Validate JavaFX form only after submission using ValidationSupport

Question

I'm trying to validate a javafx form using ValidationSupport, the validation is working, but when I access the form the "errors decorations" are already shown, even before the form is submitted or the textfield is focused.

ValidationSupport validationSupport = new ValidationSupport();
    validationSupport.registerValidator(textField, Validator.createEmptyValidator("Text is required"));

The following image shows an example of the form in its initial state.

How can I force the decoration to show only after the user submit the form or change the TextField value?

Answer 1

To validate controls on demand is an issue (on-demand validation option) on ControlsFx's issue tracker which is still open so ControlsFx does NOT support it yet.

But there is a way to suppress error decorations:

ValidationSupport validationSupport = new ValidationSupport();
validationSupport.setErrorDecorationEnabled(false);

Later, when you actually want to validate (on submit button for example) you need to reset it to default value:

validationSupport.setErrorDecorationEnabled(true);
validationSupport.redecorate();

This way, fields still get validated by every change but error decorations are not shown until you actually want them to be shown.

---

Example:

In this example we'd like to see validation errors only if number field has the focus.

public class Sandbox extends Application {
    @Override
    public void start(Stage primaryStage) throws Exception {
        GridPane pane = new GridPane();
        pane.add(new Label("Number field:"), 0 , 0);
        TextField numberField = new TextField("");
        pane.add(numberField, 1, 0);
        TextField textField = new TextField("");
        pane.add(new Label("Text field:"), 0, 1);
        pane.add(textField, 1, 1);

        ValidationSupport vs = new ValidationSupport();
        vs.setErrorDecorationEnabled(false); // we don't want errors to bother us for now.
        vs.registerValidator(numberField, Validator.createRegexValidator("must be digits only!", "\\d*", Severity.ERROR));

        // validate and show errors only if number field has the focus
        vs.errorDecorationEnabledProperty().bind(numberField.focusedProperty());

        primaryStage.setScene(new Scene(pane));
        primaryStage.show();
    }

    public static void main(String[] args) {
        Application.launch(Sandbox.class);
    }
}

or if you want to see validation errors only after submit button is clicked for the first time:

        ...
        Button button = new Button("Submit");
        pane.add(button, 0, 2);

        ValidationSupport vs = new ValidationSupport();
        vs.setErrorDecorationEnabled(false); // we don't want errors to bother us for now.
        vs.registerValidator(numberField, Validator.createRegexValidator("must be digits only!", "\\d*", Severity.ERROR));

        
        button.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent event) {
                vs.setErrorDecorationEnabled(true); // validate and show errors now!
            }
        });
        ...