Creating a Django Application

What is a Django Application?

A Django application is a web application that performs a specific task (e.g., creating, reading, updating, and deleting an object). To perform these tasks, your application needs to have a model, view, template, forms, and URLs.

Remember that you need to create a project before making an application, and your project will most likely include many applications. I usually create an application for each real-life entity. For example, a patient can have multiple addresses. For this instance, you may want to create apps named patients and addresses.

How to Create a Django Application?

1. Activate your virtual environment

Before creating an application, you have to activate your virtual environment.

2. Navigate to the Django project directory

Let us use the Gen EMR project (an electronic medical record) as an example. Open up your terminal and navigate to the directory below:

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| - gen_emr/
    | - gen_emr_src/
        | - gen_emr/  --> Open up this directory.
            | - gen_emr/
                | - __init__.py
                | - asgi.py
                | - settings.py
                | - urls.py
                | - wsgi.py
            | - manage.py
    | - gen_emr_venv/

The official Django documentation mentioned that a project is a collection of configurations and apps for a particular website. With this, the default project layout wants us to put all the applications inside a project directory. Let us go with that for now.

3. Create a new Django application

We want to create a Django application called users. Run the following command to create a new application:

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python manage.py startapp users

This creates a directory named users with the following structure:

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| - gen_emr/
    | - gen_emr_src/
        | - gen_emr/
            | - gen_emr/
                | - __init__.py
                | - asgi.py
                | - settings.py
                | - urls.py
                | - wsgi.py
            | - users/  --> New
                | - migrations/  --> New
                    | - __init__.py  --> New
                | - __init__.py  --> New
                | - admin.py  --> New
                | - apps.py  --> New
                | - models.py  --> New
                | - tests.py  --> New
                | - views.py  --> New
            | - db.sqlite3  --> New
            | - manage.py
    | - gen_emr_venv/

• migrations/: A directory that contains the database migrations of the application.

• __init__.py: An empty file that tells Python that this directory is a Python package.

• admin.py: A file to include your models in the Django admin interface.

• apps.py: The main configuration of the application.

• models.py: Define the data structure (database models) for your app.

• tests.py: Write tests for your app.

• views.py: Define the logic for handling requests and returning responses.

Why did Django Generate the db.sqlite3?

SQLite is a lightweight, serverless database engine that stores all data in a single file. db.sqlite3 is the default SQLite database file used by Django when setting up a new project.

At this point, we have not changed anything in settings.py.

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DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.sqlite3",
        "NAME": BASE_DIR / "db.sqlite3",
    }
}

The creation of db.sqlite3 is not directly caused by the startapp command itself.

When you run the command python manage.py startapp users, Django initializes various components specified in your settings.py, including the DATABASES configuration. This process creates the db.sqlite3.