Ошибка из моего ведома при выполнении скрипта python

Question

Я написал скрипт python, чтобы заполнить мою базу данных поддельными данными, используя библиотеку Faker для случайного проекта, пока я изучаю Django. Мой проект называется «ProTwo», и внутри этого проекта есть приложение под названием «apptwo». Это сценарий python, который я написал: (populate_users.py)

 import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", 'ProTwo.settings')

import django
django.setup()

from apptwo.models import User
from faker import Faker


fakegen = Faker()

def populate(N=5):

        for entry in range(N):
            fake_name = fakegen.name().split()
            fake_first_name = fake_name[0]
            fake_last_name = fake_name[1]
            fake_email = fakegen.email()

            user = User.objects.get_or_create(first_name = fake_first_name, last_name = fake_last_name, email = fake_email)[0]
            user.save()


if __name__ == '__main__':
    print('POPULATING DATABASES!')
    populate(20)
    print('POPULATION DONE!')

models.py:

 from django.db import models


class User(models.Model):
    first_name = models.CharField(max_length = 264,null = True)
    last_name = models.CharField(max_length = 264, null = True)
    email = models.EmailField(max_length=254, unique = True)

(views.py):

from django.shortcuts import render
from django.http import HttpResponse
from apptwo.models import User



def index(request):
    return render(request,'app_two/index.html')

def users(request):
    user_list = User.objects.order_by('first_name')
    user_dict = {'users': user_list}
    return render(request,'app_two/users.html', context = user_dict)

(urls.py):

from django.contrib import admin
from django.conf.urls import url, include
from apptwo import views

urlpatterns = [
    url(r'^$',views.index, name = 'index'),
    url('admin/', admin.site.urls),
    url(r'^users/', include('apptwo.urls')),
]

, и это ошибка при выполнении команды 'python populate_users.py', и я выполнил все необходимые миграции:

    Traceback (most recent call last):
  File "populate_users.py", line 27, in <module>
    populate(20)
  File "populate_users.py", line 21, in populate
    user = User.objects.get_or_create(first_name = fake_first_name, last_name = fake_last_name, email = fake_email)[0]
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\query.py", line 562, in get_or_create
    return self._create_object_from_params(kwargs, params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\query.py", line 604, in _create_object_from_params
    raise e
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\query.py", line 596, in _create_object_from_params
    obj = self.create(**params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\query.py", line 433, in create
    obj.save(force_insert=True, using=self.db)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\base.py", line 745, in save
    self.save_base(using=using, force_insert=force_insert,
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\base.py", line 782, in save_base
    updated = self._save_table(
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\base.py", line 887, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\base.py", line 924, in _do_insert
    return manager._insert(
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\query.py", line 1204, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\models\sql\compiler.py", line 1384, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\utils.py", line 100, in execute
    return super().execute(sql, params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\harsh\anaconda3\envs\newEnv\lib\site-packages\django\db\backends\sqlite3\base.py", line 396, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: apptwo_user.First_name