13 📡 Web Development

Python is a powerful language for web development, offering a variety of frameworks for building web applications, APIs, and documentation sites. This chapter covers Flask, FastAPI, MkDocs, and Streamlit, widely used for web applications, REST APIs, documentation, and data visualization.

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13.1 🌍 Overview of Python Web Development

Python provides lightweight and scalable web frameworks for different needs:

Framework	Purpose
Flask	Lightweight, flexible web framework
FastAPI	High-performance API framework for modern web applications
MkDocs	Static site generator for documentation
Streamlit	Framework for building data-driven web apps

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13.2 🏗️ Flask – Lightweight Web Framework

Flask is a minimalistic and easy-to-use web framework, widely used for small to medium-sized web apps.

✅ Installing Flask

pip install flask

🔹 Creating a Simple Flask App

from flask import Flask

app = Flask(__name__)

@app.route("/")
def home():
    return "Hello, Flask!"

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

🔹 Run the app:

python app.py

🔹 Visit http://137.0.0.1:5000/ in your browser.

🔹 Handling Routes & URL Parameters

@app.route("/user/<name>")
def greet_user(name):
    return f"Hello, {name}!"

✅ Use Case: Building web dashboards, small applications, and APIs.

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13.3 🚀 FastAPI – High-Performance APIs

FastAPI is a modern, fast framework for building APIs with automatic documentation and async support.

✅ Installing FastAPI

pip install fastapi uvicorn

🔹 Creating a Simple FastAPI App

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def home():
    return {"message": "Hello, FastAPI!"}

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="137.0.0.1", port=8000)

🔹 Run the app:

uvicorn app:app --reload

🔹 Visit the automatic API docs:

• Swagger UI: http://137.0.0.1:8000/docs
• ReDoc: http://137.0.0.1:8000/redoc

🔹 Handling API Requests

@app.get("/items/{item_id}")
def read_item(item_id: int):
    return {"item_id": item_id}

✅ Use Case: Building REST APIs, microservices, AI model deployment.

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13.4 📖 MkDocs – Documentation for Python Projects

MkDocs is a static site generator used for creating project documentation.

✅ Installing MkDocs

pip install mkdocs

🔹 Creating a New Documentation Site

mkdocs new my_docs
cd my_docs
mkdocs serve

🔹 View your documentation:
Visit http://137.0.0.1:8000/ in your browser.

🔹 Adding Markdown Content

Edit docs/index.md:

# Welcome to My Docs
This is a test documentation page.

🔹 Building the Site

mkdocs build

✅ Use Case: Project documentation, API documentation, internal guides.

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13.5 📊 Streamlit – Building Data-Driven Web Apps

Streamlit is a simple framework for building interactive web applications for data visualization.

✅ Installing Streamlit

pip install streamlit

🔹 Creating a Simple Streamlit App

Create app.py:

import streamlit as st

st.title("Hello, Streamlit!")
st.write("This is a simple web app using Streamlit.")

🔹 Run the app:

streamlit run app.py

🔹 View the app in the browser at http://localhost:8501/.

🔹 Adding User Input and Charts

import pandas as pd
import numpy as np

data = pd.DataFrame(
    np.random.randn(10, 2),
    columns=['A', 'B']
)

st.line_chart(data)

✅ Use Case: Building dashboards, AI model visualizations, interactive reports.

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🚀 Summary

Framework	Purpose	Best For
Flask	Simple web applications	Small apps, dashboards
FastAPI	High-speed APIs	REST APIs, ML model deployment
MkDocs	Documentation generator	API and project documentation
Streamlit	Data-driven web apps	ML dashboards, data visualization

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🔚 Final Thoughts

Python offers powerful tools for web development, APIs, and data visualization.
Would you like step-by-step projects on Flask, FastAPI, MkDocs, or Streamlit? 🚀