Complete Guide to Flask Web Development

Why Choose Flask?

Flask is a micro web framework for Python that's perfect for both beginners and experienced developers. It's lightweight, flexible, and easy to learn.

Setting Up Your Flask Project

Installation

pip install flask
pip install python-dotenv  # For environment variables

Basic Application Structure

from flask import Flask, render_template

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

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

Routing and URL Building

Flask makes routing simple and intuitive:

@app.route('/user/')
def profile(username):
    return f'Profile page for {username}'

@app.route('/post/')
def show_post(post_id):
    return f'Post {post_id}'

Templates with Jinja2

Flask uses Jinja2 templating engine:

{% verbatim %}



    


    {% block content %}{% endblock %}

{% endverbatim %}

Forms and User Input

Handle forms securely with Flask-WTF:

from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired

class ContactForm(FlaskForm):
    name = StringField('Name', validators=[DataRequired()])
    submit = SubmitField('Submit')

Database Integration

Use Flask-SQLAlchemy for database operations:

from flask_sqlalchemy import SQLAlchemy

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)

RESTful APIs with Flask

Build APIs easily:

from flask import jsonify

@app.route('/api/users')
def get_users():
    users = User.query.all()
    return jsonify([u.to_dict() for u in users])

Deployment Best Practices

• Use environment variables for sensitive data
• Set debug=False in production
• Use a production WSGI server like Gunicorn
• Implement proper error handling
• Add logging for monitoring

Conclusion

Flask is an excellent choice for web development in Python. Its simplicity and flexibility make it perfect for projects of any size. Start building today!