Blogging Software

It started innocently enough, but as usual turned into yak shaving rather quickly. I wanted to try out some graphical editors for posting to my blog. Sounds simple enough. Except that a while back, I chose wordpress-pg. Its a version of wordpress, but it talks to PostgreSQL instead. Except that for some reason, my copy doesn’t have the xmlrpc.php file needed. So heading over to the wordpress-pg site, I am greeted by this lovely message.

WARNING! This version is probably subject to flaws in xmlrpc handling. Delete xmlrpc.php if present in your install. This flaw can allows outside attackers to execute arbitrary commands as the user your web server runs as.

Oh dear. So I won’t be doing that then. But part of the problem is that it’s already fixed in wordpress 1.5 (MySQL edition). Sadly, wordpress-pg is a very inactive project. I know, it’s open source, fix it yourself. But right now, I more or less just want something to work. And I don’t want to delve into scary php if I can help it (I know, that’s rich coming from a Perl programmer). So what are the choices?

I could look at getting MySQL installed and moving over to wordpress proper. Well, I’ve finally gotten around to doing some MySQL at work and I now understand it a little bit, even if I don’t like it that much. But I still have to get the actual database ported from PostgreSQL to MySQL somehow, which seems jolly arduous.

The alternative is to take a look at Typo, a Rails powered blogging engine. The selling points are that it appears to be actively maintained, it’s written in Rails (which I wish to play with) and also that it has a wordpress import script. So I’ve just spent an hour attempting to convert my wordpress-pg install over to typo. And I have to say that it works pretty well. Here’s what I found.

Firstly, I followed the basic install to get typo up and running. I saw Piers complaining about it, but it’s reasonable for me. But I’ve used rails before, so I’m probably not the target market. Anyway, I got to the admin screens and set up a test account pretty quickly. I then ran the import script giving it my old wordpress database name. Needless to say, it didn’t work first time. I had to make these changes to the script:

  1. Get rid of all backquotes, that’s some weird MySQLism.
  2. I had to change all entry['ID'] to entry['id']. PostgreSQL downcases things.
  3. I had to rework the trackback support slightly. Because wordpress-pg is based on wordpress 1.2, trackbacks are stored as a comment that starts with <trackback /> at the beginning. So I had to change comment_type = 'trackback' into comment_content LIKE '<trackback />%'
  4. The import script runs in the dev environment by default, but I had been testing in the production environment. This meant I had no users set up in my dev environment. Consequently, I had to patch up the relationships between the users and the articles afterwards (update articles set user_id=1;). Actually, looking at the script, it doesn’t seem to make those links anyway…

The biggest problem was actually getting the script to access the original data. The script assumes that you can do the MySQLish thing of accessing another database by specifying dbname.table. This doesn’t work in PostgreSQL. But, you can take advantage of the fact that PostgreSQL does support schemas, so instead, you can create a schema called wordpress and load a dump of the main database into there. I had to make a few edits to the dumpfile before loading it in though.

  1. Get rid of the stuff about plpgsql at the top. I don’t use it.
  2. Add CREATE SCHEMA wordpress and SET search_path = wordpress, public, pg_catalog.
  3. Comment out all the ALTER foo SET OWNER TO wordpress lines. You have to import it as the typo user and don’t want that changing behind your back.

After the import you can just run DROP SCHEMA wordpress CASCADE to clean up.

After that, I now have a working blog with all my old content. Hurrah! Not simple, but not too difficult either.

Now before I get this main blog converted over, I just need to work out how to run FastCGI scripts from Apache, something I haven’t done before. And then I’ll be away, and I can uninstall wordpress-pg.

2 Comments to Blogging Software

  1. I guess that I got lucky with the install. Because I’d already been playing with Rails, I had all the prerequisites already installed, and a rough understanding of how to configure a rails app.

    But the conversion script was really useful. I’m just very pleasantly surprised at how easy it was to hack on. Definitely a plus point for Ruby.

  2. Piers Cawley says:

    Thanks for the feedback on this; data portability is one of the things we really need to get right if we want people to switch to Typo.

    That blog entry of mine was based on feedback from someone who had entered the Typo theming competition and from experience of the kind of questions we keep getting in the #typo IRC channel.