New Conditional Template Tag: is_multi_author()

[iandstewart]

With the popularity of publicly-released magazine themes it'd be great if themers had an easy way to check for the existence of multiple published authors on a blog.

It'd be useful for single author blogs as well--themers can hide author names and links when there is only 1 published author.

[filosofo]

I don't understand all the extra logic that you have there, the results of which don't seem to be used.

Can't you just do something like the following?

function is_multi_author() {
   global $wpdb;
   return (bool) ( 1 < $wpdb->get_var("SELECT COUNT(DISTINCT(post_author)) FROM $wpdb->posts WHERE post_type = 'post' AND " . get_private_posts_cap_sql( 'post' ) );
}

[iandstewart]

Indeed. That was a hacked up wp_list_authors. I'll attach your (far more elegant) version, filosofo.

[wpmuguru]

Why not keep track of the multi_author status via the save_post hook?

If the proposed version was implemented and used in a theme it would add a database query to every pageload.

[lancewillett]

+1 for the idea, love that it will solve the problem of single-author sites and not wanting the redundant author name and link on each post.

Replying to wpmuguru:

Why not keep track of the multi_author status via the save_post hook?

How would you suggest keeping track of the value? Even if it was stored as an option or meta value somewhere it'd still require a database query to get that value, too, right?

[nacin]

Realistically it could be an autoloaded boolean option.

[nacin]

Posted this on wpdevel, ​http://wpdevel.wordpress.com/2010/08/30/at-this-weeks-dev-chat-well-start-t/#comment-10095.

Would be dirt cheap to store it in an autoloaded option that stores either 0 or 1, and we can toggle it based on user creation. This probably can also assist in our other instances where we don’t show author drop-downs in the admin area based on the number of non-subscriber users.

Wouldn't you know I had the same idea five weeks ago, as the previous comment? :)

[nacin]

On user creation, or on post creation. Probably a combination of both (and role changes).

[westi]

I don't think this should care about private posts.

Just is more than one author with published posts.

[westi]

Check for multi author and wp cache the result, clear on any post transition

[westi]

Simple patch with caching.

Clears on post transitions.

Could use a transient instead but this feels like something that should cache for as long as possible if we have a cache and fall back on the query otherwise as it isn't too slow anyway.

[nacin]

We can use the publish_post hook instead. This will add an extra query to basically any site that doesn't use a persistent cache. While I like that we can leverage the idea of having a persistent cache for many situations, this seems like a good case IMO for just a flag that gets updated on publish_post.

[westi]

Replying to nacin:

We can use the publish_post hook instead. This will add an extra query to basically any site that doesn't use a persistent cache. While I like that we can leverage the idea of having a persistent cache for many situations, this seems like a good case IMO for just a flag that gets updated on publish_post.

Only sites that use the function.

And the query is super fast anyways

[filosofo]

Rather than

SELECT COUNT( DISTINCT post_author )  FROM $wpdb->posts

how about instead

SELECT DISTINCT post_author FROM $wpdb->posts ... LIMIT 2

Since we only need 2 distinct authors to be multi-author, we can let the db engine stop once it's found 2 authors: it considers only the number of table rows it has to traverse to before finding 2 authors. In contrast, the former query actually considers all rows, according to EXPLAIN results.

Please see patch.

[westi]

Replying to filosofo:

Rather than

SELECT COUNT( DISTINCT post_author )  FROM $wpdb->posts

how about instead

SELECT DISTINCT post_author FROM $wpdb->posts ... LIMIT 2

Since we only need 2 distinct authors to be multi-author, we can let the db engine stop once it's found 2 authors: it considers only the number of table rows it has to traverse to before finding 2 authors. In contrast, the former query actually considers all rows, according to EXPLAIN results.

Please see patch.

Great thinking outside the box optimisation.

Thank you!

[filosofo]

is_multi_author_cached.3.14405.diff responds to my realization that the cache check wasn't going to work properly without checking the type: cache an integer to distinguish single-author (int) 0 from invalid cache (bool) false.

[scribu]

We should use get_posts() here, so that we can set 'post_type' => 'any'. Would need #14777

[westi]

Replying to scribu:

We should use get_posts() here, so that we can set 'post_type' => 'any'. Would need #14777

The demand for this is very Post specific though rather than CPT?

[nacin]

Replying to westi:

The demand for this is very Post specific though rather than CPT?

Agreed, that's why I didn't suggest it. Published posts seems fine.

[scribu]

Ok, but we should still use get_posts(), with no caching etc.

[markjaquith]

Punt.

[iandstewart]

Is there a chance of this making 3.2? I'd love to have it available for the Twenty Eleven theme.

[lancewillett]

+1 for getting this in 3.2.

One of our biggest requests on WP.com is for a way to enable group blogs to show author information (or turn it off for one-person blogs).

[nacin]

I'm still not a fan of the patches here. Still feels to me like relying on persistent caching is kind of lame. But I can go for it.

[scribu]

Well, the other solution would be to have the user flip the switch manually, either through an admin option (gasp!) or through some code in functions.php.

[wpmuguru]

Replying to nacin:

I'm still not a fan of the patches here. Still feels to me like relying on persistent caching is kind of lame.

Same here. It's about the same amount of code to do this via an option in the options table.

[westi]

Replying to wpmuguru:

Replying to nacin:

I'm still not a fan of the patches here. Still feels to me like relying on persistent caching is kind of lame.

Same here. It's about the same amount of code to do this via an option in the options table.

But it's not an option.

Maybe we should use a transient instead of directly caching so we get the benefit of the temporary persistence from that.

[wpmuguru]

Replying to westi:

Maybe we should use a transient instead of directly caching so we get the benefit of the temporary persistence from that.

Sounds like a decent compromise.

[wpmuguru]

use a transient instead of persistent cache

[westi]

"is_multi_author_cached.3.14405.diff" uses a nice fast query and the object cache (if it exists)

This means that for sites with an object cache it can be used to avoid queries

For sites without they just get one fast query - better than using a transient which means two queries one to check the timeout and one to fetch the value.

[nacin]

Go for it.

[westi]

In [17901]:

Introduce new is_multi_author() template tag to make it easier for themes to have different behaviour when a site has more than one
author. Fixes #14405 props filosofo.