::-- limodou [2005-07-20 02:02:01]

Contents

Django FAQ

1. Django FAQ

1.1. General questions

1.1.1. Why does this project exist?

Django grew from a very practical need: in our fast-paced newsroom, we often have only a matter of hours to take a complicated Web application from concept to public launch. Django was designed to not only allow us to build Web applications quickly, but to allow us to build them right.

Django would not be possible without a whole host of open-source projects -- Apache, Python, and PostgreSQL to name a few -- and we're thrilled to be able to give something back to the open-source community.

1.1.2. What does "Django" mean, and how do you pronounce it?

Django is named after Django Reinhardt, a gypsy jazz guitarist from the 1930s to early 1950s. To this day, he's considered one of the best guitarists of all time.

Listen to his music. You'll like it.

According to Wikipedia, "Django is pronounced zhane-go (with a long 'a')."

1.1.3. Is Django stable?

We've been using Django for almost two years. Sites built on Django have weathered traffic spikes of over one million hits an hour, and at least one Slashdotting. Yes, it's quite stable.

1.1.4. Does Django scale?

Yes. Compared to development time, hardware is cheap, and so Django is designed to take advantage of as much hardware as you can throw at it. Django ships with clean separation of the database layer from the application layer and a simple-yet-powerful cache framework.

1.1.5. Who's behind this?

Django was developed at World Online, the Web department of a newspaper in Lawrence, Kansas, USA.

Adrian Holovaty
Adrian is a gypsy-jazz virtuoso, an amateur Beatles historian and a proud Chicagoan. He's also a pretty decent programmer, with a knack for whipping data into shape and putting it to work for the good of his fellow man. Adrian is the lead developer at World Online and the man behind the code at chicagocrime.org. He lives in Chicago.
Simon Willison Simon is a well-respected Web developer from England. He had a one-year internship at World Online, during which time he and Adrian developed Django from scratch. He's enthusiastic, he's passionate about best practices in Web development, and he really likes squirrels. Probably to a fault. He went back to university to finish his degree and is poised to continue doing big, exciting things on the Web. He lives in England.
Jacob Kaplan-Moss Jacob is a whipper-snapper from California who spends equal time coding and cooking. He does Web development for World Online and actively hacks on various cool side projects. He's contributed to the Python-ObjC bindings and was the first guy to figure out how to write Tivo apps in Python. Lately he's been messing with Python on the PSP. He lives in Lawrence, Kansas.
Wilson Miner Wilson's design-fu makes us all look like rock stars. When not sneaking into apartment complex swimming pools he is the Commercial Development Director for World Online, which means he makes the money that pays all our paychecks. He lives in Lawrence, Kansas.

1.1.6. Django appears to be a MVC framework, but you call the Controller the "view", and the View the "template". How come you don't use the standard names?

That's because Django isn't strictly a MVC framework. We don't really believe in any capital-M Methodologies; we do what "feels" right. If you squint the right way, you can call Django's ORM the "Model", the view functions the "View", and the dynamically-generated API the "Controller" -- but not really.

So, although we've been strongly influenced by MVC -- especially in the separation-of-data-from-logic department -- we've also strayed from the path where it makes sense.

1.1.7. Do you have any of those nifty "screencast" things?

They're in the works. It's amazing how much time those things take! Stay tuned...

1.2. Installation questions

1.2.1. How do I get started?

Download the code.
Install Django (read the installation guide).
Walk through the tutorial.
Check out the rest of the documentation, and ask questions if you run into trouble.

1.2.2. How do I fix the "install a later version of setuptools" error?

Just run the ex_setup.py script in the Django distribution.

1.2.3. What are Django's prerequisites?

Django requires Python 2.3 or later.

For a development environment -- if you just want to experiment with Django -- you don't need to have a separate Web server installed; Django comes with its own lightweight development server. For a production environment, we recommend Apache 2 and mod_python, although Django follows the WSGI spec, which means it can run on a variety of server platforms.

You'll also need a database engine. PostgreSQL is recommended, and MySQL is supported.

1.2.4. Do I have to use mod_python?

Not if you just want to play around and develop things on your local computer. Django comes with its own Web server, and things should Just Work.

For production use, though, we recommend mod_python. The Django developers have been running it on mod_python for about two years, and it's quite stable.

However, if you don't want to use mod_python, you can use a different server, as long as that server has WSGI hooks. More information on alternate server arrangements is forthcoming.

1.2.5. How do I install mod_python on Windows?

For Python 2.4, check out this guide to mod_python & Python 2.3.
For Python 2.3, grab mod_python from http://www.mod_python.org/ and read Running mod_python on Apache on Windows2000.
Also, try this (not Windows-specific) guide to getting mod_python working.

(Thanks to deelan for this info.)

1.2.6. Will Django run under shared hosting (like TextDrive or Dreamhost)?

Right now, no, unless you can get your host to install mod_python. However, as the community starts to use Django's WSGI bindings with other Web servers, this will probably be possible sooner rather than later.

1.3. Using Django

1.3.1. Why do I get an error about importing DJANGO_SETTINGS_MODULE?

Make sure that:

- The environment variable DJANGO_SETTINGS_MODULE is set to a fully-qualified Python module (i.e. "mysite.settings.main").
- Said module is on sys.path (import mysite.settings.main should work).
- The module doesn't contain syntax errors (of course).
- If you're using mod_python but not using Django's request handler, you'll need to work around a mod_python bug related to the use of SetEnv; before you import anything from Django you'll need to do the following:
```
os.environ.update(req.subprocess_env)
```
  (where req is the mod_python request object).

1.3.2. I can't stand your template language. Do I have to use it?

We happen to think our template engine is the best thing since chunky bacon, but we recognize that choosing a template language runs close to religion. There's nothing about Django that requires using the template language, so if you're attached to ZPT, Cheetah, or whatever, feel free to use those.

1.4. The database API

1.4.1. How can I see the raw SQL queries Django is running?

Make sure your Django DEBUG setting is set to True. Then, just do this:

>>> from django.core.db import db
>>> db.queries
[{'sql': 'SELECT polls_polls.id,polls_polls.question,polls_polls.pub_date FROM polls_polls',
'time': '0.002'}]

db.queries is only available if DEBUG is True. It's a list of dictionaries in order of query execution. Each dictionary has the following:

``sql`` -- The raw SQL statement
``time`` -- How long the statement took to execute, in seconds.

1.5. The admin site

1.5.1. I can't log in. When I enter a valid username and password, it just brings up the login page again, with no error messages.

The login cookie isn't being set correctly, because the domain of the cookie sent out by Django doesn't match the domain in your browser. Try these two things:

Set the REGISTRATION_COOKIE_DOMAIN setting to match your domain. For example, if you're going to "http://www.mysite.com/admin/" in your browser, set REGISTRATION_COOKIE_DOMAIN = 'www.mysite.com'.
Some browsers (Firefox?) don't like to accept cookies from domains that don't have dots in them. If you're running the admin site on "localhost" or another domain that doesn't have a dot in it, try going to "localhost.localdomain" or "127.0.0.1". And set REGISTRATION_COOKIE_DOMAIN accordingly.

1.5.2. I can't log in. When I enter a valid username and password, it brings up the login page again, with a "Please enter a correct username and password" error.

If you're sure your username and password are correct, make sure your user account has is_active and is_staff set to True. The admin site only allows access to users with those two fields both set to True.

1.5.3. The dynamically-generated admin site is ugly! How can I change it?

We think it's very purty, but if you don't agree, you can modify the admin site's presentation by editing the CSS stylesheet and/or associated image files. The site is built using semantic HTML, so any changes you'd like to make should be possible by editing the CSS stylesheet. We've got a guide to the CSS used in the admin to get you started.