Python, Web Applications

Django in 24 hours

Last Saturday afternoon I decided to learn Django. It was 2pm on the first day of SiCamp 2008 in London and being the only developer in the room at that point I decided that I should do whatever I felt would be the best option to get an application running by 2pm the next day.

Previously I have done some Google App Engine and the experience convinced me to give Django a go after I found myself, by intuition, creating a GAE project structure of handlers.py (views), models.py and a directory called templates that contained templates. I was then disappointed to find the whole world had got there before me.

So, Django in 24 hours, baptism of fire. What do I think now looking back on the experience?

Everyone has told me that the Django documentation is good and I think I have to concur. Not everything is so clear that when you’re speed reading in one window and typing in another it works first time but importantly nothing in the documentation is actually wrong. When stuff is not working a second, careful look at the documentation got me back on track.

Importantly Django’s core model of web development is sound and intuitive. My editor had around ten files open for the project and the flow of adding something to the application did naturally flow from url to handler to view to model. Maybe the only quibble I have is that the views.py file is deceptively named in MVC terms.

The core of the framework is amazingly concise, I spent the majority of my time thinking about the problem not about the framework API. Binding a URL to function made sense, having to specify a template instead of having one inferred from the method name was maybe my one criticism in the method handler but on the plus side it does allow for flexibility in handling requests. Handing off from one request handler to another was very easy.

Django templates are both amazing and annoying. The syntax and principles are amazing, it was easy to play around with the pages and the template inheritance was really powerful for avoiding duplication. However when I transferred the application from self-serving to mod_python the template generation was very wobbly when compiling changes from the file system. Of course this could also have been mod_python but it was the latest 3 series stable source compiled for the machine. I’ve used Jinja2 previously when generating HTML in Python and might be tempted to stick with it in future.

Django models are great, I hate ORM but I really liked syntax for defining persistence properties and I liked the way that you don’t have the fact that you are really dealing with SQL hidden away from you. It genuinely seemed a more convenient way of expressing the data model rather than an OO wallpaper over relational data storage. I didn’t feel the need to add domain logic to the models but I felt like it wasn’t really polluting the model to do that either.

One thing that didn’t work at all was changing the relations between models; it took me two or three attempts to finally model the relationships between the data concepts. Each time I changed a Foreign Key or Many to Many relationship I ended up deleting the database (SQLite3) as I couldn’t figure how to migrate from the old schema to the new.

One reason for choosing Django was the idea that I wouldn’t have to write the backend code as the admin stuff would be right there for me. It took me a while to get the 1.0 admin to fire up but once it was running it did perform as advertised. One of the attractive things about the application was that the data model followed the conceptual language of the solution in a really powerful way. You could use the admin interface to have a Devotee perform Devotion to an Action. My geek excitement peaked anyway, YMMV.

So them’s the highlights of the experience. Overall Django delivered me a rapid web development process in an intuitive, powerful way and lived up to nearly all of the claims made on the tin. Deploying to Apache/mod_python was painful but most of the pain surrounded the infrastructure of my box (multiple versions of Python, Apache config files) and my lack of mad Apache admin skillz.

I would happily tackle another project in it again.

Perhaps of interest is how the Django development experience matches up against Rails or GAE  which would have been the other obvious choices. GAE would have been very similar but the deployment would have been better and I wouldn’t have had any automatic admin. In retrospect it may have been a better choice for a hack party type event. It certainly would have been my choice for personal projects for easy of deployment but now I have one Django app running perhaps that isn’t as relevant any more. Certainly the thing that has kept me from GAE before, the pain of data migration, doesn’t seem that better in Django (except that you control the datastore and its contents).

Compared to Rails?

  • Admin is much more awesome than scaffolding.
  • Django ORM is much less complex than Active Record, all the data required to create, deploy and use the object is in one place. Django doesn’t have Migrations but has its own brand of database versioning pain.
  • RSpec is awesome (despite its monkey patching of Object) so you aren’t going to beat Rails for easy testing.
  • Django templates are more powerful and easier to use than Erb but you have a lot of Ruby templating options so it’s hard to make a complete comparision. They probably both similar in the sense that you can find a template library that suits your preferences. Django is the purely solution out of the box.
  • Routing and Controllers are much less involved in Django than Rails.
  • Django is less opinionated about how you structure your application directories, which I like.
  • Django doesn’t bake-in AJAX components but is “batteries included”, Rails probably generates better Web2.0 style apps for less effort.
  • Finally Django uses only a few code generators because its basic structure is far less involved. It also generates far less “stuff” for each MVC element which I quite like as I don’t tend to use everything Rails generates.

Okay detailed analysis over, what’s the high-level view? Django and Rails are similar experiences but I think the major differences between them are almost what you could say about Python and Ruby. In Django you are going to get simplicity, clarity and a real choice of how you plug your infrastructure components together. In Rails you are going to get magic up front which is cool but also magic at the back end, which is not cool. Ultimately I think the answer is how opinionated you like your software. Well punk? How opinionated do you like it?

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4 thoughts on “Django in 24 hours

  1. RaiulBaztepo says:

    Hello!
    Very Interesting post! Thank you for such interesting resource!
    PS: Sorry for my bad english, I’v just started to learn this language 😉
    See you!
    Your, Raiul Baztepo

  2. Hi !!!! ^_^
    My name is Piter Kokoniz. oOnly want to tell, that I’v found your blog very interesting
    And want to ask you: what was the reasson for you to start this blog?
    Sorry for my bad english:)
    Thank you:)
    Piter.

    • Initially it was to record stuff I had learned so that I could refer back to it again later. I would end up Googling back to the blog.

      Over time it’s become much more about technology and the “day job”, since I’ve become a consultant the blog tends to be read by clients and potential clients so I can’t do anything to wacky in it.

      If see any celebs though, they are still going here.

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