[isarl]

Originally Posted by Katja_hbg

And this is the killer.
I use "collection columns" with three fields. One of the is tags.
After being happy with that for years, today I had the idea to reduce the values coming out of "tags".

Thanks again for your help but after having some fun to give it a try, I will continue with former setting.

You're so close! There's no need to give up when you're so close.

Any tags you do NOT want processed by the template, leave in your Collections Columns field.

Any tags which you DO want processed by the template, make sure they are NOT in the Collections Columns field, and that your template logic handles these other fields correctly.

For example, if I have Genre (#genre), Collections (#collections), and Tags (tags – this is a builtin column, so no #prefix for it), and I only wanted to perform this custom processing on the tags, then I would put #genre, #collections in the “Collections Columns”. And for the template I would use something like we described previously:

program:
# Remove tags listed in tags_to_ignore
	tags_to_ignore = 'danach, kurz';
	list_join(':@:', list_difference($tags, tags_to_ignore, ','), ',')

Just remember: if you want to process a column before using it as collections, then you need to put that column into a template, not in your “Collections Columns” setting. The “Collections Columns” setting is only for data that will be used as-is.