Hello gnfb,
This is by design. Because that will raise a lot of questions. Like:
What if there are multiple categories set?
Should a parent or a child prioritize?
What about tags, or custom taxonomies.
I don’t want to make those decisions, because they will be different for everybody.
But I did implement a way to do this yourself with a bit of coding.
Below is the example I have in the FAQ.
function dfi_category ( $dfi_id, $post_id ) {
// all which have 'animals' as a category
if ( has_category( 'animals', $post_id ) ) {
//sub category
if ( has_category( 'cats', $post_id ) ) {
return 7; // cats img
} else if has_category( 'dogs', $post_id ) {
return 8; // dogs img
}
return 6; // default animals picture
}
return $dfi_id; // the original featured image id
}
add_filter( 'dfi_thumbnail_id', 'dfi_category', 10, 2 );
Hope this helps.
Let me know if I could do anything else to help, or if I could help with this code.
