First, some other filter-builders I’ve come across, if you’d like to see how other developers have approached it:
- @EricShulman’s PowerSearch (find it on https://tiddlytools.com, either through the search dropdown or the tab on $:/AdvancedSearch)
- TiddyWiki xp’s FilterBuilder (the wiki itself is mostly in Chinese, but that particular tiddler is all English, and the rest of the site translates well)
Re: your specific question: You can use the actions attribute of a $select widget to modify a separate field (or tiddler). For instance, you could define an $action-setfield widget to modify/append your selection(s) to the existing filter, as Mat suggests.
In theory, I suppose you could use actions on a $select to further modify the field where it stores its selection, but I really wouldn’t recommend it.
- Any changes to the field defined by the
$select field=attribute will remove the record of your last selection, and this will make it difficult to replace or remove a specific piece of the composite filter. - I think you’d also be likely to encounter the ever-growing filter problem we discussed yesterday.