Consider a doing_it_wrong call for query_posts()

[johnbillion]

The query_posts() function affects the main query, so things (like template conditionals) can break if plugins or themes use it without calling wp_reset_query() immediately afterwards.

Unless there is a situation I haven't considered, query_posts() shouldn't be used at all on requests where the main query is run (query_posts() of course has a use in situations like AJAX calls when the main query isn't run).

• For secondary loops, get_posts() or the WP_Query() class should be used.
• To modify the main query, there are hooks all over the place, such as 'request', 'parse_request', 'parse_query', and 'pre_get_posts', in addition to the SQL filters such as 'posts_where', 'posts_join', etc.

Maybe doing_it_wrong() should be called if query_posts() is used after the main query is run, with pointers toward a relevant Codex article on secondary loops or filtering the main loop.

[johnbillion]

kovshenin just released a plugin for this: ​http://wordpress.org/plugins/stop-query-posts/

[wonderboymusic]

I am going to suggest close on this - there are a lot of people who haven't seen @nacin's talk and don't know it is evil. For instance, Dealbook uses query_posts() 4 times on the homepage. Would I like to refactor all of that code? YES, but it is not in the cards for me to do so right now. I'd rather the logs not be flooded.

[markoheijnen]

Why not just deprecate it? We hate it and we think people shouldn't not use it. So why keeping it?

[johnbillion]

Replying to wonderboymusic:

there are a lot of people who haven't seen @nacin's talk and don't know it is evil. For instance, Dealbook uses query_posts() 4 times on the homepage.

That's the entire reason for adding the doing_it_wrong() call...

[nacin]

Replying to markoheijnen:

Why not just deprecate it? We hate it and we think people shouldn't not use it. So why keeping it?

Because it is really easy to use and the alternatives are tougher to articulate and code, especially to people just hacking together a theme.

Re-opening for consideration down the line. I've been thinking about a new pre_main_query hook that parallels pre_get_posts but only runs $query->is_main_query() and ! $query->is_admin(). That might take some of the magic out of using pre_get_posts.

[rmccue]

Replying to nacin:

Because it is really easy to use and the alternatives are tougher to articulate and code, especially to people just hacking together a theme.

Re-opening for consideration down the line. I've been thinking about a new pre_main_query hook that parallels pre_get_posts but only runs $query->is_main_query() and ! $query->is_admin(). That might take some of the magic out of using pre_get_posts.

Along those lines, maybe we could have something like:

function wp_modify_query($args) {
    add_filter('pre_get_posts', function ($query) use ($args) {
        return array_merge($query, $args);
    });
}

(Obviously with 5.2 syntax, this is just for demonstration)

This would work similarly to how we do admin menu items by hiding the fact that we have a filter at all, which might be a bit easier for themers to use than the hook, and they can use this directly in their functions.php. (And maybe a corollary function as wp_modify_main_query.) Just a thought if we do want to push away from query_posts() but still keep it simple for themers.

[SergeyBiryukov]

Replying to rmccue:

Along those lines, maybe we could have something like:

function wp_modify_query($args) {
    add_filter('pre_get_posts', function ($query) use ($args) {
        return array_merge($query, $args);
    });
}

(Obviously with 5.2 syntax, this is just for demonstration)

Looks like this function would have a very limited use, since there's no way to use conditional tags with it.

[SergeyBiryukov]

Replying to nacin:

I've been thinking about a new pre_main_query hook that parallels pre_get_posts but only runs $query->is_main_query() and ! $query->is_admin(). That might take some of the magic out of using pre_get_posts.

Let's do this.

Attached a patch for consideration. The docs might need some work, I've just copied them from pre_get_posts.

[SergeyBiryukov]

#36874 was marked as a duplicate.

[johnbillion]

Closing due to lack of movement. As much as I'd like to trigger a doing_it_wrong in query_posts(), Scott's point stands that it'll add noise to logs.

Sergey's patch can be considered in a new ticket if there's interest, but it doesn't do anything that can't already be achieved in pre_get_posts.