KeyBoardEvents cause error on serverside with IE Edge

[mikotin]

KeyBoardEvent requires a "isComposing" property and Edge doesn't give such so using standard keyboard events (KeyDownEvent, KeyPressEvent, KeyUpEvent) will cause exception on creation of given event:

java.lang.IllegalArgumentException: Unable to create an event object of type com.vaadin.flow.component.KeyUpEvent
	at com.vaadin.flow.component.ComponentEventBus.createEventForDomEvent(ComponentEventBus.java:362)

Test:

Input input = new Input();
input.addListener(KeyUpEvent.class, keyUpEvent -> {
	// throws java.lang.IllegalArgumentException: 
	// with Edge
	if (keyUpEvent.getKey().equals(Key.ENTER)) {
		System.out.println("We got enter!");
	}
});

The data that actually comes from client to server:

In the end this is (isComposing) only a boolean value so probably it could just fall back to false in this (or other similar) cases.

[pleku]

I think for missing boolean properties we could just set the default to false if it is missing from the json received. I would find this much better DX than the error.

[Legioth]

Another alternative for this particular case would be to change the definition from event.isComposing to !!event.isComposing so that null and undefined would be coalesced to false.

[pleku]

After a discussion @mikotin we decided to add a way to handle the special cases of missing event data with an optional second parameter for the annotation that states the default value as a String. Thus when facing a missing parameter from client side, Flow will try to convert the value given in the string (if any) to the corresponding type in the event constructor. Eg. for this case, it would be
@EventData("event.isComposing", "false").
It lets you use eg. experimental API event data with all the browsers without being afraid that things will explode. The default usage of the @EventData stays unaffected.

[Legioth]

@EventData("event.isComposing", "false") won't compile, but @EventData(value = "event.isComposing", default = "false") would.

Would support for default values then also be implemented for DomListenerRegistration.addEventData which the @EventData annotation is based on?

[pleku]

Oops for the first one, I don't see why not (adding overrides) for the second one.

Also we should update the related tutorials https://github.com/vaadin/flow-and-components-documentation/search?l=AsciiDoc&q=EventData&type=

[Legioth]

What would happen if there are multiple addEventData calls or @EventData annotations that define different default values for the same expression?

[Legioth]

Concluded that instead of allowing to explicitly configure default values, we should simplify this by explicitly checking for primitive @EventData parameters and in that case convert a missing or null value to the corresponding default value (i.e. false, 0 or 0.0 for the three types that are currently supported). These are also the values that you get with asBoolean() or asNumber() from a JsonNull value.

If the developer wants to distinguish between e.g. false and a missing value, then they can change the parameter type from boolean to Boolean and handle a null value in their own code instead.