Trying to get property ‘ID’ of non-object in /wp-includes/class-wp-query.php on line 4044

Pixeldust WordPress Developer

3 years ago

I’ve made a custom plugin, but somehow I’ve made something that fills up my debug.log with garbage. It looks a bit like something this is faulty in the WordPress-core, but I’m not 100% sure.

Here is an extract of one of the 3 errors, that get’s repeated 5 times per page request:

PHP Notice:  Trying to get property 'ID' of non-object in /wp/wp-includes/class-wp-query.php on line 4044
PHP Stack trace:
PHP   1. {main}() /index.php:0
PHP   2. require() /index.php:4
PHP   3. wp() /wp/wp-blog-header.php:16
PHP   4. WP->main() /wp/wp-includes/functions.php:1291
PHP   5. WP->parse_request() /wp/wp-includes/class-wp.php:750
PHP   6. apply_filters() /wp/wp-includes/class-wp.php:379
PHP   7. WP_Hook->apply_filters() /wp/wp-includes/plugin.php:189
PHP   8. MyCustomClass->some_method() /wp/wp-includes/class-wp-hook.php:303
PHP   9. WP_Query->is_front_page() /wp-content/plugins/my-custom-made-plugin/my-custom-made-plugin.php:115
PHP  10. WP_Query->is_page() /wp/wp-includes/class-wp-query.php:3954

How I read the error-log statement

To sum up the error, this is how I read the error-log:

—

Trace#7: WP_Hook->apply_filters() /wp/wp-includes/plugin.php:189

I register MyCustomClass (from my Plugin) on the filter: request, like this:

add_filter( 'request', [ $this, 'some_method' ], 1, 1 );

—

Trace#8: MyCustomClass->some_method() /wp/wp-includes/class-wp-hook.php:303

MyCustomClass->some_method() calls is_front_page(), like this:

public function some_method( $query ) {
  $my_query = new WP_Query(); 
  $my_query->parse_query( $query );
  
  if ( $my_query->is_admin() || $my_query->is_home() || $my_query->is_front_page() ) {
    return $query;
  }
  ...
  ...

—

Trace#9: WP_Query->is_front_page() /wp-content/plugins/my-custom-made-plugin/my-custom-made-plugin.php:115

From there, the is_front_page() is called:

WordPress Core function: https://github.com/WordPress/WordPress/blob/5.8.3/wp-includes/class-wp-query.php#L3954

—

Trace#10 WP_Query->is_page() /wp/wp-includes/class-wp-query.php:3954

Which calls is_page():

WordPress Core function: https://github.com/WordPress/WordPress/blob/5.8.3/wp-includes/class-wp-query.php#L4044

—

Which throws the PHP Notice: Trying to get property ‘ID’ of non-object in /wp/wp-includes/class-wp-query.php on line 4044

Since I assume there is no ID on $page_obj.

BUT WHY?!

Does WordPress Core lack a check, if there is an ID on that $page_obj or am I using the function incorrectly?

Full Debug.log extract

This is what I get in the debug.log-file. And these below-written lines are written 5 times per page load, which is approximately 180 lines added to the debug.log, for every page that is loaded.

PHP Notice:  Trying to get property 'ID' of non-object in /wp/wp-includes/class-wp-query.php on line 4044
PHP Stack trace:
PHP   1. {main}() /index.php:0
PHP   2. require() /index.php:4
PHP   3. wp() /wp/wp-blog-header.php:16
PHP   4. WP->main() /wp/wp-includes/functions.php:1291
PHP   5. WP->parse_request() /wp/wp-includes/class-wp.php:750
PHP   6. apply_filters() /wp/wp-includes/class-wp.php:379
PHP   7. WP_Hook->apply_filters() /wp/wp-includes/plugin.php:189
PHP   8. MyCustomClass->some_method() /wp/wp-includes/class-wp-hook.php:303
PHP   9. WP_Query->is_front_page() /wp-content/plugins/my-custom-made-plugin/my-custom-made-plugin.php:115
PHP  10. WP_Query->is_page() /wp/wp-includes/class-wp-query.php:3954
PHP Notice:  Trying to get property 'post_title' of non-object in /wp/wp-includes/class-wp-query.php on line 4046
PHP Stack trace:
PHP   1. {main}() /index.php:0
PHP   2. require() /index.php:4
PHP   3. wp() /wp/wp-blog-header.php:16
PHP   4. WP->main() /wp/wp-includes/functions.php:1291
PHP   5. WP->parse_request() /wp/wp-includes/class-wp.php:750
PHP   6. apply_filters() /wp/wp-includes/class-wp.php:379
PHP   7. WP_Hook->apply_filters() /wp/wp-includes/plugin.php:189
PHP   8. MyCustomClass->some_method() /wp/wp-includes/class-wp-hook.php:303
PHP   9. WP_Query->is_front_page() /wp-content/plugins/my-custom-made-plugin/my-custom-made-plugin.php:115
PHP  10. WP_Query->is_page() /wp/wp-includes/class-wp-query.php:3954
PHP Notice:  Trying to get property 'post_name' of non-object in /wp/wp-includes/class-wp-query.php on line 4048
PHP Stack trace:
PHP   1. {main}() /index.php:0
PHP   2. require() /index.php:4
PHP   3. wp() /wp/wp-blog-header.php:16
PHP   4. WP->main() /wp/wp-includes/functions.php:1291
PHP   5. WP->parse_request() /wp/wp-includes/class-wp.php:750
PHP   6. apply_filters() /wp/wp-includes/class-wp.php:379
PHP   7. WP_Hook->apply_filters() /wp/wp-includes/plugin.php:189
PHP   8. MyCustomClass->some_method() /wp/wp-includes/class-wp-hook.php:303
PHP   9. WP_Query->is_front_page() /wp-content/plugins/my-custom-made-plugin/my-custom-made-plugin.php:115
PHP  10. WP_Query->is_page() /wp/wp-includes/class-wp-query.php:3954

Ideas and info

Dumping my_query

If I add a dump before calling is_front_page(), then I can see that the method is available on that query:

public function some_method( $query ) {
  $my_query = new WP_Query(); 
  $my_query->parse_query( $query );
  
  vardump( $my_query ); // HERE! is_front_page() is available. 
  if ( $my_query->is_admin() || $my_query->is_home() || $my_query->is_front_page() ) {
    return $query;
  }
  ...
  ...

System info

WordPress version 5.8.3