Multiple WordPress URL Parameters Causes Undefined ID and Nicename Errors

[chriscct7]

So I was able to find an unexpected behavior in WordPress that looks like it was patched in #17662 11 months ago, since a closely related ticket, #20519, was closed and merged into that one.

Basically, to reproduce this you need a custom post type that supports authors.

So, let's say I have a cpt called 'download'. Let's say a known author ID is 1. It doesn't really matter what the author id is. Now, try going to:

mysite.com/?post_type=download&author=1

So what you'd expect to see, is the downloads archive template, with the posts written by author 1.

Instead what you get is undefined errors specifically undefined id and undefined nicename.

Not really sure where the bug comes from (my guess is maybe the templates for author and post type archives) so I've logged it under General.

[helen]

What theme/template code?

[chriscct7]

I'm not sure specifically which ones, but what I presume is happening is:
is_admin() returns true for this query, and is_archive() also returns true, so WordPress is either loading the author template, the archives template or possibly both. Let me see if I can track down something for you

[chriscct7]

Notice: Undefined property: stdClass::$user_nicename in C:\wamp\www\edd\wp-includes\template.php on line 88
Call Stack
#	Time	Memory	Function	Location
1	0.0002	675064	{main}( )	..\index.php:0
2	0.0003	679880	require( 'C:\wamp\www\edd\wp-blog-header.php' )	..\index.php:17
3	0.2930	36454520	require_once( 'C:\wamp\www\edd\wp-includes\template-loader.php' )	..\wp-blog-header.php:16
4	0.2942	36455504	get_author_template( )	..\template-loader.php:38

Notice: Undefined property: stdClass::$ID in C:\wamp\www\edd\wp-includes\template.php on line 89
Call Stack
#	Time	Memory	Function	Location
1	0.0002	675064	{main}( )	..\index.php:0
2	0.0003	679880	require( 'C:\wamp\www\edd\wp-blog-header.php' )	..\index.php:17
3	0.2930	36454520	require_once( 'C:\wamp\www\edd\wp-includes\template-loader.php' )	..\wp-blog-header.php:16
4	0.2942	36455504	get_author_template( )	..\template-loader.php:38

Looks like the author template

[chriscct7]

So there's 2 ways this could affect a site.
The first way is you get the xdebug notices.

The second way, is if you've elected to hide those errors, you get back a totally blank page, like on photomatt's site, where:
​http://ma.tt/?post_type=post&author=1
becomes
​http://ma.tt/author/saxmatt/?post_type=post

which is a blank page

[mordauk]

get_queried_object() is returning the post type object but since the author query arg is set, is_author() returns true, which causes the undefined index error when the title is set to the author's name with $title = $author->display_name;.

This can be fixed by adding && ! is_post_type_archive() to the is_author() check.

I'm not sure if there are any repercussions of this though.

[mordauk]

Add ! is_post_type_archive() to is_author() check

[wonderboymusic]

Unless I'm missing something, this appears to be fixed....

Canonical redirection is kicking in:
​http://wordpress-core-develop/?post_type=_type&post_author=1 redirects to
​http://wordpress-core-develop/author/admin/?post_type=_type

+ no errors when when pretty permalinks are off

[wonderboymusic]

Someone reopen if I'm wrong about this working just fine now.

[mordauk]

Still throws notices for me:

http://trunk:8888/?post_type=download&author=1 redirects to http://trunk:8888/author/pippin/?post_type=download and shows the query results correctly, but there are still undefined notices in the header:

​http://d.pr/i/DJcb

[wonderboymusic]

I still can't reproduce this - @mordauk, what theme are you using?

[mordauk]

Replying to wonderboymusic:

I still can't reproduce this - @mordauk, what theme are you using?

I tested on multiple default themes, including Twenty Twelve and Twenty Thirteen.

[wonderboymusic]

Ah, I couldn't reproduce it because I was using post_author in the URL, not author. This is a valid concern. Post Type always beats Author when queried object is being determined. As such, we should avoid this notice by not trying to set author name as the title when we are in fact on a post type archive screen. The fact that author is in the path is meaningless as to precedence.

[wonderboymusic]

In 28251:

Set the proper value for wp_title() when is_author() and is_post_type_archive() are both true. post_type should always win due to the precedence indicated in get_queried_object().

Props mordauk.
Fixes #25398.

[mordauk]

Excellent, thanks so much @wonderboymusic!