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280 lines
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280 lines
12 KiB
Plaintext
==========
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Django FAQ
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==========
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General questions
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=================
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Why does this project exist?
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----------------------------
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Django grew from a very practical need: in our fast-paced newsroom, we often
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have only a matter of hours to take a complicated Web application from
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concept to public launch. Django was designed to not only allow us to
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build Web applications quickly, but to allow us to build them right.
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Django would not be possible without a whole host of open-source projects --
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`Apache`_, `Python`_, and `PostgreSQL`_ to name a few -- and we're thrilled to be
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able to give something back to the open-source community.
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.. _Apache: http://httpd.apache.org/
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.. _Python: http://www.python.org/
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.. _PostgreSQL: http://www.postgresql.org/
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What does "Django" mean, and how do you pronounce it?
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-----------------------------------------------------
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Django is named after `Django Reinhardt`_, a gypsy jazz guitarist from the 1930s
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to early 1950s. To this day, he's considered one of the best guitarists of all time.
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Listen to his music. You'll like it.
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According to Wikipedia_, "Django is pronounced **zhane**-go (with a long 'a')."
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.. _Django Reinhardt: http://en.wikipedia.org/wiki/Django_Reinhardt
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.. _Wikipedia: http://en.wikipedia.org/wiki/Django_Reinhardt
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Is Django stable?
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-----------------
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We've been using Django for almost two years. Sites built on Django have
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weathered traffic spikes of over one million hits an hour, and at least
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one Slashdotting. Yes, it's quite stable.
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Does Django scale?
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------------------
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Yes. Compared to development time, hardware is cheap, and so Django is
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designed to take advantage of as much hardware as you can throw at it.
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Django ships with clean separation of the database layer from the
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application layer and a simple-yet-powerful `cache framework`_.
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.. _`cache framework`: http://www.djangoproject.com/documentation/cache/
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Who's behind this?
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------------------
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Django was developed at `World Online`_, the Web department of a newspaper in
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Lawrence, Kansas, USA.
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`Adrian Holovaty`_
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Adrian is a gypsy-jazz virtuoso, an amateur Beatles historian and a proud
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Chicagoan. He's also a pretty decent programmer, with a knack for whipping
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data into shape and putting it to work for the good of his fellow man.
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Adrian is the lead developer at World Online and the man behind the code at
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`chicagocrime.org`_. He lives in Chicago.
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`Simon Willison`_
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Simon is a well-respected Web developer from England. He had a one-year
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internship at World Online, during which time he and Adrian developed
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Django from scratch. He's enthusiastic, he's passionate about best
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practices in Web development, and he really likes squirrels. Probably to a
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fault. He went back to university to finish his degree and is poised to
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continue doing big, exciting things on the Web. He lives in England.
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`Jacob Kaplan-Moss`_
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Jacob is a whipper-snapper from California who spends equal time coding and
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cooking. He does Web development for World Online and actively hacks on
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various cool side projects. He's contributed to the Python-ObjC bindings and
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was the first guy to figure out how to write Tivo apps in Python. Lately
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he's been messing with Python on the PSP. He lives in Lawrence, Kansas.
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`Wilson Miner`_
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Wilson's design-fu makes us all look like rock stars. When not sneaking
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into apartment complex swimming pools he is the Commercial Development
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Director for World Online, which means he makes the money that pays all our
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paychecks. He lives in Lawrence, Kansas.
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.. _`World Online`: http://code.djangoproject.com/wiki/WorldOnline
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.. _`Adrian Holovaty`: http://www.holovaty.com/
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.. _`chicagocrime.org`: http://www.chicagocrime.org/
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.. _`Simon Willison`: http://simon.incutio.com/
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.. _`simon.incutio.com`: http://simon.incutio.com/
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.. _`Jacob Kaplan-Moss`: http://www.jacobian.org/
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.. _`Wilson Miner`: http://www.wilsonminer.com/live/
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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?
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-----------------------------------------------------------------------------------------------------------------------------------------------------
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That's because Django isn't strictly a MVC framework. We don't really believe in
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any capital-M Methodologies; we do what "feels" right. If you squint the right
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way, you can call Django's ORM the "Model", the view functions the "View", and
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the dynamically-generated API the "Controller" -- but not really.
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So, although we've been strongly influenced by MVC -- especially in the
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separation-of-data-from-logic department -- we've also strayed from the path
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where it makes sense.
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Do you have any of those nifty "screencast" things?
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---------------------------------------------------
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They're in the works. It's amazing how much time those things take! Stay tuned...
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Installation questions
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======================
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How do I get started?
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---------------------
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#. `Download the code`_.
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#. Install Django (read the `installation guide`_).
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#. Walk through the tutorial_.
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#. Check out the rest of the documentation_, and `ask questions`_ if you
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run into trouble.
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.. _`Download the code`: http://www.djangoproject.com/download/
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.. _`installation guide`: http://www.djangoproject.com/documentation/install/
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.. _tutorial: http://www.djangoproject.com/documentation/tutorial1/
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.. _documentation: http://www.djangoproject.com/documentation/
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.. _ask questions: http://www.djangoproject.com/community/
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How do I fix the "install a later version of setuptools" error?
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---------------------------------------------------------------
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Just run the ``ex_setup.py`` script in the Django distribution.
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What are Django's prerequisites?
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--------------------------------
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Django requires Python_ 2.3 or later.
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For a development environment -- if you just want to experiment with Django --
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you don't need to have a separate Web server installed; Django comes with its
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own lightweight development server. For a production environment, we recommend
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`Apache 2`_ and mod_python_, although Django follows the WSGI_ spec, which
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means it can run on a variety of server platforms.
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You'll also need a database engine. PostgreSQL_ is recommended, and MySQL_ is
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supported.
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.. _Python: http://www.python.org/
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.. _Apache 2: http://httpd.apache.org/
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.. _mod_python: http://www.modpython.org/
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.. _WSGI: http://www.python.org/peps/pep-0333.html
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.. _PostgreSQL: http://www.postgresql.org/
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.. _MySQL: http://www.mysql.com/
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Do I have to use mod_python?
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----------------------------
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Not if you just want to play around and develop things on your local computer.
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Django comes with its own Web server, and things should Just Work.
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For production use, though, we recommend mod_python. The Django developers have
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been running it on mod_python for about two years, and it's quite stable.
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However, if you don't want to use mod_python, you can use a different server,
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as long as that server has WSGI_ hooks. More information on alternate server
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arrangements is forthcoming.
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.. _WSGI: http://www.python.org/peps/pep-0333.html
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How do I install mod_python on Windows?
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---------------------------------------
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* For Python 2.4, check out this `guide to mod_python & Python 2.3`_.
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* For Python 2.3, grab mod_python from http://www.mod_python.org/ and read
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`Running mod_python on Apache on Windows2000`_.
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* Also, try this (not Windows-specific) `guide to getting mod_python working`_.
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.. _`guide to mod_python & Python 2.3`: http://www.lehuen.com/nicolas/index.php/2005/02/21/39-win32-build-of-mod_python-314-for-python-24
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.. _`Running mod_python on Apache on Windows2000`: http://groups-beta.google.com/group/comp.lang.python/msg/139af8c83a5a9d4f
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.. _`guide to getting mod_python working`: http://www.dscpl.com.au/articles/modpython-001.html
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(Thanks to deelan for this info.)
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Will Django run under shared hosting (like TextDrive or Dreamhost)?
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-------------------------------------------------------------------
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Right now, no, unless you can get your host to install mod_python. However, as
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the community starts to use Django's WSGI bindings with other Web servers, this
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will probably be possible sooner rather than later.
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Using Django
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============
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Why do I get an error about importing DJANGO_SETTINGS_MODULE?
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-------------------------------------------------------------
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Make sure that:
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* The environment variable DJANGO_SETTINGS_MODULE is set to a fully-qualified
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Python module (i.e. "mysite.settings.main").
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* Said module is on ``sys.path`` (``import mysite.settings.main`` should work).
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* The module doesn't contain syntax errors (of course).
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* If you're using mod_python but *not* using Django's request handler,
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you'll need to work around a mod_python bug related to the use of
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``SetEnv``; before you import anything from Django you'll need to do
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the following::
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os.environ.update(req.subprocess_env)
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(where ``req`` is the mod_python request object).
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I can't stand your template language. Do I have to use it?
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----------------------------------------------------------
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We happen to think our template engine is the best thing since chunky bacon,
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but we recognize that choosing a template language runs close to religion.
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There's nothing about Django that requires using the template language, so
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if you're attached to ZPT, Cheetah, or whatever, feel free to use those.
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The database API
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================
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How can I see the raw SQL queries Django is running?
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----------------------------------------------------
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Make sure your Django ``DEBUG`` setting is set to ``True``. Then, just do
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this::
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>>> from django.core.db import db
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>>> db.queries
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[{'sql': 'SELECT polls_polls.id,polls_polls.question,polls_polls.pub_date FROM polls_polls',
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'time': '0.002'}]
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``db.queries`` is only available if ``DEBUG`` is ``True``. It's a list of
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dictionaries in order of query execution. Each dictionary has the following::
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``sql`` -- The raw SQL statement
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``time`` -- How long the statement took to execute, in seconds.
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The admin site
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==============
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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.
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---------------------------------------------------------------------------------------------------------------------------
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The login cookie isn't being set correctly, because the domain of the cookie
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sent out by Django doesn't match the domain in your browser. Try these two
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things:
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* Set the ``REGISTRATION_COOKIE_DOMAIN`` setting to match your domain. For
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example, if you're going to "http://www.mysite.com/admin/" in your browser,
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set ``REGISTRATION_COOKIE_DOMAIN = 'www.mysite.com'``.
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* Some browsers (Firefox?) don't like to accept cookies from domains that don't
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have dots in them. If you're running the admin site on "localhost" or another
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domain that doesn't have a dot in it, try going to "localhost.localdomain" or
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"127.0.0.1". And set ``REGISTRATION_COOKIE_DOMAIN`` accordingly.
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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.
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-----------------------------------------------------------------------------------------------------------------------------------------------------------
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If you're sure your username and password are correct, make sure your user
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account has ``is_active`` and ``is_staff`` set to True. The admin site only
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allows access to users with those two fields both set to True.
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The dynamically-generated admin site is ugly! How can I change it?
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------------------------------------------------------------------
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We think it's very purty, but if you don't agree, you can modify the admin
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site's presentation by editing the CSS stylesheet and/or associated image files.
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The site is built using semantic HTML, so any changes you'd like to make should
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be possible by editing the CSS stylesheet. We've got a `guide to the CSS used in
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the admin`_ to get you started.
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.. _`guide to the CSS used in the admin`: http://www.djangoproject.com/documentation/admin_css/
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