What is different about "./manage.py shell" vs. normal Python shell that makes this list comprehension not work anymore?

[cseb...@gmail.com]

I noticed a list comprehension bombs in the "./manage.py shell" shell that I think would

be ok in normal Python shell.  What is different about "./manage.py shell"

that makes it not like certain list comprehensions?

Here is the code erase that I run this way..."./manage.py shell < erase"

import bighelp.models

ACCT  = bighelp.models.Account

ASERV = bighelp.models.AccountService

APPT  = bighelp.models.Appointment

for e in ACCT.objects.all()[:1]:

        appts       = APPT.objects.filter(account = e)[:3]

        aservs      = ASERV.objects.filter(account = e)

        allowed     = [e.service.name for e in aservs]

        print(f"allowed is a list of strings => {allowed}\n\n")

        print(f"appts is a collection of Django objects => {appts}\n\n")

        print("This way of defining servs works...\n\n")

        servs       = []

        for a in appts:

                if a.service in allowed:

                        servs.append(a.service)

        print(f"servs   = {servs}\n\n")

        print("This way gives a mysterious error...\n\n")

        servs = [a.service for a in appts if (a.service in allowed)]

***THE OUTPUT****

../manage.py shell < ./erase

allowed is a list of strings => ['pet', 'cleaning']

appts is a collection of Django objects => <QuerySet [<Appointment: Appointment object (998)>, <Appointment: Appointment object (1463561)>, <Appointment: Appointment object (863)>]>

This way of defining servs works...

servs   = ['cleaning', 'pet', 'cleaning']

This way gives a mysterious error...

Traceback (most recent call last):

  File "../manage.py", line 8, in <module>

    django.core.management.execute_from_command_line(sys.argv)

  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 381, in execute_from_command_line

    utility.execute()

  File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 375, in execute

    self.fetch_command(subcommand).run_from_argv(self.argv)

  File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 323, in run_from_argv

    self.execute(*args, **cmd_options)

  File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 364, in execute

    output = self.handle(*args, **options)

  File "/usr/lib/python3/dist-packages/django/core/management/commands/shell.py", line 92, in handle

    exec(sys.stdin.read())

  File "<string>", line 26, in <module>

  File "<string>", line 26, in <listcomp>

NameError: name 'allowed' is not defined

[Josué Alvarez]

Try with:

 

global allowed

allowed     = [e.service.name for e in aservs]

...

servs = [a.service for a in appts if (a.service in allowed)]

[Christian Seberino]

Josue

Thanks so much!  That makes so much sense.  

I really appreciate it.

Sincerely,

Chris

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