wpdb::$base_prefix is not documented

[hakre]

Probably wpdb::$base_prefix has been merged into from MU and not further specified then.

It genereally can be replaced with wpdb::get_blog_prefix(0) when the MULTISITE constant is defined. That is are after wp-settings.php has been included (wp-config.php, wp-load.php), even on SHORTINIT.

It might be that this function call does not cover all cases needed because if MULTISITE is not defined when called, it will not return the wpdb::$base_prefix.

More insight into MU is needed, feedback appreceated. Some places look like that they are not aware of the wpdb::get_blog_prefix() function. Probably legacy MU code.

Related: #16756

[hakre]

I'm a bit unsure for the first change in user.php, the second and the other two files look good to me.

[hakre]

Related: #16764

[jdgrimes]

+1 to this. I think we should introduce a wpdb::get_base_prefix() function instead of relying on wpdb::get_blog_prefix( 0 ). That maybe belongs on a separate ticket though.

[SergeyBiryukov]

#26887 was marked as a duplicate.

[SergeyBiryukov]

#26887 was marked for 3.9, let's move the patch from there.

[pento]

attachment:16762.diff​ is a copy of attachment:26887.diff:ticket:26887​.

[DavidAnderson]

Responding to the original report: using wpdb::get_blog_prefix(0) as an alternative to $wpdb->base_prefix is wrong, for the reason given in the original report: "It might be that this function call does not cover all cases needed because if MULTISITE is not defined when called, it will not return the wpdb::$base_prefix."

The "might" can happen, on sites that have been upgraded from old pre-3.0 WPMU setups. In that situation, wpdb::get_blog_prefix(0) returns junk data, because MULTISITE is indeed not set and is_multisite() is still true. I have seen this happen in the wild. Despite the apparent intention inside the code of wpdb::get_blog_prefix(), in fact wpdb::get_blog_prefix(0) is not useful unless you first know that you're not on such a site, and if you are, only wpdb::$base_prefix is useful.

Therefore, the simpler patch that Pento has added in 16762.diff should be used, and the original patch should not. It is better to just make clear that wpdb::$base_prefix is the way to go, by making it explicitly public.

[nacin]

In 27249:

Declare $wpdb->base_prefix.

props DavidAnderson.
fixes #16762.