Django and Python keep releasing new versions, so I wanted to take some notes as I start a new project in October of 2023.

Tools I’ll be using:

asdf – I use this to manage python versions (an easy way to have multiple version of python installed and be able to have different directories/projects use different versions)

pipenv – is “a Python virtualenv management tool that supports a multitude of systems and nicely bridges the gaps between pip, python (using system python, pyenv or asdf) and virtualenv”

python – your favorite program language

django – your favorite high level python web framework.

Let’s get started – python first

python --version
Python 3.9.14

While that’s a huge step ahead of Python2, for this new project I want the latest and most stable.

asdf latest python
3.12.0

I have no reason to have on the .0 version, but let’s see what asdf has for version 3.11

asdf latest python 3.11
3.11.6

OK – that sounds good. Let’s use that.

asdf update
asdf install python 3.11.6
asdf reshim python 3.11.6
asdf local python 3.11.6   # This 

Now that we have 3.11.6, let’s create the directory that we want to use for the project.

python --version  # let's see what the "global version is"
Python 3.9.14     # still set to the older version

mkdir my-new-project
cd my-new-project
asdf local python 3.11.6

python --version  # what about now?
Python 3.11.6     # OK, that's good enough for me

Time to get pipenv going

So, I had a bit of a hard time getting pipenv to work with the newest asdf version of python. Here’s what helped:

# make sure you are in the correct project directory
# and that the directory is empty

python -m pip install --upgrade pip
pip install pipenv

pipenv --python 3.11

Here's a screenshot for what happened.

I want to show you what happens if you have an existing Pipfile in the directory, and if that Pipfile contains a python [requires] section that looks like this:

...
[requires]
python_version = "3.9"
...

Now for some django

pipenv install "django>=4"

Once django is installed, you will need to fire it up:

pipenv shell

django-admin startproject config .

Note in the above I used the word “config” — I intentionally choose to do that so that all of my config files end up in that config directory. And actually I’ll do a little bit more than that by converting the settings.py file into a settings/ folder with:

mkdir config/settings
cp config/init.py config/settings
mv config/settings.py config/settings/base.py

# Create a new config file by running this cat command
# cut and paste from first "cut" to final "EOF" in a shell

cat <<EOF > config/settings/local.py
# Django settings
#

# These are the settings for a local environment
from .base import *
EOF

What about the database?

In my live environments I always use PostreSQL, so I mimic that behavior on my local machines by running on PostgreSQL locally on my Ubuntu server (via WSL2)

Don’t forget to add in the psycopg2 pip library

pipenv install psycopg2

After that, you’ll need to login as the postgres user on your machine, and create the database and assign a password.

sudo su - postgres

# do this inside of the postgres account

postgres_db_and_user=tvcodes
createuser $postgres_db_and_user
createdb -O $postgres_db_and_user  $postgres_db_and_user

psql
## these next commands are INSIDE the postgresql shell

alter user xxxxDBUSERNAMExxxx with encrypted password 'whatever_password_should_be';

(hint: https://bitwarden.com/password-generator/)

what does that look like?

psql
psql (14.9 (Ubuntu 14.9-0ubuntu0.22.04.1))
Type "help" for help.

postgres=# alter user my_awesome_project with encrypted password 'whatever_password_should_be';
ALTER ROLE
postgres=# quit
postgres@localhost:~$ 
logout

And what do the variables look like?

DATABASE_URL=postgres://my_awesome_project:whatever_password_should_be@localhost:5432/my_awesome_project

Let’s use local environment variables

We want to NOT put important variables directly in the code, so the modern day solution is to use environment variables. I’m influenced by: https://pypi.org/project/environs/

pipenv install environs[django]

Now create a .env file at the same level as your manage.py file that looks like this:

cat <<EOF > .env
#
DJANGO_SETTINGS_MODULE=config.settings.local
#
DEBUG=True
SECRET_KEY="not so secret on local"

DATABASE_URL=postgres://my_awesome_project:whatever_password_should_be@127.0.0.1:5432/flytest
EOF

Let’s login locally

Let’s create a user we can login with:

python manage.py migrate
python manage.py createsuperuser
python manage.py runserver 0.0.0.0:8000

NOTE: This might fail if you don’t have environment variables configured yet. If using VSCode,

I recently upgraded from python 3.9.12 to 3.9.14 using asdf, and it was pretty simple:

sudo apt-get install liblzma-dev
asdf install python 3.9.14
asdf global python 3.9.14

But when I tried to run my pipenv, it didn’t work as planned

pipenv shell
No preset version installed for command pipenv
Please install a version by running one of the following:

asdf install python 3.9.14

or add one of the following versions in your config file at /home/mark/.tool-versions
python 3.9.12

After a lot of failed attemps to use asdf reshim and asdf update, I finally remembered the magic steps to use:

python -m pip install --upgrade pip
pip install pipenv

asdf update
asdf reshim python 3.9.14   # or whatever newest version is

pipenv install
pipenv shell
pipenv update   # To actually install what was in Pipfile

The last trick that I needed to do was make sure that my .env gets read so that any Python environment variables I set are correctly read in.

vi ~/.local/share/virtualenvs/hostname-RANDOM/bin/activate

And add these 2 lines starting at line 4 of the activate script:

# Use this sequence to load up the environnment variables from your .env file in a Bash console:
#
set -a; source /home/mark/home/aei/aeicloud.22/.env; set +a

I’ll be using asdf to help control what version of Python I’m running.

I like pipenv to help manage my Python virtual environments.

I like to use PostgreSQL with Django, so lets’ first make sure that it’s installed:

sudo apt install postgresql 
sudo apt install libpq-dev

# make sure it's running
# You should see it listening to lots of ports
ss -nlt

asdf

git clone https://github.com/asdf-vm/asdf.git ~/.asdf --branch v0.10.0

# modify .bashrc files, exit terminal and restart terminal

sudo apt-get update
sudo apt-get upgrade

# install packages necessary to build stuff
sudo apt install wget build-essential libreadline-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev libffi-dev zlib1g-dev liblzma-dev

asdf plugin-add python

asdf install python 3.9.12
asdf global python 3.9.12

If the correct version of Python isn’t detected, you might need to reshim.

python -m pip install --upgrade pip
pip install pipenv

asdf update
asdf reshim python 3.9.12

pipenv install

[pipenv.exceptions.ResolutionFailure]: Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies.
You can use $ pipenv install –skip-lock to bypass this mechanism, then run $ pipenv graph to inspect the situation.
Hint: try $ pipenv lock –pre if it is a pre-release dependency.
ERROR: metadata generation failed

Turned out the above error, was because I didn’t have postgres installed on the new box (and my django uses postgres)

 Error: pg_config executable not found.

I got much futher along

# how to know things are almost all the way there
./manage.py shell

python manage.py dbshell

# If you didn't setup your postgres, you'll get an error like:
# python manage.py dbshell
# psql: error: connection to server at "127.0.0.1", port 5432 failed: Connection refused
#         Is the server running on that host and accepting TCP/IP connections?

You’ll need to start the server:

sudo service postgresql start

Then try

python manage.py dbshell
psql: error: connection to server at "127.0.0.1", port 5432 failed: FATAL:  password authentication failed for user "abcuser"
connection to server at "127.0.0.1", port 5432 failed: FATAL:  password authentication failed for user "abcuser"

The user and database don’t appear to exist — so let’s create them:

sudo su - postgres
# skipping the lines as you login as user postgres


psql
# now you are in the postgres shell

CREATE DATABASE abcdb;
CREATE USER abcuser WITH PASSWORD 'abc123';

\q     # that exists the postgres shell

exit   # that logs out the postgres user

You should now be able to init the DB

python manage.py migrate
python manage.py createsuperuser

# then run any bootstrapping that you need to
# python manage.py loaddata  xyz.json

# needed for pango and weasyprint (creating PDFs)
sudo apt-get install libpangocairo-1.0-0

Now, to get django working in VSCode

1. install the Python extension for Visual Studio Code
2. Press F1, then choose Python: Select Interpreter and make sure you are pointing to your correct venv
3. Press the Run and Debug Icon