Convert core commands to use self.std(out|err) instead of sys.std(out|err)/print

[mmcnickle]

Some core management commands are using raw "print" statements and calls to sys.stdout/sys.stderr instead of self.stdout/self.stderr. This causes an inconsistency between commands when people specify their own buffers when using django.core.management.call_command:

out = StringIO()
err = StringIO()
call_command('command', stdout=out, stderr=err)
...

[Russell Keith-Magee]

For background -- the transition to self.stdout/stderr was done to ensure easy testing, and as a side effect, to allow Django commands to be used as a service. We've converted those commands that needed to be converted for the purpose of Django's own testing; the remainder is left as a work in progress.

[Adam Vandenberg]

Use self.stderr|out instead of print or sys.

[Jannis Leidel]

I would rather like to see the logging module be used here, if possible as we've seen a tremendous slowdown when we've ported the staticfiles app to django and removed the logging from commands.

[Adam Vandenberg]

@jezdez If you point me to an example where logging is used "the right way", I'll try to work up a patch.

[Jannis Leidel]

In django-staticfiles we had an own management command specific logger mixin, ​https://github.com/jezdez/django-staticfiles/blob/0.3.4/staticfiles/management/base.py but I admit that's a bit cumbersome given our new logging API in 1.3. I'd like to propose to add an additional logger (next to the 'django', 'django.request' and 'django.db.backends' loggers (​http://docs.djangoproject.com/en/dev/topics/logging/#id1), e.g. 'django.managment.commands' or 'django.commands'.

[Jacob]

Milestone 1.3 deleted

[Claude Paroz]

Commands output through logging

[Claude Paroz]

I worked on a refactor of commands output using logging infrastructure, adding new BaseCommand.info() and BaseCommand.error() proxy methods, and deprecating self.stderr and self.stdout. Hopefully this is in the right direction, as of jezdez comment:5.

[Claude Paroz]

Just a note to any potential reviewer: as this patch is quite extensive, I will keep a local branch updated with current trunk. However, I will not spam this ticket each time I rebase my branch. So just ping me if/when you are interested to review it (hopefully during the 1.5 timeframe!)

[Claude Paroz]

Updated to current trunk

[Mike <leachim@…>]

@claudep
If BaseCommand has .info() and .error(), it might be nice to be complete and include .debug(), .warning() and .critical(), that also get output to the stdout/stderr passed to the command.

Then the verbosity argument could potentially be updated to also take strings, so you could for example do -v W to only have output at warning level or higher.

[Claude Paroz]

Thanks Mike, that's an interesting comment. I'd like to push patch for #18325 first, then rewrite this one with your idea in mind.

[Claude Paroz]

Let's close this one in favour of #21429