Can Django manage.py custom commands return a value? How, or why not?

Question

Following the documentation: https://docs.djangoproject.com/en/dev/howto/custom-management-commands/

I created my own custom command (called something else but example shown below):

from django.core.management.base import BaseCommand, CommandError from polls.models import Poll  class Command(BaseCommand):     args = '<poll_id poll_id ...>'     help = 'Closes the specified poll for voting'      def handle(self, *args, **options):         for poll_id in args:             try:                 poll = Poll.objects.get(pk=int(poll_id))             except Poll.DoesNotExist:                 raise CommandError('Poll "%s" does not exist' % poll_id)              poll.opened = False             poll.save()              self.stdout.write('Successfully closed poll "%s"' % poll_id)          return "Yay" 

The question is how come returning a string like "Yay" does not work? Am I doing it wrong or is it not possible?

When I call the custom command from my view, I do something like:

     value = call_command('call_custom_command', parameter)      print value 

but the value is shown to be None.

Answer 1

If you want to get the output of call_command(), you need to capture stdout. Here's how you can do it:

out = StringIO() call_command('call_custom_command', stdout=out)  value = out.getvalue() print value 

This technique is actually used in django tests for testing management commands.

Demo:

>>> from django.core.management import call_command >>> from StringIO import StringIO >>> out = StringIO() >>> call_command('validate', stdout=out) >>> out.getvalue() '0 errors found\n' 

Hope that helps.