Problem:
I have a Vaadin project
I’m dispatching a CustomEvent from a JS lit component.
I’m listening to it from a Java class and I correctly receive the events emitted.
The following is my JS code:
this.dispatchEvent(new CustomEvent('change', {detail: this.breakLines, bubbles: true, composed: true}));
And the following is my Java listener:
getElement().addEventListener("change", e -> {
System.out.println("change value: " + e.getEventData());
});
Currently my Java code outputs an empty object {}
How can I extract the data that resides in "detail"?
Solution:
Vaadin does not submit all properties of the event by default, you need to give it a hint. For example I’m doing this in my recent React example:
getElement().addEventListener("color-change", e -> {
var newValue = e.getEventData().getString("event.hex");
setModelValue(newValue, true);
})
.addEventData("event.hex")
In your case that could be:
.addEventData("event.detail")
And then accessing that boolean:
e.getEventData().getBoolean("event.detail")
Alternatively, you can create a custom event and declare the transferred details with annotations, as described in other answer, but that requires quite a lot more code.
