ikiwiki/ forum/ Howto add tag from plugin code

Hi, I want to add tags to some pages automatically (generating album images and want to tag all generated pages). I managed to do so in following way:

IkiWiki::Plugin::tag::preprocess_tag(
    page => $viewer,
    destpage => $params{destpage},
    map { ($_ => 1) } @tags,
);

This works, however if some tag does not exist, it is not created. I tracked it so far that I found that the Render.pm's method gen_autofile() is not called , so it is most likely that I need to somehow trigger Render.pm's refresh()...but how can I do it?

BTW: The code is modified album plugin that is in my git

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(If you want to branch from my version of album, please add my git repo as a remote and merge or cherry-pick the album4 branch: pasting from my gitweb seems to have given you some incorrect UTF-8.)

The problem you have here is that for this plugin, the correct order for IkiWiki to do things is quite subtle. Am I right in thinking that the feature you want goes something like this?

To add a set of tags to every "viewer" page in the album, you can add the tags parameter to the album:

\[[!album tags="holiday hawaii"]]

The individual viewers will all be tagged "holiday" and "hawaii", for instance. These tags cannot be removed by editing the viewers.

preprocess_albumimage runs twice: once in the scan stage, and once in the render stage. In the render stage, it's too late to add tags, because tags are a special form of ?wikilinks, and wikilinks have to be added during the scan stage to work correctly.

The part of preprocess_albumimage after the line return unless defined wantarray; only runs in the render stage, which is too late. You'd need to set up the tags further up: just after the calls to IkiWiki::Plugin::meta::preprocess would be a good place.

I would also suggest checking for IkiWiki::Plugin::tag->can('preprocess_tag'), like I do for meta - if you do that, you won't need to force the tag plugin to be loaded.

Unfortunately, I'm still not sure that this is fully correct. Pages are scanned in a random order. If the \[[!album]] is scanned before a "viewer" page, then everything is fine: the tags are present when the "viewer" is scanned. However, if the "viewer" is scanned first, then it will get the tags that the \[[!album]] had in the previous IkiWiki run (if any), which are still in the index, because the \[[!album]] hasn't been re-scanned yet...

Are you sure this form of the feature is what you want? You'll end up with a lot of pages with those tags. If it's what you want, it might be clearer how it works if you changed the syntax to something like this, perhaps?

\[[!album tag_all="holiday hawaii"]]

Another possible syntax would be to have the feature be more like this:

If you use the tag_default parameter to the \[[!album]] directive, each "viewer" page created for images will have those tags by default. Changing the \[[!album]] will not affect any "viewer" pages that have already been created, and editing the "viewer" can add or remove those default tags.

\[[!album tag_default="holiday hawaii"]]

which I think removes the ordering problems? If you go this route, you'd want to either add e.g. [[!tag holiday hawaii]] to the generated viewer page in create_viewer, or add a tag parameter to \[[!albumimage]] that's a shortcut for the tag directive, in the same way that author is a shortcut for [[!meta author]]).

The purpose of the "shortcut" parameters in \[[!albumimage]], like title, author and date, is that I eventually want to add a specialized CGI interface to this plugin so you can edit all the images of an album in one go; when I add that, it'll probably only be able to process something as machine-readable as \[[!albumimage]].

Comment by smcv — Mon Jul 1 05:13:51 2013
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