python-learning-journey

Learning Python from the ground up

🐍 Python Learning Journey

Welcome to my structured path for learning Python — from the basics to web development with CGI and Flask.
This repository is both a learning journal and a reference library, showing my progression step by step.

A structured learning project covering Python basics through databases and web integration.
Sensitive credentials are never committed — they are managed securely using .env files and excluded from Git with .gitignore.

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📂 Project Structure

python-learning-journey/
├── 01_basics/
│   ├── hello_world.py
│   ├── variables.py
│   ├── input_output.py
│   └── math_operations.py
├── 02_control_flow/
│   ├── if_else.py
│   ├── loops.py
│   └── break_continue.py
├── 03_functions/
│   ├── functions_intro.py
│   ├── lambda_functions.py
│   ├── scope.py
│   ├── docstrings.py
│   ├── args_kwargs.py
│   └── recursion_examples.py
├── 04_oop/
│   ├── classes_objects.py
│   ├── inheritance.py
│   ├── polymorphism.py
│   ├── encapsulation.py
│   └── class_methods_static.py
├── 05_web_basics/
│   ├── cgi_hello.py
│   ├── cgi_form.py
│   ├── cgi_env.py
│   └── cgi_error.py
├── 06_flask_intro/
│   ├── app.py
│   ├── form_demo.py
│   └── templates/
│       ├── home.html
│       ├── about.html
│       └── contact.html
├── 07_databases/
│   ├── mysql_demo.py
│   └── templates/
│       └── users.html
└── README.md

01_basics

• hello_world.py → Prints "Hello World" to demonstrate Python’s simplest output.
• variables_demo.py → Shows variable assignment and basic data types.
• loops_demo.py → Demonstrates for and while loops with simple examples.

02_data_structures

• list_examples.py → Basic list operations: append, slice, iterate.
• dict_examples.py → Key/value storage and retrieval with dictionaries.
• set_examples.py → Demonstrates uniqueness and set operations.

03_functions_and_modules

• functions_demo.py → Defines and calls functions with parameters and return values.
• modules_demo.py → Imports built‑in modules and shows modular code structure.

04_oop

• class_demo.py → Defines a simple class with attributes and methods.
• inheritance_demo.py → Demonstrates subclassing and method overriding.
• polymorphism_demo.py → Shows how different classes can share behavior.

05_web_basics

• cgi_hello.py → A simple “Hello World” CGI script that outputs static HTML.
• cgi_form.py → Handles user input from an HTML form and dynamically responds.
• cgi_env.py → Displays CGI environment variables passed by Apache.
• cgi_error.py → Demonstrates error handling in CGI scripts.

06_flask_intro

• app.py → Flask app with multiple routes (/, /about, /contact) demonstrating navigation and template rendering.
• templates/home.html → Home page template with links to About and Contact.
• templates/about.html → About page template describing the app.
• templates/contact.html → Contact form template that accepts name, email, and message, and displays a confirmation.
• form_demo.py → Standalone script demonstrating GET/POST form handling directly with render_template_string.

07_databases

This section introduces database integration with Flask using MySQL.

Files

• mysql_demo.py → Flask app that connects to MySQL using mysqlclient (MySQLdb) and environment variables for credentials.
• templates/users.html → Template that lists users retrieved from the database.

Setup

1. Create the database and table in MySQL:

   CREATE DATABASE python_learning;
   USE python_learning;
   
   CREATE TABLE users (
       id INT AUTO_INCREMENT PRIMARY KEY,
       name VARCHAR(80)
   );
   
   INSERT INTO users (name) VALUES ('Alice'), ('Bob'), ('Charlie');
   
   ## Database Configuration & Security
   

This project uses a config.py file to manage database connection settings.
Sensitive information such as usernames and passwords are never committed to Git. Instead, they are stored in a local .env file and loaded at runtime using python-dotenv.

How it works

• .env contains environment variables (e.g., MYSQL_USER, MYSQL_PASSWORD).
• config.py loads these variables securely with dotenv.
• .gitignore excludes both config.py and .env to prevent accidental commits.

Example .env

MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=your_secure_password
MYSQL_DATABASE=python_learning

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## ✅ Why This Helps
- Shows recruiters I understand **security and reproducibility**.
- Makes it clear collaborators should set up their own `.env` file.
- Reinforces that your repo is clean — no secrets in history.

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Perfect — here’s a concise **Setup Instructions** section I can drop into your README so collaborators (or recruiters) know exactly how to run your database demo securely:

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## ⚙️ Setup Instructions

To run the database examples in `07_databases`, follow these steps:

1. **Install dependencies**
   ```bash
   pip install python-dotenv mysql-connector-python

2. Create a .env file at the project root (same level as README.md):

   MYSQL_HOST=localhost
   MYSQL_USER=root
   MYSQL_PASSWORD=your_secure_password
   MYSQL_DATABASE=python_learning

3. Verify .gitignore excludes sensitive files:

   07_databases/config.py
   .env
   

4. Run the demo

   python 07_databases/mysql_demo.py

5. Confirm environment variables are loaded

   python -c "import config; print(config.MYSQL)"

   → should print your connection dictionary with values from .env.

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✅ Why This Helps

• Keeps credentials out of GitHub history.
• Makes setup reproducible for anyone cloning your repo.
• Shows recruiters I understand secure, professional workflows.

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🔄 Workflow Diagram +------------------+ | .env | | (stores secrets) | +------------------+ | v +------------------+ | config.py | | loads with | | python-dotenv | +------------------+ | v +------------------+ | mysql_demo.py | | uses MYSQL dict | | for connection | +------------------+