Question

Sometimes my stupid, reckless and daredevil programming gut gets me to some dangerous places:

I’ve started a Django 1.4 application with sqlite3 and then moved to mysql, no big deal there. But then I realized that my models fit well with a NoSql model and decided to try MongoDB with django-nonrel wich is a fork of Django 1.3 with support for non-relational databases. the version 1.4 still not ready to use yet.

So, I’ve branched my repo, created my virtualenv and pipinstalled django-nonrel but when I run ./manage.py shell I got this message

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/core/management/__init__.py", line 429, in execute_from_command_line
    utility.execute()
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/core/management/__init__.py", line 252, in fetch_command
    app_name = get_commands()[subcommand]
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/core/management/__init__.py", line 101, in get_commands
    apps = settings.INSTALLED_APPS
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/utils/functional.py", line 276, in __getattr__
    self._setup()
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/conf/__init__.py", line 42, in _setup
    self._wrapped = Settings(settings_module)
  File "/Users/marcoslhc/Documents/Proyectos/fontcase/mongoBE/lib/python2.7/site-packages/django/conf/__init__.py", line 139, in __init__
    logging_config_func(self.LOGGING)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/logging/config.py", line 776, in dictConfig
    dictConfigClass(config).configure()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/logging/config.py", line 562, in configure
    'filter %r: %s' % (name, e))
ValueError: Unable to configure filter 'require_debug_false': Cannot resolve 'django.utils.log.RequireDebugFalse': No module named RequireDebugFalse

RequireDebugFalse is new in Django 1.4 (see here and here) and I guess some other underlying magic new in 1.4 would not work either in this new installation. I was wondering if I can migrate back my application to Django 1.3 without doing django-admin.py startproject or django-admin.py startapp.

Answer 1

You can do that, although you probably want to leave the door open to going forward again.

The way I’ve handled this in the past is, if at all possible, to not go making massive changes to your code. Instead, do what you’ve already done — run the code and wait for it to blow up. Identify what the source of the problem is and then do one of the following:

• Create a stub that supplies the needed functionality (or at least quietly does nothing),
• Back-port the functionality onto your own personal copy of 1.3, or
• Monkey-patch the functionality onto an unmodified 1.3. (My recommendation)

Unless you have totally glommed onto some unique new feature in 1.4, you’d be surprised how quickly you can come up with a useable environment. I had one project where the monkey-patch file was only about 100 lines long to retrofit about a dozen features onto an older version.