Python script not working with django shell

i have written script to create users using csv file. i have to check the sso username is valid or not using an api request as well and its written in _validate_user function. To make the api request i'm using urllib3. Sample code provided below.

import csv
import urllib3.request
from django.contrib.auth.models import User

def _validate_user(sso_username):
    http = urllib3.PoolManager()
    fl_name = '<url>' + sso_username
    site_data = http.request('GET', fl_name)
    _data = site_data.data
    print(_data)

FILENAME = r'./csv/usernames.csv'

with atomic():
    with open(FILENAME, 'rt',  encoding='utf-8-sig') as f:
        reader = csv.DictReader(f)
        for i, row in enumerate(reader):
            user_name = row['username']
            if _validate_user(user_name):
                User.objects.get_or_create(
                    username=row['username'],
                    password='password',
                )
                print("User added")
            else:
                print("Invaid user")

when i run the code using python3 manage.py shell and input code line by line i'm not getting any error and everything is working as expected.

When i use python3 manage.py shell < utility_folder/load_users.py to run the script i'm getting NameError: name 'urllib3' is not defined at line number 6. What am i missing here. I tried with requests module also didn't do much help.

Django version is 1.11 and python 3.6

Please advice.

Use exec(open("utility_folder/load_users.py").read()) into the shell instead of python3 manage.py shell < utility_folder/load_users.py.