I want to make post filter "by custom taxonomies" that acts this way:
- two lists of taxonomy terms (A and B) with checkboxes
- user selects term(s) from first list (taxonomy A)
- second list (taxonomy B) refreshes automatically: it show's only terms, existing in posts, where selected terms from taxonomy A exist
Actually it means taxonomy list B depends on taxonomy A selected terms through posts. I have no idea how to get list B. Only brute-forse one: getting all posts filtered by A with regular WP_Query and walking throug it getting terms B from every post and checking for possible duplicates.
Please help me to find the right way.
