Fixed #29301 -- Added custom help formatter to BaseCommand class

This partially reverts c3055242.
Thanks Adam Johnson and Carlton Gibson for the reviews.

django/core/management/base.py

@@ -4,7 +4,7 @@ be executed through ``django-admin`` or ``manage.py``).
 """
 import os
 import sys
-from argparse import ArgumentParser
+from argparse import ArgumentParser, HelpFormatter
 from io import TextIOBase
 
 import django
@@ -88,6 +88,29 @@ def no_translations(handle_func):
     return wrapped
 
 
+class DjangoHelpFormatter(HelpFormatter):
+    """
+    Customized formatter so that command-specific arguments appear in the
+    --help output before arguments common to all commands.
+    """
+    show_last = {
+        '--version', '--verbosity', '--traceback', '--settings', '--pythonpath',
+        '--no-color',
+    }
+
+    def _reordered_actions(self, actions):
+        return sorted(
+            actions,
+            key=lambda a: set(a.option_strings) & self.show_last != set()
+        )
+
+    def add_usage(self, usage, actions, *args, **kwargs):
+        super().add_usage(usage, self._reordered_actions(actions), *args, **kwargs)
+
+    def add_arguments(self, actions):
+        super().add_arguments(self._reordered_actions(actions))
+
+
 class OutputWrapper(TextIOBase):
     """
     Wrapper around stdout/stderr
@@ -229,12 +252,10 @@ class BaseCommand:
         parser = CommandParser(
             prog='%s %s' % (os.path.basename(prog_name), subcommand),
             description=self.help or None,
+            formatter_class=DjangoHelpFormatter,
             missing_args_message=getattr(self, 'missing_args_message', None),
             called_from_command_line=getattr(self, '_called_from_command_line', None),
         )
-        # Add command-specific arguments first so that they appear in the
-        # --help output before arguments common to all commands.
-        self.add_arguments(parser)
         parser.add_argument('--version', action='version', version=self.get_version())
         parser.add_argument(
             '-v', '--verbosity', action='store', dest='verbosity', default=1,
@@ -258,6 +279,7 @@ class BaseCommand:
             '--no-color', action='store_true', dest='no_color',
             help="Don't colorize the command output.",
         )
+        self.add_arguments(parser)
         return parser
 
     def add_arguments(self, parser):

docs/releases/2.1.txt

@@ -145,6 +145,11 @@ Management Commands
 * The new :option:`inspectdb --include-views` option allows creating models
   for database views.
 
+* The :class:`~django.core.management.BaseCommand` class now uses a custom help
+  formatter so that the standard options like ``--verbosity`` or ``--settings``
+  appear last in the help output, giving a more prominent position to subclassed
+  command's options.
+
 Migrations
 ~~~~~~~~~~
 

tests/user_commands/management/commands/common_args.py

+from argparse import ArgumentError
+
+from django.core.management.base import BaseCommand, CommandError
+
+
+class Command(BaseCommand):
+    def add_arguments(self, parser):
+        try:
+            parser.add_argument('--version', action='version', version='A.B.C')
+        except ArgumentError:
+            pass
+        else:
+            raise CommandError('--version argument does no yet exist')
+
+    def handle(self, *args, **options):
+        return 'Detected that --version already exists'

tests/user_commands/tests.py

@@ -205,6 +205,11 @@ class CommandTests(SimpleTestCase):
         self.assertIn('need_me', out.getvalue())
         self.assertIn('needme2', out.getvalue())
 
+    def test_command_add_arguments_after_common_arguments(self):
+        out = StringIO()
+        management.call_command('common_args', stdout=out)
+        self.assertIn('Detected that --version already exists', out.getvalue())
+
     def test_subparser(self):
         out = StringIO()
         management.call_command('subparser', 'foo', 12, stdout=out)