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Getting Started with Flask

A comprehensive introduction to Flask

Flask is a lightweight and popular Python web framework that makes it easy to build web applications. In this presentation, I'll provide you with an overview of Flask, its key features, and some coding samples to help you get started.

Getting Started with Flask - Tutorial provided by AppSeed

✅ What is Flask

  • Flask is a micro web framework for Python.
  • It's designed to be simple, lightweight, and easy to use.
  • Flask provides the essentials for building web applications without imposing too much structure or complexity.

✅ Key Features of Flask


Flask doesn't include a lot of built-in functionality, allowing you to choose and integrate the components you need for your project.


Define URL routes and map them to Python functions for handling requests.

HTTP Methods

Easily handle HTTP methods (GET, POST, PUT, DELETE, etc.) for different routes.


Flask includes a templating engine (Jinja2) for rendering HTML templates.

Web Forms

Flask-WTF and other extensions make it easy to work with web forms and user input.

Database Support

Integration with various databases (SQLAlchemy, SQLite, etc.) for data storage.


A rich ecosystem of extensions for adding functionality like authentication, API development, and more.

RESTful API Support

Flask can be used to build RESTful APIs for serving data.

Development Server

Comes with a built-in development server for testing your application locally.

Easy to Learn

Flask's simplicity makes it a great choice for beginners.

✅ Code Sample

Let's look at some basic Flask code samples to get a feel for how it works.

1. Hello, World!

from flask import Flask

app = Flask(__name__)

def hello():
return "Hello, World!"

if __name__ == "__main__":
  • This code defines a Flask application and a single route (/) that returns "Hello, World!" when accessed in a web browser.

2. Routing and Dynamic URLs

def user_profile(username):
return f"User Profile: {username}"
  • Here, we define a dynamic route that captures a username from the URL and displays it.

3. Templates and Rendering HTML

from flask import render_template

def hello_name(name):
return render_template("hello.html", name=name)
  • Flask uses Jinja2 templates to render HTML. In this example, we render an HTML template with a dynamic name variable.

4. Handling Forms

from flask import Flask, render_template, request

@app.route("/submit", methods=["POST"])
def submit_form():
if request.method == "POST":
username = request.form.get("username")
return f"Form submitted with username: {username}"
return "Invalid request method"

This code handles form submissions and extracts data from the POST request.

✅ In Summary

Flask is a versatile and easy-to-learn web framework for building web applications and APIs in Python. Its simplicity and flexibility make it a great choice for a wide range of projects.

To dive deeper into Flask, explore its documentation ( and consider exploring extensions and advanced topics like authentication, database integration, and deployment.

✅ Resources