WP_Error with get_category_parents

Question

I get this error in my theme:

Catchable fatal error: Object of class WP_Error could not be converted to string in /home/winentra/public_html/s1.ssonline.co.in/wp-content/themes/peekaboo/admin/common-functions.php on line 186

Line No. 186:

echo get_category_parents($cat, TRUE, ' ' . $delimiter . ' ');

Context:

 elseif ( is_single() ) {
          $cat = get_the_category(); 
              $cat = $cat[0];
          echo get_category_parents($cat, TRUE, ' ' . $delimiter . ' ');
          echo $currentBefore;
          the_title();
          echo $currentAfter;
}

Any ideas on this please?

Answer 1

If you call get_the_category() without a parameter you have to use it in a loop – after the_post(); was called. Otherwise get_the_category() returns FALSE and get_category_parents() returns a WP_Error object … which is lacking a toString() method and therefore cannot be printed.

So test if you get an object or a string before you try to echo the return value.

Answer 2

What @toscho means is that here:

http://codex.wordpress.org/Function_Reference/get_category_parents

It clearly states that

Return Values

(string|WP_Error)

The categories, separated by $separator. WP_Error on failure.

So you can't assume the output will be string and echo it. It can also be a WP_Error object. You need to test it using:

http://codex.wordpress.org/Function_Reference/is_wp_error