TypeError: not all arguments converted during string formatting in django

Question

I'm having a bit of trouble using str.format(*args, **kwargs):

import datetime
from django.conf import settings
from django.core.management.base import BaseCommand
from django.core.mail import send_mass_mail
from django.contrib.auth.models import User
from django.db.models import Count


class Command(BaseCommand):

    def add_arguments(self, parser):
        parser.add_argument('--days', dest='days', type=int)

    def handle(self, *args, **options):
        emails = []
        subject = 'Enroll in a course'
        date_joined = datetime.date.today() - datetime.timedelta(days=options['days'])
        users = User.objects.annotate(course_count=Count('courses_joined'))
                    .filter(course_count=0, date_joined__lte=date_joined)
        for user in users:
            message = 'Dear {},\n\n What are you waiting for?'.format(user.first_name)
            emails.append((subject, message, settings.DEFAULT_FROM_EMAIL, [user.email]))
        send_mass_mail(emails)
        countEmails = len(emails)
        if countEmails:
            # self.stdout.write(countEmails)
            messageConsole = 'Sent {} reminders.' % format(int(countEmails))
            self.stdout.write(messageConsole)

Run command "python manage.py enroll_reminder --days=1", then the errro comes:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/__init__.py", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/base.py", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/base.py", line 445, in execute
    output = self.handle(*args, **options)
  File "/home/polar/PythonLab/DjangoByExample/educa/students/management/commands/enroll_reminder.py", line 30, in handle
    messageConsole = 'Sent {} reminders.\n' % format(int(countEmails))
TypeError: not all arguments converted during string formatting

when I uncomment "self.stdout.write(countEmails)", there comes another problem:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/__init__.py", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/base.py", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/base.py", line 445, in execute
    output = self.handle(*args, **options)
  File "/home/polar/PythonLab/DjangoByExample/educa/students/management/commands/enroll_reminder.py", line 29, in handle
    self.stdout.write(countEmails)
  File "/home/polar/.pyenv/versions/my_env/lib/python3.5/site-packages/django/core/management/base.py", line 111, in write
    if ending and not msg.endswith(ending):
AttributeError: 'int' object has no attribute 'endswith'

Can anyone help show me what I am doing wrong?

Thank you!

How silly I am for this stupid question......shame on me.

polar9527
– polar9527

2016-07-08 13:10:50 +00:00
Commented Jul 8, 2016 at 13:10 — polar9527
– polar9527, Commented Jul 8, 2016 at 13:10

Daniel Roseman · Accepted Answer · 2016-07-08 12:32:50Z

3

You're confused between the old C-style string substitution and the new format method. Either do:

'Sent {} reminders.'.format(int(countEmails))

or

'Sent %s reminders.' % (int(countEmails),)

answered Jul 8, 2016 at 12:32

Daniel Roseman

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1 Comment

polar9527 Over a year ago

This is the second time that you helped me, thank you!

Alasdair · Accepted Answer · 2016-07-08 12:32:24Z

3

You are confusing % and .format() formatting

You could do either:

'Sent {} reminders'.format(countEmails)

or

'Sent %d reminders.' % countEmails

Note that countEmails is already an integer, there is no need to call int(countEmails).

answered Jul 8, 2016 at 12:32

Alasdair

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