Hi Jon,
Thanks for creating Wicket :-)
The first part of your message implies to me that you want to merge the
markup of MyComponentDecorated.html and MyComponent.html - is that correct?
Because I don’t read that in this sentence ("To restate the problem, what I
want to do is have MyComponent load either MyComponent.html or
MyComponentDecorated.html depending on the state of some variables
associated with MyComponent.”).
The simplest way to do this is with a variation, I think. Perhaps there are
better ways, but it worked well for me so far.
Basically - switch between variations by overriding
“Component#getVariation()” for a particular component and then wicket
automatically tries to load that variation of markup.
Based on your state you can return null or “decorated” from getVariation()
and thus use MyComponent.html or MyComponent_decorated.html;
That does mean that you need to repeat the html in MyComponent.html in
MyComponent_decorated.html and add any extra html there. So no automatic
merging and some duplication of the “base” html.
Now having said the above, and having hacked quite some of the wicket
internals: markup merging happens at load time.
So If you really wanted to do this, I think you’ll need to manage it
yourself. But since you are dealing with a single MyComponent which has two
different markup variations, the default classes will not work
(InheritedMarkupMarkupLoader expects a wicket:extends tag to reference a
parent component for the “parent” markup).
Should not be that difficult to make this work, but will involve a custom
markup loader and some custom logic for getMarkupResourceStream(), as you
were already working on.
Usually when I consider going down a rabbit hole like that, I first ask
myself: is that really worth the effort and maintenance burden? 🙂
I guess it depends based on how many components like this you have and/or
if you are getting the html from an external system (and thus need to work
with that).
Another strategy I would consider here is putting the “decorated”
components inside a fragment, co-located inside MyComponent.html.
Then you can either dynamically show/hide or swap the decorated fragment
with an EmptyPanel based on your internal state.
Met vriendelijke groet,
Kind regards,
Bas Gooren
Op 13 nov 2025, 00:36:39 schreef Jonathan Locke <[email protected]>:
> Hello All!
>
> I seem to have discovered after quite a lot of effort that it's not
> possible to dynamically swap the markup of a base component from which
> children inherit markup with <wicket:child/> and <wicket:extend/>. I think
> this makes sense because of how wicket merging and caching work (or at
> least used to work), but I just wanted to make sure that this is the case
> because it's been a long time since I worked on Wicket internals. To
> restate the problem, what I want to do is have MyComponent load either
> MyComponent.html or MyComponentDecorated.html depending on the state of
> some variables associated with MyComponent. In the case where the component
> is decorated, some components might be added and those components would be
> referenced in MyComponentDecorated.html. In the case where there are no
> decorations applied to the component, then no decorative components would
> be added and MyComponent.html would not provide references to decorations.
> I've tried a variety of ways of doing this, but it does not seem to be
> possible. I thought I had it for a moment by overriding both
> getMarkupResourceStream and getCacheKey, but that effort failed as well.
>
> Thoughts? Ideas? Thanks!
>
> Best,
>
> Jon
>
>
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