I wanna have

  • example.com/post-name -> uses template1.php

  • example.com/post-name/details -> uses template2.php

I found this discussion, so I implemented the codes in my theme’s functions.php. I also made the changes from the older replies but I get this error

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'detail_rewrite_rules' not found or invalid function name in /public_html/wp-includes/plugin.php on line 173

I didn’t edit plugin.php and on line 173 is:

$value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));

I hope someone can help me, it seems a fairly easy job but I might be wrong.

1 Answer 1


If you look at the function you'll see there's an error :

function detail_rewrite_rule( $rules ) {
  $newrules = array();
  $newrules['(.+?)/([^/]+)(/[0-9]+)?/detail/?$'] = 'index.php?category_name=$matches[1]&name=$matches[2]&page=$matches[3]&detail=1'; 

  return $newrules + $rules;
add_filter( 'rewrite_rules_array','detail_rewrite_rules' );

The callback is not the same : detail_rewrite_rule, detail_rewrite_rules.

In the add_filter you have to provide the same name for function. Otherwise this won't be hooked in WordPress. So you can fix it with :

add_filter( 'rewrite_rules_array','detail_rewrite_rule' );//without the s
  • Thank you for your answer @jMau , yes that was the problem, but now i get this error >Fatal error: Can't use function return value in write context in /home/keezme/public_html/wp-content/themes/vid/functions.php on line 1596` , on line 1596 i have ` return (!empty(locate_template($templates))) ? locate_template($templates) : $template;` if i remove the line, the error disapear but the code is not working , if i go to example.com/mypost/detail/ i get a 404 error Aug 22, 2013 at 11:26
  • I did not check the function. But with a quick look I can see this is not great quality. You'd better ask a detailed question here.
    – JMau
    Aug 22, 2013 at 11:29

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