Get only the pages (categories) which are referenced by other pages

[Torsten Baldes]

hi,

i'm kind of „brain blocked“ right now and need your help.

i've got a lot (> 1000) articles which have a page field (single page) to reference a category.

there are a lot categories, which not all are in use right now.

now i need a selector to get only these categories which are referenced by an article. 

how would you do this?

thanks!

[LostKobrakai]

https://processwire.com/talk/topic/9730-get-pages-used-by-a-pagefield/

[Torsten Baldes]

thanks! 

i didn't found this thread when i searched the forum.

i use now your first approach. an addition to the API would be a nice feature!