Flow: TextField.getValue() always return an empty string

[mvysny]

I have cloned the https://github.com/vaadin/skeleton-starter-flow project, ran mvn jetty:run on it and modified the MainView's constructor to look like this:

    public MainView() {
        ExampleTemplate template = new ExampleTemplate();

        final TextField foo = new TextField("Foo");
        Button button =  new Button("Click me", event -> template.setValue("Clicked! " + foo.getValue()));
        add(button, template, foo);
    }

When I click the "Click me" button, I want the text I've entered into the "Foo" field to appear along the "Clicked! " string. Instead, it comes up empty.

[mvysny]

It's Flow 1.0.0.alpha3

[ZheSun88]

In fact, you can use this way to achieve your goal:

foo.addValueChangeListener(event -> event.getValue());
button.addClickListener(event -> {
     template.setValue("Clicked! " + foo.getValue());
});

If i recall correctly, in your way, the foo.getValue() is getting the initial value from the textField which is empty and it doesn't fire an event until you add a listener to it.. :)

[mvysny]

Ah, so the value is not transferred to the server side until the value change listener is added :) that's why it worked in the beverage demo - it uses binder which internally sets the value change listener.

Anyways, I believe that the value change listener should not be required in order for the value to be transferred from client to server.

[ZheSun88]

yes, the usage maybe look not very straightforward as using getValue() directly, but change listener is used to sync the value from the client to server.

[pleku]

We should be making the TextField send the value to the server always on e.g. blur event when there has been a change, even if there is no ValueChangeListener applied.

Without that, we will confuse some users (like now), and that is always a bad thing. This is pretty similar what we had in FW 6 & 7 with the immediate property.

[ZheSun88]

Issue moved to vaadin/vaadin-text-field-flow #4 via ZenHub