June 17, 2010

404 words 2 mins read

Serendipity to WordPress – Changing table prefix

While this isn’t strictly part of the migration process from S9y to WordPress, I decided to take some advice I read on the net and change the prefix for WordPress tables.  Most use this feature for when they have to share a database, but the suggestions I read said to do it to help prevent from SQL injection hacks.  Basically the majority of these injections presume a default of ‘wp_’ prefix.

I made this after install very simple by going in MySQL and running

RENAME TABLE `wp_posts` TO `prefix_posts` against each table (where “prefix_” was the new prefix).  After changing it in MySQL, I changed the wp-config.php line of _$table_prefix  = ‘wp_’;_ to read as my new prefix.  I popped up to the web and the blog worked fine.  Except… I couldn’t access the administrative interface.

You do not have sufficient permissions to access this page.

LIAR!!! What the hell? Yes I do.  I did 10 minutes ago and I should now.  I tried my other (administrative) users, same problem.  This was quite displeasing to me. After a little googling about, I found out that the answer is that the `meta_key` prefix of ‘wp_’ (in `wp_usermeta`) and certain values in `wp_options` are also dependent of this prefix value.  Fortunately it is really easy to fix:

  • UPDATE `<strong>PREFIX</strong>_usermeta` SET `meta_key` = REPLACE( `meta_key` , 'wp_', '<strong>PREFIX</strong>_' );  -- Change <strong>PREFIX</strong>_ to your new prefix.
  • UPDATE `<strong>PREFIX</strong>_options` SET `option_name` = '<strong>PREFIX</strong>_user_roles' WHERE `option_name` = 'wp_user_roles' AND `blog_id` = 0; -- Change <strong>PREFIX</strong>_ to your new prefix.

Execute those two lines of SQL (after you’ve replaced it with the proper prefix), and you’ll be ready to rock and roll again.  This is one of those odd little bits that they don’t explain anywhere in the manual – probably because most people don’t use anything other than the defaults… which brings us right back to the security concern (i.e. easy to guess/default password = bad).

Having keys in tables change because the table prefix is different is one of the stranger things done in a web application that I’ve worked with.  I can’t really think of a reason to do this, but I’m sure the developers had a good reason (as strange as it might be).  Fortunately this problem is easy enough to fix, but it certainly is frustrating when your admin user gets “You do not have sufficient permissions to access this page.” and you know better.

access denied MySQL s9y serendipity wordpress

Serendipity to WordPress – Post import

June 11, 2010

The first thing you need to do in migrating from Serendipity to WordPress, is to move the post content. Luckily for all of us, at some point in time an importer was written (and shared). It has floated around the internet for a while and been updated a number of times. The version I used was verison 1.3, last updated by a German fellow. While his updates were good, I needed a little more out of it. Two pieces that were lacking were the handling of drafts vs published posts (John and I have a number of drafts, as has been previously mentioned) and the most important, matching up post id numbers. Without that one piece, you can’t move between the two platforms and maintain any links.

Serendipity to WordPress – Rewriting URLs

June 14, 2010

So the second most important thing to for a S9Y to WordPress migration, after you import the posts, is to make sure as many of the old links work as possible. It doesn’t actually require all that much work to get 90% of the old links working. With Apache &amp; mod_rewrite you can be up and running in just a few minutes. The example below is what I’m actually using and should cover most everything if you were using the /archives/1234-Post-name-here.html format (in S9y). The only reason it requires so many rules and doesn’t cover all the links is because S9y is REALLY BAD about cleaning up the URLs. It basically has no internal mechanism for redirecting people to the proper final name.

Houston, We have WordPress

June 9, 2010

If you are seeing this, you probably realize things look a bit different around the blog. Not terribly different, but different none the less. It is slightly more than changing the theme this time, though I managed to find one that was close to what it previously was. Today’s change is slightly bigger. We’re running WordPress 3.0 (RC).