mfonism/dropping_python_2_support_in_django-user-accounts.md

## dropping_python_2_support_in_django-user-accounts.md

      
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    Dropping Python 2 Support in Django User Accounts

This gist documents the steps that were taken to drop Python 2 support in
Django User Accounts,
an app in the Pinax project.
It is for most of the part similar to
this other gist, which documents the steps that were taken to drop support in Pinax Ratings,
another app in the Pinax project.


Remove Python 2 from test matrix


Remove redundant future statements/features
print_functon and unicode_literals in this case, as they are enabled in Python 3 by default.


Drop compatibility handling in account.compat


The django.core.urlresolvers module was moved to
django.urls in version 1.10, and deprecated in version 2.0
The lowest version of Django in this app is 1.11, so
we can safely use functions from the latter module.


Also, as of Django 1.10, user.is_authenticated is a property, and not a method.
We can therefore safely drop that part of the compatibility handling, too.


Drop account.compat

account.compat.NoReverseMatch ==> django.urls.NoReverseMatch
account.compat.resolve ==> django.urls.resolve
account.compat.reverse ==> django.urls.reverse
account.compat.is_authenticated(user) ==> user.is_authenticated


Drop unicode compatibility handlers


Drop django.utils.six

django.utils.six.moves.reduce ==> functools.reduce
django.utils.six.StringIO ==> io.StringIO
django.utils.six.moves.urllib.parse.urlparse ==> urllib.parse.urlparse


Drop compatibility handlers for stdlib modules

collections.OrderedDict exists across all supported versions of Python
urlparse.urlparse ==> urllib.parse.urlparse
urlparse.urlunparse ==> urllib.parse.urlunparse


Prefer settings.MIDDLEWARE to settings.MIDDLEWARE_CLASSES

The MIDDLEWARE_CLASSES setting was deprecated in Django 1.10 and
the MIDDLEWARE setting took precedence.
Support for the old-style MIDDLEWARE_CLASSES setting was
dropped in Django 2.0


Update setup and docs


Fix issues identified by deepsource


PERFORMAMCE issue in account/models.py
1 occurence of inheriting from object


ANTI-PATTERN in account/templatetags/account_tags.py
1 occurrence of using len without comparison to determine if a sequence is empty
if len(bits):
    ...
Was changed to:
if len(bits) > 0:
    ...


BUG RISK in account/auth_backends.py
Match parameters in overriding methods with those in the respective overriden methods
def authenticate(self, *args, **credentials):
    ...
Was changed to
def authenticate(self, request, username=None, password=None, **kwargs):
    ...
Also, the body of the function was updated accordingly.


ANTI-PATTERN in account/models.py
Drop occurrences of re-defining variables from outer scope.
def now(self):
    now = datetime.datetime.utcnow().replace(tzinfo=pytz.timezone("UTC"))
    timezone = settings.TIME_ZONE if not self.timezone else self.timezone
    return now.astimezone(pytz.timezone(timezone))
Was updated to
def now(self):
    now = datetime.datetime.utcnow().replace(tzinfo=pytz.timezone("UTC"))
    tz = settings.TIME_ZONE if not self.timezone else self.timezone
    return now.astimezone(pytz.timezone(tz))
In order to avoid shadowing the Python timezone library which was imported at the top-level


ALERT!: Deepsource also identified four style issues which I couldn't wrap my head around 😓.