[TwigComponent] Merge data-action in ComponentAttributes

[weaverryan]

Q	A
Bug fix?	yes
New feature?	no
Issues	None that I know of
License	MIT

If you pass data-action into a component & the root attributes has a data-action already thanks to attributes.defaults, they should be merged together. Same behavior as data-controller. I found this while adding a data-action to a component and suddenly losing my existing data-action from inside.

Cheers!

[norkunas]

What if I want to override the data-action totally, will it be possible? :)

[weaverryan]

What if I want to override the data-action totally, will it be possible? :)

Nope :). It's a valid question. Right now, data-controller and class are already "merge". This is hardcoded in. I've talked with @kbond a bit about adding some sort of API to replace vs merge. That's something we need to add. In the mean time, this is the "closer to proper" behavior.

So, we can't have it both ways right now. Currently, it's not possible to merge a data-action from the inside with a data-action from the outside. However, at the very least, you could introduce some other "prop" flag and use that to turn on / off an internal data-action after this PR. Since data-controller merges, this is closer to the correct behavior.