Undefined property: stdClass::$id when retriving term ID

Question

I have the following:

foreach( $this_post_terms as $term ) :
  $thiscat = get_term_by( 'slug', $term->slug, 'categories_whatever' );
  echo $thiscat->ID;
endforeach;

The last line throws an error, Undefined property: stdClass::$ID.

What's weird to me is that

echo $thiscat->name;

works, doesn't throw any error.

Answer 1

The fields returned by get_term_by() are:

• term_id
• name
• slug
• term_group
• term_taxonomy_id
• taxonomy
• description
• parent
• count

So instead of $thiscat->ID, you should use $thiscat->term_id

Ref: http://codex.wordpress.org/Function_Reference/get_term_by

Answer 2

Not weird, there is no ID in a term object, it's term_id. You can also var_dump($thiscat) in your loop to see all of its properties.