What is Django?

The Django Web site describes Django as "a high-level Python Web framework that encourages rapid development and clean, pragmatic design." Basically, Django is just about the most amazing thing for Web development. I have tinkered with several different Web technologies, but nothing seems to even come close to what Django can do for me.

What is Python?

Python is a programming language used in numerous aspects of computing these days. It has a very simple yet powerful syntax. It's an easy language for beginners to pick up, but it provides adequate levels of power for the more experienced developers out there. If you have never programmed anything before, or you have dabbled with something like BASIC, Python should be fairly straightforward. If you are a programming veteran, but have only worked with languages like C, C++, Java, etc, you might struggle a bit with the syntax of the language. It's not difficult to overcome the differences in a couple hours of hands-on development.

Let's get started.

Installing Python...

Having Python installed is critical--Django does not work without Python. I'm guessing that you're relatively familiar with the procedures for installing software packages on your particular operating system. However, I will share a few notes to point you in the proper direction if you're lost. If nothing else, just head over to the Python download page to download anything you need to install Python. I whole-heartedly recommend using the latest stable version of Python for Django, but you should be able to get by with as early a version as 2.3.

Setting Up Your PYTHONPATH...

Generally speaking, if you didn't have Python installed before starting this tutorial, you will need to setup your PYTHONPATH environment variable. This is a variable that lets Python know where to find useful things (like Django).

export PYTHONPATH=/usr/lib/python2.5/site-packages:$PYTHONPATH

source ~/.bash_rc

Installing Django

Once you have Python and have verified that you have version 2.3 or later, you are ready to install Django. Currently, the latest stable release is 0.96.1, but this is grossly out-dated. Django 1.0 will be released on September 2nd 2008, so the "unstable" copy of Django is pretty close to what 1.0 will have to offer. There are some incredibly useful improvements in the unstable version that I don't think I could do without anymore, so that's what I'll talk about installing here.

First, you need to have a subversion client. On Windows, the most popular one is called TortoiseSVN. On Mac OS X, I have played with a few, but I think Versions is a pretty decent one. Linux also has several to choose from, but if you're using Linux, you're probably going to use the command line anyway (right?).

For brevity, I will just use the subversion commands necessary to accomplish this task (instead of discussing all GUI interfaces to subversion).

The exact location that Django should be installed differs from system to system, but here are some guidelines for typical setups:

• Windows: C:\Python25\Lib\site-packages
• Linux: /usr/lib/python2.5/site-packages
• Mac OS X: /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages

If you want a definite location, run the following command:

python -c "from distutils.sysconfig import get_python_lib; print get_python_lib()"

Once you know that location, go there in your command prompt or terminal session. Then execute this command svn co http://code.djangoproject.com/svn/django/trunk/django django. You will see loads of output, showing all of the files that you are downloading as you install Django.

As soon as that process completes, you should run python -c "import django" to make sure everything worked properly. If the command doesn't display an ImportError, you're good. Otherwise, you need to try again.

Getting Access to Django Scripts...

Once you can successfully import django, you might want to make sure you can run the django-admin.py script that comes with Django.

sudo ln -s /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/bin/django-admin.py /usr/local/bin

sudo ln -s /usr/lib/python2.5/site-packages/django/bin/django-admin.py /usr/local/bin

mkdir ~/bin

export PATH=$HOME/bin:$PATH

source ~/.bash_rc

Install Subversion

If you haven't already installed subversion, you can download it from http://subversion.tigris.org/. You can download the svn package for a variety of platforms. If you download the source package, you should simply have to do the following as root:

• unpack the archive and enter that folder
• configure the application for your system by typing ./configure on the command line
• compile the source code by typing make
• install the package by typing make install

Note: these are the general steps for installing a package from the source; they may be slightly different with svn.

Choose A Home For The Repository

Next, choose a place for your server to keep track of all of the changes to your project. Try a place like /var/svn or /home/[your_username]/svn. I would recommend creating a folder specifically for the repository.

Create The Repository

Once you're in the directory in which you wish for your svn repository to reside, type the command svnadmin create repo or you can type the full path to be certain svnadmin create /var/svn/repo. This will create the repository.

Import Your Project

I do most of my development on my local area network, so I haven't created a repository that can be used over the Internet. I would imagine that it's pretty similar to what we do to create a repository for your LAN. Choose a project to import into your repository and navigate to the folder that the project is in. For example, if I have a project called Foo in /var/www/htdocs/foo, I would go to /var/www/htdocs. Next, use the command svn import to pull your project into the repository. For our Foo project, we would use the command svn import foo svn://localhost/var/svn/repo/foo -m "Initial Import". This will create a new folder in our repository at /var/svn/repo called foo (/var/svn/repo/foo). Our project files will put crammed into that directory for tracking.

Checkout Your Project

In order to be able to save your changes to our repository, we have to checkout the project again from the server. This is a pretty simple step, but it is critical. Even though we imported our project already, that folder remains untouched. SVN will not know how to handle the updates unless we checkout the project from the svn server. So, we proceed to checkout by removing or renaming /var/www/htdocs/foo and typing svn checkout svn://localhost/var/svn/repo/foo /var/www/htdocs/foo. This will place some hidden folders in each of the directories in your project. These hidden folders keep track of your local changes so that svn will know how to merge your changes with those of other developers.

Update The Repository

When you've made some changes that you want to save, you can send them out by typing svn commit /var/www/htdocs/foo. This command knows how to get to the server to save the changes, since the project was checked out from the repository.

Update Your Files

Sometimes you'll need to get changes that other developers have made, or revert back to a version of your project that didn't have as many problems. You can do this using the svn update command. If you're already in /var/www/htdocs/foo, you can type svn update and it will update files that have been changed in the repository since you last updated. If you're looking to get an older version of your project, you can type svn update -r PREV or a revision number in place of PREV.

Remember, these are just the basics of using SVN. You can do many amazing things with this utility. I actually did all of this as I was writing this article, so I'm sure that it works.