Django Unlocked: Beginners' Spawn Point

Introduction

Django is a powerful web framework that allows you to build robust, scalable web applications quickly and efficiently. It’s written in Python and follows the "batteries-included" philosophy, meaning it comes with a lot of built-in features that make development faster and easier, thus making it suitable for prototyping. Whether you're creating a small personal project or a large enterprise application, Django has the tools you need.

In this guide, I’ll walk you through Django’s MVT design pattern (Models, Views, and Templates), providing a solid foundation for building your own web applications. By the end, you'll have a clear understanding of how Django works and how to use its components effectively.

Setting Up a Django Project with a Virtual Environment

Refer to the official documentation of Django: Django Documentation

Before diving into the core components, let’s set up a virtual environment to manage your project’s dependencies. This helps keep your project isolated and prevents conflicts with other Python projects.

Note: I highly encourage using Linux. If you are using Windows, install WSL to access the Linux environment.

1. Install venv module:

sudo apt install python3-venv

2. Create a Virtual Environment:

python -m venv .venv

3. Activate the Virtual Environment:

source .venv/bin/activate

4. Install Django:

With the virtual environment activated, install Django:

python -m pip install django

5. Create a Django Project:

django-admin startproject myproj

Replace myproj with your desired project name.

6. Create an App:

Inside your project directory, create an app.

python manage.py startapp myapp

7. Add your newly created app to the settings.py located in:

your-project-name/your-project-name/settings.py

INSTALLED_APPS = [
    'myapp',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

Your project is now set up with a basic structure, including a manage.py file, project settings, and your first app

Models

Models define the structure of your database tables and the relationships between them using Python classes. Each model class maps to a single database table, and each attribute of the model corresponds to a database field. Django simplifies this process by allowing you to define your database schema using classes that inherit from django.db.models.Model.

ORM stands for Object-Relational Mapping. In Django, the ORM is a powerful feature that allows developers to interact with the database using Python code instead of writing SQL queries. This abstraction layer maps Python classes (models) to database tables and instances of those classes to rows in the table.

Introducing SQLite

Django uses SQLite as its default database because it's super easy to set up. SQLite is a lightweight database that keeps all your data in one simple file, so you don’t have to install anything extra to start saving and managing your website’s data. This makes it a great choice for development and testing, as it allows you to focus on building your application without worrying about complex database setups.

Example: In Django, a table named Airport with attributes like 'code' and 'city' is represented as a Python class, where each attribute is defined as a class variable.

class Airport(models.Model):
    code = models.CharField(max_length=3)
    city = models.CharField(max_length=64)

1. Defining Models:

In models.py of your app, define your models using Django’s ORM.

from django.db import models

class Flight(models.Model):
    # Diri, kada flight naa tay origin kung asa gikan, destination, ug duration
    # Nakabutang sa parameters ilang properties, such as length of the characters

    origin = models.ForeignKey(Airport, on_delete=models.CASCADE, related_name='departures')
    destination = models.ForeignKey(Airport, on_delete=models.CASCADE, related_name='arrivals')
    duration = models.IntegerField()

    def __str__(self):
        return f'{self.id}: {self.origin} to {self.destination} | {self.duration} minutes.'

2. Migrations:

After defining your models, create and apply migrations to update your database schema.

In simple terms:

• makemigrations is like planning the changes you want to make to your databse.
• migrate is actually carrying out those changes on the database. So, after planning with makemigrations, migrate is when you execute and apply the changes.

python manage.py makemigrations
python manage.py migrate

3. Interacting with Models:

Use Django's shell to interact with your models: python manage.py shell

Example:

>> from flights.models import Flight

>> flight1 = Flight(origin="Davao", destination="Manila", duration=569)
>> fligh1.save()

I created an instance of the Flights model. This instance flight1 represents a single row in the Flight table of my database. The Flight model has fields origin, destination, and duration defined in it.
When you create the instance. you are setting these fields to specific values:

• origin : "Davao"
• destination : "Manila"
• duration : 569 (representing the flight duration in minutes)

Views

Views are a crucial part of the framework that handles the logic behind what a user sees and interacts with in a web application. Views are responsible for processing user requests, retrieving necessary data from the database, and returning the appropriate response (typically an HTML page, JSON data, or a redirect).

In simple terms, Views in Django act as the middleman between the web pages and the data. They take requests from users, process any necessary data, and then send back the appropriate response, like a webpage or a file. Essentially, views decide what content should be shown to the user and how it should be presented.

In this read, we will only be using Function-Based Views

1. Function-Based Views:

These are Python functions that take a web request and return a web response. The most basic view in Django is a function that receives a request object and returns a response object.

from django.http import HttpResponse

def index(request):
    return HttpResponse("Hello, World!")

2. Class-Based Views:

These are Python classes that provide more structure and allow for more complex functionality compared to Function-Based Views.

from django.views import View
from django.http import HttpResponse

class MyView(View):
    def get(self, request):
        return HttpResponse("Hello, World!")

Templates

Templates are used to render HTML and display data to users. They allow you to separate your HTML from Python code. Django templates are a powerful tool for generating dynamic HTML content in your web application. By separating the presentation (HTML) from the backend logic (Python code), templates help keep your code clean, maintainable, and reusable.

In simple terms, Templates in Django are like blueprints that define how data should be displayed on a webpage. They allow you to combine static content (like HTML) with dynamic content (like data from a database) to create a fully rendered page. Instead of hardcoding every detail, you use templates to keep the design and data separate, making it easier to update and manage your website.

1. Creating a Template

Start with creating a directory for your templates inside your app and name the directory as templates. Create another directory inside the templates named myapp.

django-proj/myapp/templates/myapp

Now, you can finally place all your templates inside the inner directory you created:

django-proj/myapp/templates/myapp/base.html

Creating the base.html allows you to define a base template or layout with common structure (headers, navbar, and footer) that other templates can inherit. This feature is useful for maintaining consistency across different pages.

Example:

<!DOCTYPE html>
<html>
<head>
    <title> {% block title %} myApp {% endblock %} </title>
</head>
<body>
    <header>
        <h1>My Site</h1>
    </header>
    <div class="content">
        {% block content %}{% endblock %}
    </div>
    <footer>
        <p>Footer content here</p>
    </footer>
</body>
</html>

Let's create another template called index.html and place it in the same directory of base.html.

Example of extending template index.html:

{% extends "myapp/base.html" %}
{% block content %}
    <h1>Flights</h1>
    <ul>
        {% for flight in flights %}
            <li>Flight: {{ flight.id }} {{ flight.origin }} to {{ flight.destination }}</li>
        {% endfor %}
    </ul>
{% endblock %}

The {% extends "myapp/base.html" %} tells Django to use the base.html as the base layout template. The {% block content %} defines a block of content that will be filled with content from index.html. The content block in base.html will be replaced with the content provided in index.html.

2. Rendering Templates

In a Django view, you typically render a template using the render() function, which combines the template with the context data to produce the final HTML output.

from django.shortcuts import render

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

When Django renders index.html, it will include the structure from base.html, replacing the content block with the content specified in index.html. This allows for consistent design across pages and makes it easy to update the overall layout without changing every individual template.

URLs and Routing

Django uses URL patterns to map URLs to views. These patterns are defined in a file called urls.py within each Django app.

URL patterns are defined with the path() function, mapping specific URL paths to view functions or classes. Dynamic URL segments, such as <int:post_id>, allow for capturing variables from the URL to be used in views. The include() function enables modular URL management by including patterns from other apps.

In simple terms, URLs are like street addresses for different pages on your website. Routing is the system that makes sure when someone types in a specific address (URL), they get directed to the right page. You set up these "addresses" in a special file so Django knows where to send people when they visit your site.

1. Configuring URLs:
Define URL patterns in urls.py of your app:

from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
]

Include your app's URLs in the project's urls.py:

from django.contrib import admin
from django.urls import include, path

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('myapp.urls'))
]

Wrapping up

Congratulations! You've taken the first steps in learning Django. I’ve covered the basics of Models, Views, Templates, and URL routing. With these fundamentals, you’re on your way to building your own Django applications. Keep experimenting, keep coding, and don't hesitate to dive deeper into the Django documentation and community resources.

I hope this guide has made these concepts clearer and that you’ve learned something valuable along the way.

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