Allow searching for classes

[nicolas-raoul]

I wanted to search for types of cheese (camembert, bleu, etc).

Obviously camembert is a subclass of cheese, not an instance of cheese.

I haven't found a way to search for this.

[aidhog]

Yes, at the moment we require starting with a keyword search or a type, while it seems classes/types in Wikidata don't have an instance-of value. Probably the best way to address this would be to build a super-facet over all entities and just let users skip the type selection. This is something we will postpone for now since computing that super-facet is not trivial, and the interface would require adjusting maybe to not show all facet-properties at once.