WPMU DEV Community » Topic: Guide that explains how to convert a regular WP plugin to a WPMU plugin.

drmike on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

drmike — Tue, 17 Nov 2009 19:25:40 +0000

Heck, I hardcode the prefix. I'm lazy. :)

Plus it's one less function call. And I know all of my installs use the prefix. (Except for one and they use wpmu_)

Andrew on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

Andrew — Tue, 17 Nov 2009 17:00:32 +0000

I think what they did in that case was by accident. It looked like they had thr prefix hardcoded at one point and then decided to add the prefix variable. The problem is that they forgot to remove the hardcoded prefix.

Thanks,
Andrew

mikee17 on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

mikee17 — Tue, 17 Nov 2009 08:38:51 +0000

As Aaron said: "SQL should also not hardcode the wp_ prefix on table names."

I would like to add: Apart from using wp_prefix($wpdb->prefix), do NOT use wp_ in-between the tablename, eg: use $table_name = $wpdb->prefix . "eCart_tbl"; and NOT $table_name = $wpdb->prefix . "wp_eCart_tbl";

Thanks & Regards

Aaron on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

Aaron — Fri, 30 Oct 2009 14:05:33 +0000

Occasionally a plugin doesn't use the Wordpress $wpdb class for database actions. That's a no no and will break in Multidb and usually MU too.

SQL should also not hardcode the wp_ prefix on table names.

mikee17 on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

mikee17 — Fri, 30 Oct 2009 09:04:54 +0000

One more thought that just stuck....we must also need to consider multi-db functionalities(when its a db dependent one) when a plugin is made/modified or does the wp normal stuff handles it?

Thanks & Regards

mikee17 on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

mikee17 — Fri, 30 Oct 2009 08:56:33 +0000

@Barry, Thanks! There are quite a few plugins that we tried...some were successful, other were NOT and still not. :) What you have mentioned are indeed 100% right.

@drmike, Thanks! Thought if there is some general check points, specific functions that we need to handle so on...I thought it would help all if we put them together here.

@Aaron, Thanks too. Thats a real point we should be aware of....some paid versions of plugins come encrypted too...cant even check if it does have any such security hole.

Yes, if more 'n more people put their thoughts here...we are likely to get more exposed to what all need to at-least kept in mind in such situations.

Thanks & Regards

Aaron on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

Aaron — Thu, 29 Oct 2009 15:01:29 +0000

Also you need to be VERY aware about the security holes many normal WP plugins will open in your site. Almost none of them verify/filter user input. They can open your entire site to XSS and SQL injection vulnerabilities.

Filter input/filter output.

drmike on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

drmike — Thu, 29 Oct 2009 14:48:12 +0000

Hardcoding locations.

Hardcoding the wrong locations....

Our method of testing is to install it on a testbed, give it a shot and see what happens and what errors are produced. You have to remember that even though that there are guides on how to build a plugin, even a general one, few developers follow it word for word. And then you have all the name changes of the functions over the versions, different functions that do the same thing, etc. It really is a mess although to be honest, most open source platforms are.

A lot of the plugins have been discussed previously either here or on the regular mu forums. If you;re having a specific problem with a specific plugin, may want to check to see if it;s been discussed previously.

Barry on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

Barry — Thu, 29 Oct 2009 13:44:09 +0000

I haven't seen one, but it all depends on the plugin in question (is it your own or are you trying to fix one).

Some plugins have easy fixes, but a few (mentioning no names) are a nightmare and just need to be scrapped and re-written, or aren't worth the bother.

A few things to look out for:
Hardcoding database prefix
Creating tables (and forms based on them) but not passing or storing the blog_id / user_id for filtering
Hardcoding locations.
Relying of activation hooks to set up tables (mu-plugins don't fire this).

mikee17 on "Guide that explains how to convert a regular WP plugin to a WPMU plugin."

mikee17 — Thu, 29 Oct 2009 11:54:55 +0000

Hi,

Has anybody seen a good step by step guide that explains how to convert a regular WP plugin to a WPMU plugin?

I do understand it can vary from plugin to plugin as some create tables and some do not.
And several other parameters that determine this....

Can we put all of them together here?

Thanks & Regards