Spawning Django Blogs

Mon 18 October 2010 by Jim Purbrick

Since leaving Linden Lab I have been talking to a number of people about doing freelance consulting and development work while I get my start-up off the ground and last week got round to setting up a UK limited company so that people will actually be able to pay me.

Setting up a company is insanely easy these days: if you go to companies made simple it will cost you less than £17 and 10 minutes of form filling. Coming up with a name is harder, but within a couple of hours I found that 18dex was available as a .com TLD, twitter account and facebook username. Meaningful 5 character .coms are pretty tricky to come by these days, so I snapped it up and 18 Dexterity Ltd. was born — a pretty fantastically geeky name for an agile software engineering company I hope you’ll agree.

A few minutes later I had a holding page up for 18dex.com, but it looked pretty sad with no content, so I started thinking about setting it up as a blog. I have a stack of relevant software engineering posts on jimpurbrick.com from the last few years, but they are sandwiched between less relevant posts on 100robots, Second Life and various miscellany. I didn’t want to move the software engineering posts from jimpurbrick.com as they’re part of what I do and regularly updating a single blog is quite enough work. I also didn’t want to copy the posts from one blog to another as it would potentially end up with 2 independent comment threads on each blog. There would be no definitive version of a post, a blatant violation of Don’t Repeat Yourself.

Luckily Django includes a piece of machinery to deal with this problem in its sites framework, something I’ve been meaning to have a closer look at for some time. The sites machinery simply lets you associate a piece of content with a site and keeps track of the current site, allowing you to filter the content in the database to only show a subset on each site.

While the byteflow blog engine I use for jimpurbrick.com supports the sites framework, each post is associated with a single site via a ForeignKey. In order to allow posts to be shown on both jimpurbrick.com and 18dex.com I had to change that ForeignKey field to be a ManyToManyField: a single line change in the python code, but something that requires a little wrangling to massage the existing data to fit the new model.

I’ve been using the excellent South in all my recent projects to allow me to easily migrate data across django model changes. Although jimpurbrick.com dates from long before South was available I managed to convince south to manage the migration by dumping the blog_post table to json, dropping the table and recreating it with south, reloading the data and then letting south migrate the data to the new ManyToMany schema. While this was slightly more fiddly than it could have been it means that the blog app is now being managed by south, which will make future development on the blogs much easier.

Once I had migrated the data to the new model and associated the software engineering posts in jimpurbrick.com with both sites in the django admin interface all that remained was for me to clone the jimpurbrick.com directory with mercurial to create an 18dex.com directory and choose and tweak a byteflow theme for the new site.

Once again I’ve been very impressed with Django and Byteflow, which have proven to be incredibly powerful tools that are very easy to work with. In a few hours I was able to create professional and personal views on to my blogging which can be easily administered from a single interface and allow comment threads and users to easily flow between them. If you’re just interested in my software engineering posts, head over to 18dex.com, if you want to hear about music, Second Life and everything else I get up to, stay subscribed to jimpurbrick.com. If you notice anything broken on either blog, then please leave a comment to let me know.


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