Check if post belongs to any category

Question

In my homepage loop, I have something that will show which category the post is in. It will say something like "Posted 4 hours ago in Sports by ...". However, when there is no category set, it will omit the category (obviously) and just say "Posted 4 hours ago in by ...". My question is: how do I check if a post belongs to any category in WordPress.

I know that the function in_category() exists, but I would like to avoid having to type out all of the categories, in case they change, or whatever.

Thanks!

Answer 1

You can use is_object_in_term(). Despite name it can also check for taxonomy match if terms are omitted.

is_object_in_term( get_the_ID(), 'category' );

Answer 2

Instead of using get_category() or whatever to echo it out directly, try using get_the_category(), which will simply return an array of the categories. You can then spin through those items and check if they are empty() or not.

Maybe something like:

$categories = get_the_category( $post->ID );
if( is_array(categories) && count($categories) > 0 ) {
  foreach( $categories as $category ) {
    $categories_string .= $category . ", ";
  }
  $categories_string = rtrim(", ", $categories_string);
}

if( !empty( $categories_string ) ) {
  echo "Posted 4 hours ago in {$categories_string} by ...";
} else {
  echo "Posted 4 hours ago by ...";
} 

*untested

Answer 3

use has_category() wp 3.1+ needed though