django/docs/faq.txt

==========
Django FAQ
==========

General questions
=================

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.

.. _Apache: http://httpd.apache.org/
.. _Python: http://www.python.org/
.. _PostgreSQL: http://www.postgresql.org/

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')."

.. _Django Reinhardt: http://en.wikipedia.org/wiki/Django_Reinhardt
.. _Wikipedia: http://en.wikipedia.org/wiki/Django_Reinhardt

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.

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`_.

.. _`cache framework`: http://www.djangoproject.com/documentation/cache/

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.

.. _`World Online`: http://code.djangoproject.com/wiki/WorldOnline
.. _`Adrian Holovaty`: http://www.holovaty.com/
.. _`chicagocrime.org`: http://www.chicagocrime.org/
.. _`Simon Willison`: http://simon.incutio.com/
.. _`simon.incutio.com`: http://simon.incutio.com/
.. _`Jacob Kaplan-Moss`: http://www.jacobian.org/
.. _`Wilson Miner`: http://www.wilsonminer.com/live/

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.

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...

Installation questions
======================

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.

.. _`Download the code`: http://www.djangoproject.com/download/
.. _`installation guide`: http://www.djangoproject.com/documentation/install/
.. _tutorial:  http://www.djangoproject.com/documentation/tutorial1/
.. _documentation: http://www.djangoproject.com/documentation/
.. _ask questions: http://www.djangoproject.com/community/

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

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

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.

.. _Python: http://www.python.org/
.. _Apache 2: http://httpd.apache.org/
.. _mod_python: http://www.modpython.org/
.. _WSGI: http://www.python.org/peps/pep-0333.html
.. _PostgreSQL: http://www.postgresql.org/
.. _MySQL: http://www.mysql.com/

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.

.. _WSGI: http://www.python.org/peps/pep-0333.html

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`_.

.. _`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
.. _`Running mod_python on Apache on Windows2000`: http://groups-beta.google.com/group/comp.lang.python/msg/139af8c83a5a9d4f
.. _`guide to getting mod_python working`: http://www.dscpl.com.au/articles/modpython-001.html

(Thanks to deelan for this info.)

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.

Using Django
============

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).

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.

The database API
================

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.

The admin site
==============

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.

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.

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.

.. _`guide to the CSS used in the admin`: http://www.djangoproject.com/documentation/admin_css/