Django Examples

A starter project for Clark's Databases course (CSCI 220). This project includes a web server and database.

Follow these steps to get started:

Step 0: Clone This Repository

Unless otherwise specified, all commands mentioned below should be run within the root directory of this repository.

Step 1: Install Docker

This project includes several components:

• uWSGI, which will run your Django application code
• NGINX, a web server which will allow browsers to communicate with uWSGI
• PostgresSQL, a database which will store your application's persistent data

It could be time-consuming to install and configure all of these on your computer, but thankfully there is a better way: Docker! Install Docker, and it will be easy to run all of these components.

Step 2: Secure Configuration

It is a terrible idea to run software with default passwords. To configure the password for the database and other settings, you will need to write them in a .env file. Follow these steps:

1. Copy dot_env_example to .env
2. Run chmod 600 .env to prevent other users from reading your .env file
3. Edit .env, changing:

• The text RANDOM_PASSWORD to a password which is actually random
• The text SOMETHING_LONG_AND_RANDOM to random text, ideally generated using the Python one-liner below:

python3 -c "import string,random; uni=string.ascii_letters+string.digits; print(''.join([random.SystemRandom().choice(uni) for i in range(random.randint(45,50))]))"

Step 3: Start the Docker Services

Run:

docker compose up

The first time you run it, this command will take a few minutes to complete. This is because Docker needs to download the code for PostgresSQL, etc.

When you are done running the application, you can stop it by typing Control-C.

Step 4: Run Migrations

Follow the instructions below to run the database migrations. This will ensure the database has the schema for the applications.

Step 5: Load the Applications

Load http://localhost:8080 and you should be redirected to the "Django administration" login interface.

Load http://localhost:8080/minifacebook to view the latest statuses of users of the minifacebook application. See instructions below for using the Django admin interface, which you can use to create users and status updates.

Hints

Creating Admin Accounts

To create a superuser, which can access the Django admin interface:

docker compose exec django python manage.py createsuperuser

To create a regular user, load /admin/auth/user/add/ in your browser.

You can then log into the Django admin interface using this superuser account.

Database Operations

Manual Commands

To interactively run SQL commands, run:

> docker compose exec postgres bash
# psql --username="$POSTGRES_USER" --dbname="$POSTGRES_DB"

Migrations

When you edit Django models, the changes don't take effect until you update the database. This is done in two steps.

First, you create a migration file, which describes the changes to be made:

docker compose exec django python manage.py makemigrations

Then, you apply those changes by running the migration file:

docker compose exec django python manage.py migrate

You can read more about Django migrations here.

Dump

To dump the SQL commands needed to recreate a database to file, run:

> docker compose exec postgres bash
# pg_dump --username="$POSTGRES_USER" --dbname="$POSTGRES_DB" --file=/postgres_files/db_dump.DATE.sql

Load

To execute SQL commands from a file, run:

> docker compose exec postgres bash
# psql --username="$POSTGRES_USER" --dbname="$POSTGRES_DB" --set ON_ERROR_STOP=on --file /postgres_files/db_dump.DATE.sql