tax_query clobbers tag and category

[wonderboymusic]

The main query should return a tag or category as its queried object if tax_query is applied to a tag or category archive page. It currently returns the first term derived from the WP_Query->tax_query->queries array which does not include the tag or category as a term in the request. WP_Query->tax_query->queries is a portion of the request, but not the request. Because WP_Query sets is_tag and is_category flags, they have to be captured before dealing with is_tax

The result of this bug is that theme functions return the wrong data because the wrong term is returned with get_queried_object.

Real world example: at eMusic, we pass regions into pre_get_posts to regionalize the content that is returned. On a tag page, if you are in the US, we pass the regions "ALL" and "US" to make sure you are looking at appropriate content. Here's what the title for the archives looks like - (spoiler: It's "ALL" when it should be "Daily Download"):

​http://www.emusic.com/17dots/topics/daily-download/

I am attaching a patch.

[wonderboymusic]

Patch for WP_Query->get_queried_object

[scribu]

I'm not sure using $this->get( 'cat' ) is much better: you can have ?cat=1,2,-3.

[wonderboymusic]

Replying to scribu:

I'm not sure using $this->get( 'cat' ) is much better: you can have ?cat=1,2,-3.

It works, if you have a URL like so: www.emusic.com/17dots/topics/daily-download/?cat=1,2,3,4

• is_tag is true
• is_category is true
• cat returns 1 (the first category id)
• tag_id returns 8376, which is correct

The public query is correct:

array(2) {
    'cat' =>
    string(7) "1,2,3,4"
    'tag' =>
    string(14) "daily-download"
}

is_tag takes precedence over is_category and should

[wonderboymusic]

can I get a 3.5 amen from the congregation? tax_query has been breaking theme functions for a while now

[markoheijnen]

I really don't see the issue. If you handle category or post_tag as a custom taxonomy you wouldn't have the issue right?
I rather go for something like that then adding code for only category or post_tag

[wonderboymusic]

The fact that we are already doing this:

if ( $this->is_category || $this->is_tag || $this->is_tax ) {
    ....
}

...means we need to check them before arbitrarily grabbing the first term in the stack

[wonderboymusic]

Patch still applies, this was a really annoying issue I had to work around in multiple places

[wonderboymusic]

Added unit tests to cover tag / category pages with a tax_query injection - tag / category should be the queried object. Related: #5358.

[nacin]

Unfortunately it's too late for this, but let's do it in early 3.8.

[wonderboymusic]

Added a new patch, gonna let this stew for a lil bit - I think WP_UnitTestCase::go_to() is doing something weird. Some of my assertions that I was trying were returning is_home() === true for a custom taxonomy, which means some other unit tests might be returning false positives. Will inwestigate.

[wonderboymusic]

In 26006:

WP_UnitTestCase::go_to() tried its best to clean up global space, but ultimately fell short. Because it was blowing away WP every time it was called, it was dropping all the query vars that were registered for custom taxonomies and custom post types (ouch).

Introduces _cleanup_query_vars(). This is a prerequisite for the unit tests on #20767. All unit tests pass with this change.

See #20767.
Fixes #25818.

[wonderboymusic]

In 26007:

Category and tag are typically checked before checking for a custom taxonomy. If the global query matches category or tag (even if it also has tax_query set), return category/tag as the queried object, instead of arbitrarily returning the first term in the tax_query stack (typically those added with 'pre_get_posts').

Real world example: ​http://www.emusic.com/17dots/topics/daily-download/ - "tag" page, regionalized for US-only content using pre_get_posts passing in the terms "US" and "ALL" for "region" (custom tax). All of the theme functions would output "ALL" as the term name. Even though it was a tag archive, the queried object was an arbitrary term from tax_query.

See [26006]. All unit tests pass.
Fixes #20767.

[Otto42]

This appears to have caused a regression issue. Related: #26627

[Otto42]

Specifically, on a default install with pretty permalinks, when you visit /category/uncategorized, then the 'cat' variable is not set.

Instead, the category_name is 'uncategorized', and there is a tax_query with
'category' as the taxonomy and 'uncategorized' as the term. You cannot only use get('cat') here. This probably breaks tags in a similar way for the same reasons.

[lkraav]

Yep, what @Otto42 said. This is breaking at least a few of my customers sites pretty bad. Moving over to #26627.