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Generating commented-out content with Wicket

Answer 1

+2 A:

Label l = new Label("foo", "<!-- " + foo + " -->");
l.setEscapeModelStrings(false);

Its not pretty but it's quick and easy. I also believe there is a specific wicket setting (somewhere in application) which which you can turn on to prevent it from stripping comments, but I honestly can't remember where I saw it.

Edit: Added comment worker

Edit2: Implemented Eelco's behaviour for completeness. Its better than my approach anyway.

public enum Comment {
;
    /**
     * creates a wicket comment (extends label
     */
    public static Label newComment(String id, String comment) {
        Label label = new Label(id, comment);
        label.add(commentBehaviour());
        return label;
    }

    /**
     * Adds &lt;!-- and --&gt around the component.
     */
    public static AbstractBehavior commentBehaviour() {
        return new AbstractBehavior() {
            private static final long serialVersionUID = 1L;

            @Override
            public void beforeRender(Component component) {
                component.getResponse().write("<!--");
            }

            @Override
            public void onRendered(Component component) {
                component.getResponse().write("--!>");
            }
        };
    }
}

add(Comment.newComment("comment","Something worth commenting upon"));

BjornS 2010-10-14 14:01:36

Thanks; this works ok for my current need. (And can be made a little bit cleaner with `String.format()`.) I'll accept this after a while, unless something obviously better comes up.

Jonik 2010-10-14 14:16:07

@Jonik I think this is *the* way to do it so don't hold your breath :)

jensgram 2010-10-14 14:22:02

You inspired me to make this: public enum Comment { ; public static Label newComment(String id, String comment) { Label label = new Label(id, String.format("<-- %s -->", comment)); label.setEscapeModelStrings(false); return label; }} add(Comment.newComment("comment","foo bar goes here"));

BjornS 2010-10-14 14:30:14

@Bjorn, your previous comment would be easier to read if edited into the answer. :) But personally I'd prefer this for reusability (similarly as I commented on [Tim's answer](http://stackoverflow.com/questions/3933921/generating-commented-out-content-with-wicket/3934240#3934240)): create custom component (CommentedLabel extends Label) whose constructor takes care of adding the HTML comments and calling setEscapeModelStrings(false).

Jonik 2010-10-14 14:57:25

Added to final answer. I guess using the worker class method is matter of preference, in our trunk we already have faaar too many label types, though one I can recommend making would simply be HTMLLabel :) In my own code trunk the example above uses HTMLLabel to avoid having to setEscapeModelStrings(false)

BjornS 2010-10-14 15:08:05

Almost off-topic: that (mis)use of `enum` strikes me as odd though. That's just a static utility method, so I'd put it in a (normal) class called Comments, or WicketUtils or so (along with other such methods).

Jonik 2010-10-14 15:17:10

You're right that it is not a typical use of enum, however I've had great success with this style of coding, especially in a WicketEnvironment. Enums are implicitly serializable and singleton (if that were required and this example was instancable). It also lends itself very nicely to shorter classes, no need to serializable ID, private constructors etc and Eclipse picks up on them nicely. However you are right, if we had a WicketUtil, it should certainly go there :)

BjornS 2010-10-15 07:12:10

Answer 2

+1 A:

Played around a little and got to this:

Label label = new Label("commented", "Content") {
    @Override
    protected void onComponentTag(ComponentTag tag) {
        tag.setName("!--");
        super.onComponentTag(tag);
    }
};
add(label);

But it's not pretty..: <span wicket:id="commented">This will be replaced</span>
becomes: 

But at least it won't interfere with layout / css styles.

Tim 2010-10-14 14:28:54

+1, interesting hack. :) The good thing about this is that you could create a custom component (CommentedLabel extends Label) which overrides onComponentTag(), and after that using this on pages is very clean.

Jonik 2010-10-14 14:47:18

... which of course you can do that with Bjorn's solution too, so no big difference there. I guess it's a matter of taste which of these is less "non-pretty". :)

Jonik 2010-10-14 15:01:08

Does Wicket convert the closing tag? Or did you mean ``? (Note the `!` - not that it matters.)

jensgram 2010-10-14 15:11:51

Yeah, @jensgram is right: it comes out as `</!-->` (but works nonetheless)

Jonik 2010-10-14 15:18:55

@jensgram Yup, you're right.. the close tag had a ! as well.. (Didn't copy-past that part.. =\)

Tim 2010-10-14 17:58:41

Answer 3

+1 A:

How about this?

class CommentOutModifier extends AbstractBehavior {
    private static final long serialVersionUID = 1L;

    @Override
    public void beforeRender(Component component) {
        component.getResponse().write("<!--");
    }

    @Override
    public void onRendered(Component component) {
      component.getResponse().write("-->");
    }
}

add(new Label("tohide", "Hi, can you see me?").add(new CommentOutModifier()));

then, putting:

<span wicket:id="tohide"></span>

in your markup will yield:

<!--<span>Hi, can you see me?</span>-->

Eelco 2010-10-16 00:13:31

And the nice thing about that solution is that you can apply it to any component without changing the component itself.

Eelco 2010-10-16 00:14:45

Thanks! This looks pretty elegant.

Jonik 2010-10-16 09:32:32

If this works as I suspect then its quite an elegant solution, cudos :) I'm revising my answer to implement this method for the sake of completeness but I think Eelco deserves to get the answer for this.

BjornS 2010-10-18 07:48:35

It works; tested it to make sure. But don't take my word for it and give it a spin :-)

Eelco 2010-10-23 20:21:16

There was actually a bug in onRendered: it used "--!>" instead of "-->". Our front-end developer just noticed this broke the layout badly in IE on a page where I used the commented-out label! I took the liberty to fix the answer. :-)

Jonik 2010-10-26 13:56:32

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Generating commented-out content with Wicket

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