MySQLdb version requirement¶

Due to a bug in older versions of the MySQLdb Python module (which Django uses to connect to MySQL databases), Django’s MySQL backend now requires version 1.2.1p2 or higher of MySQLdb, and will raise exceptions if you attempt to use an older version.

If you’re currently unable to upgrade your copy of MySQLdb to meet this requirement, a separate, backwards-compatible backend, called “mysql_old”, has been added to Django. To use this backend, change the DATABASE_ENGINE setting in your Django settings file from this:

DATABASE_ENGINE = "mysql"

to this:

DATABASE_ENGINE = "mysql_old"

However, we strongly encourage MySQL users to upgrade to a more recent version of MySQLdb as soon as possible, The "mysql_old" backend is provided only to ease this transition, and is considered deprecated; aside from any necessary security fixes, it will not be actively maintained, and it will be removed in a future release of Django.

Also, note that some features, like the new DATABASE_OPTIONS setting (see the databases documentation for details), are only available on the "mysql" backend, and will not be made available for "mysql_old".

Database constraint names changed¶

The format of the constraint names Django generates for foreign key references have changed slightly. These names are generally only used when it is not possible to put the reference directly on the affected column, so they are not always visible.

The effect of this change is that running manage.py reset and similar commands against an existing database may generate SQL with the new form of constraint name, while the database itself contains constraints named in the old form; this will cause the database server to raise an error message about modifying non-existent constraints.

If you need to work around this, there are two methods available:

1. Redirect the output of manage.py to a file, and edit the generated SQL to use the correct constraint names before executing it.
2. Examine the output of manage.py sqlall to see the new-style constraint names, and use that as a guide to rename existing constraints in your database.

Name changes in manage.py¶

A few of the options to manage.py have changed with the addition of fixture support:

• There are new dumpdata and loaddata commands which, as you might expect, will dump and load data to/from the database. These commands can operate against any of Django's supported serialization formats.
• The sqlinitialdata command has been renamed to sqlcustom to emphasize that loaddata should be used for data (and sqlcustom for other custom SQL -- views, stored procedures, etc.).
• The vestigial install command has been removed. Use syncdb.

Backslash escaping changed¶

The Django database API now escapes backslashes given as query parameters. If you have any database API code that matches backslashes, and it was working before (despite the lack of escaping), you'll have to change your code to "unescape" the slashes one level.

For example, this used to work:

# Find text containing a single backslash
MyModel.objects.filter(text__contains='\\\\')

The above is now incorrect, and should be rewritten as:

# Find text containing a single backslash
MyModel.objects.filter(text__contains='\\')

Removed ENABLE_PSYCO setting¶

The ENABLE_PSYCO setting no longer exists. If your settings file includes ENABLE_PSYCO it will have no effect; to use Psyco, we recommend writing a middleware class to activate it.

New forms library¶

django.newforms is Django's new form-handling library. It's a replacement for django.forms, the old form/manipulator/validation framework. Both APIs are available in 0.96, but over the next two releases we plan to switch completely to the new forms system, and deprecate and remove the old system.

There are three elements to this transition:

• We've copied the current django.forms to django.oldforms. This allows you to upgrade your code now rather than waiting for the backwards-incompatible change and rushing to fix your code after the fact. Just change your import statements like this:

  from django import forms             # 0.95-style
  from django import oldforms as forms # 0.96-style
  

• The next official release of Django will move the current django.newforms to django.forms. This will be a backwards-incompatible change, and anyone still using the old version of django.forms at that time will need to change their import statements as described above.

• The next release after that will completely remove django.oldforms.

Although the newforms library will continue to evolve, it's ready for use for most common cases. We recommend that anyone new to form handling skip the old forms system and start with the new.

For more information about django.newforms, read the newforms documentation.

URLconf improvements¶

You can now use any callable as the callback in URLconfs (previously, only strings that referred to callables were allowed). This allows a much more natural use of URLconfs. For example, this URLconf:

from django.conf.urls.defaults import *

urlpatterns = patterns('',
    ('^myview/$', 'mysite.myapp.views.myview')
)

can now be rewritten as:

from django.conf.urls.defaults import *
from mysite.myapp.views import myview

urlpatterns = patterns('',
    ('^myview/$', myview)
)

One useful application of this can be seen when using decorators; this change allows you to apply decorators to views in your URLconf. Thus, you can make a generic view require login very easily:

from django.conf.urls.defaults import *
from django.contrib.auth.decorators import login_required
from django.views.generic.list_detail import object_list
from mysite.myapp.models import MyModel

info = {
    "queryset" : MyModel.objects.all(),
}

urlpatterns = patterns('',
    ('^myview/$', login_required(object_list), info)
)

Note that both syntaxes (strings and callables) are valid, and will continue to be valid for the foreseeable future.

The test framework¶

Django now includes a test framework so you can start transmuting fear into boredom (with apologies to Kent Beck). You can write tests based on doctest or unittest and test your views with a simple test client.

There is also new support for "fixtures" -- initial data, stored in any of the supported serialization formats, that will be loaded into your database at the start of your tests. This makes testing with real data much easier.

See the testing documentation for the full details.

Improvements to the admin interface¶

A small change, but a very nice one: dedicated views for adding and updating users have been added to the admin interface, so you no longer need to worry about working with hashed passwords in the admin.