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Build a personal URL shortener in Python

Written by

Bernardo Palos

in

Building a personal URL shortener in Python is a great project to practice web development, databases, and routing. Below is a minimal, functional version using Flask and SQLite. This basic version allows you to shorten URLs, store them in a database, and redirect to the original URL when the short URL is accessed.

Step-by-step: Personal URL Shortener using Flask and SQLite

✅ Requirements:

Install Flask and SQLite (SQLite comes preinstalled with Python):

bash
pip install flask

🔧 Project Structure:

pgsql
url_shortener/
│
├── app.py
└── templates/
    ├── index.html
    └── result.html

📄 app.py

python
import string
import random
import sqlite3
from flask import Flask, request, redirect, render_template, url_for

app = Flask(__name__)
DATABASE = 'urls.db'

def get_db():
    conn = sqlite3.connect(DATABASE)
    conn.execute('CREATE TABLE IF NOT EXISTS urls (id INTEGER PRIMARY KEY, original TEXT, short TEXT)')
    return conn

def generate_short_id(num_chars=6):
    return ''.join(random.choices(string.ascii_letters + string.digits, k=num_chars))

@app.route('/', methods=['GET', 'POST'])
def index():
    if request.method == 'POST':
        original_url = request.form['original_url']
        conn = get_db()
        cursor = conn.cursor()

        # Check if URL already exists
        cursor.execute("SELECT short FROM urls WHERE original = ?", (original_url,))
        row = cursor.fetchone()
        if row:
            short_id = row[0]
        else:
            short_id = generate_short_id()
            cursor.execute("INSERT INTO urls (original, short) VALUES (?, ?)", (original_url, short_id))
            conn.commit()

        conn.close()
        return render_template('result.html', short_url=request.host_url + short_id)
    return render_template('index.html')

@app.route('/<short_id>')
def redirect_short_url(short_id):
    conn = get_db()
    cursor = conn.cursor()
    cursor.execute("SELECT original FROM urls WHERE short = ?", (short_id,))
    row = cursor.fetchone()
    conn.close()

    if row:
        return redirect(row[0])
    return f'Invalid URL: {short_id}', 404

if __name__ == '__main__':
    app.run(debug=True)

🧾 templates/index.html

html
<!DOCTYPE html>
<html>
<head>
    <title>URL Shortener</title>
</head>
<body>
    <h2>Shorten your URL</h2>
    <form method="post">
        <input type="url" name="original_url" placeholder="Enter URL" required>
        <input type="submit" value="Shorten">
    </form>
</body>
</html>

🧾 templates/result.html

html
<!DOCTYPE html>
<html>
<head>
    <title>Short URL</title>
</head>
<body>
    <h2>Your short URL is:</h2>
    <a href="{{ short_url }}">{{ short_url }}</a>
</body>
</html>

▶️ How to Run:

In your terminal:

bash
cd url_shortener
python app.py

Visit http://127.0.0.1:5000 in your browser.

🛡️ Enhancements (Optional):

  • Add custom short URLs.

  • Use a better random string generator with collision checking.

  • Add analytics (click count, IP logging).

  • Use a production-grade database like PostgreSQL.

  • Deploy with Gunicorn + Nginx on a VPS or Heroku.

Would you like deployment instructions or enhancements like custom aliases or analytics tracking?

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