Fill JavaFX combobox by javascript class (Nashorn) - javafx

Question

I try to use my custom class which I have created in my script (the script is written in Nashorn) and after that I try to use this custom class to fill in as items in combobox. I know that if I want to see correct values in combobox that the class has to override method toString, but in this case I do not know much how can be overriden this method in my custom class written in Nahorn.
Below I provide my code where the variables cmbCategories is JavaFX combobox and CategoryItem which I try to use as object to fill in the items in combobox and display as category name.
I would appreciate any suggestion or ideas how can be this problem resolved.
var ClientBuilder = Java.type("javax.ws.rs.client.ClientBuilder")
var Platform = Java.type("javafx.application.Platform")
var Executors = Java.type("java.util.concurrent.Executors")
var Response = Java.type("javax.ws.rs.core.Response")
var String = Java.type("java.lang.String")
var List = Java.type("java.util.ArrayList")
Executors.newSingleThreadExecutor().execute(function () {
print("Calling for category data...")
var categoryData = ClientBuilder
.newClient()
.target(String.format("%s%s", "http://localhost:8080", "/client/action/categories"))
.request()
.get()
if(categoryData.getStatus() == Response.Status.OK.getStatusCode()) {
var categories = JSON.parse(categoryData.readEntity(String.class))
var categoryItems = new List();
for each (var category in categories) {
categoryItems.add(new CategoryItem(category.id, category.category))
}
Platform.runLater(function() {
cmbCategory.getItems().addAll(categoryItems);
});
} else {
print(categoryData.getEntity().toString());
}
})
function CategoryItem(id, name) {
this.id = id;
this.name = name;
this.toString = function () {
return this.name;
}
}

Answer 1

Use the ScriptEngine to retrieve an appropriate string in the cellValueFactory of the ComboBox.
Simplified example
#Override
public void start(Stage primaryStage) throws Exception {
ScriptEngineManager manager = new ScriptEngineManager();
final ScriptEngine engine = manager.getEngineByMimeType("application/javascript");
ComboBox<Object> comboBox = new ComboBox();
comboBox.setCellFactory(c -> new ListCell<Object>() {
#Override
protected void updateItem(Object item, boolean empty) {
super.updateItem(item, empty);
if (empty || item == null) {
setText("");
} else {
Bindings bindings = new SimpleBindings();
bindings.put("a", item);
try {
// use script engine to retrieve text
setText(Objects.toString(engine.eval("a.name", bindings)));
} catch (ScriptException ex) {
setText("Error");
}
}
}
});
comboBox.setButtonCell(comboBox.getCellFactory().call(null));
Bindings b = new SimpleBindings();
b.put("cmbCategory", comboBox);
engine.eval("function CategoryItem(id, name) {this.id = id;this.name = name;}\n"
+"var Platform = Java.type(\"javafx.application.Platform\")\n"
+ "var categories = [new CategoryItem(1, 'a'), new CategoryItem(2, 'b'), new CategoryItem(3,'c')]\n"
+ "for each (var category in categories) {cmbCategory.getItems().add(category);}", b);
Scene scene = new Scene(new StackPane(comboBox));
primaryStage.setScene(scene);
primaryStage.show();
}
I don't see the purpose of using JavaScript for this though. Everything you do in the javascript code could be done from java code more efficiently...