python manage.py makemigrations giving error on upgrading django

Question

My project was working fine with django 1.11

This is my manage.py file

#!/usr/bin/env python
import os
import sys

if __name__ == "__main__":
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myfoodsite.settings")
    try:
        from django.core.management import execute_from_command_line
    except ImportError:
        # The above import may fail for some other reason. Ensure that the
        # issue is really that Django is missing to avoid masking other
        # exceptions on Python 2.
        try:
            import django
        except ImportError:
            raise ImportError(
                "Couldn't import Django. Are you sure it's installed and "
                "available on your PYTHONPATH environment variable? Did you "
                "forget to activate a virtual environment?"
            )
        raise
    execute_from_command_line(sys.argv)

until I upgraded my django to django 2.0.0

By using pip install python=2.0.0 , The output was as follows

(myvenv) shubhendu@shubhendu-HP-Pavilion-g6-Notebook-PC:/home/foodballbear$ python manage.py makemigrations
Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/home/foodballbear/myvenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/home/foodballbear/myvenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 347, in execute
    django.setup()
  File "/home/foodballbear/myvenv/lib/python3.5/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/foodballbear/myvenv/lib/python3.5/site-packages/django/apps/registry.py", line 112, in populate
    app_config.import_models()
  File "/home/foodballbear/myvenv/lib/python3.5/site-packages/django/apps/config.py", line 198, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/home/foodballbear/block/models.py", line 41, in <module>
    class Post(models.Model):
  File "/home/foodballbear/block/models.py", line 42, in Post
    author = models.ForeignKey('auth.User')
TypeError: __init__() missing 1 required positional argument: 'on_delete'

I am now developing it well on Django 1.11 but how can I make it run on Django 2.0?

Answer 1

As documentation for ForeignKey in Django 1.1 states on_delete is becoming required in Django 2.0

ForeignKey

A many-to-one relationship. Requires two positional arguments: the class to which the model is related and the on_delete option. (on_delete isn't actually required, but not providing it gives a deprecation warning. It will be required in Django 2.0.)

Also your error points to the same

author = models.ForeignKey('auth.User')
TypeError: __init__() missing 1 required positional argument: 'on_delete'

You should set on_delete attribute on each foreign key for it to be Django 2.0 compatible