))
}
}
And right now, all I have for the top level controller is this:
class TopLevelController() : Controller() {
val myObject1 = MyObject()
val myObject2 = MyObject()
val myObject3 = MyObject()
}
I'm trying to figure out what I need to do to wrap these objects as observable values. My first attempt was to add something like this to the init method of MyObjectFragment:
class MyObjectFragment(o: MyObject) : ItemFragment<MyObject>() {
init {
itemProperty.bind(o)
}
...
}
However, that method only takes an ObservableValue<MyObject>. What is the best way to get that to tie all of this together?

Answer 1

You can create an observable list of your objects like so:
class TopLevelController() : Controller() {
val myObjects = FXCollections.observableArrayList<MyObject>(MyObject(), MyObject(), MyObject())
}
Then in your TopLevelView, you can bind this list to a layout node's children property, and inflate the proper Fragment for each object:
class TopLevelView : View() {
val controller = TopLevelController()
override val root = hbox {
bindChildren(controller.myObjects) {
MyObjectFragment(it).root
}
}
}

Answer 2

I'll admit your requirements seem a little vague to me without more information. It'd be helpful to know more of what you want from the item fragments. Are they going to be in a list view or table? Or something more dynamic? And how exactly would they be editing? Would there be a save button or would you expect any input to commit those changes immediately?
import tornadofx.*
class MyObject() {
//val someProperty = SimpleObjectProperty<Something>()
//var some by someProperty
}
class MyObjectModel(myObject: MyObject? = null) : ItemViewModel<MyObject>(myObject) {
//val someBinding = bind(MyObject::someProperty)
}
class MyObjectFragment : ItemFragment<MyObject>() {
val model: MyObjectModel by inject()
override val root = hbox {
label("This is an MyObject Fragment")
//you would bind some control to the model binding in here. For example:
//textfield(model.someBinding)
}
init {
itemProperty.value = model.item
model.bindTo(this)
}
}
class TopLevelController : Controller() {
val myObject1 = MyObject()
val myObject2 = MyObject()
val myObject3 = MyObject()
}
class TopLevelView : View() {
val controller: TopLevelController by inject()
override val root = vbox {
add(setUpObjectFragment(controller.myObject1))
add(setUpObjectFragment(controller.myObject2))
add(setUpObjectFragment(controller.myObject3))
}
fun setUpObjectFragment(obj: MyObject) = find<MyObjectFragment>(Scope(MyObjectModel(obj)))
}
It also seems you're new and are missing a lot of key concepts to utilize from TornadoFX. Using find for instance, is really important for Fragments and Views so they have the proper life cycle.
Then there's Scopes which help with being able to call certain Components with injection.
And finally, there are Model classes, most importantly ItemViewModel which gives you the most functionality with editing, like being able to rollback and commit changes as well as to mark properties as required and add validate filters.
If this isn't a satisfactory solution, please give us more information on what you want, as I might be able to provide a more elegant and concise solution. If these concepts are confusing, please look at Edvin's guide.