Flask is a lightweight and versatile Python web framework that is perfect for beginners and experienced developers alike. It allows you to quickly create web applications in Python with minimal code and effort. In this tutorial, we will walk you through the basic concepts of Flask and show you how to create a simple web application using Flask.
What is Flask?
Flask is a web framework for Python that was created by Armin Ronacher. It is designed to be simple, easy to use, and extensible. Flask is based on the WSGI toolkit and Jinja2 templating engine, making it a powerful and flexible tool for developing web applications.
Flask is known for its simplicity and ease of use. It is a micro-framework, meaning that it has only the essentials needed to build web applications and does not have a lot of built-in functionality. This allows developers to have more control over their applications and to only include the features they need.
Installing Flask
Before you can start using Flask, you will need to install it on your system. You can install Flask using pip, the Python package installer. To install Flask, open a terminal window and type the following command:
pip install FlaskOnce Flask is installed, you can start creating web applications with it.
Creating a Flask Application
To create a new Flask application, you will need to create a Python file and import the Flask module. Here is an example of a simple Flask application:
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello_world():
return 'Hello, World!'
if __name__ == '__main__':
app.run()In this example, we create a new Flask application by importing the Flask module and creating a new Flask object called app. We then define a route using the @app.route decorator. This decorator tells Flask to call the hello_world function when the root URL is accessed. The hello_world function simply returns a string saying ‘Hello, World!’.
To run the Flask application, save the above code in a file called app.py and run it in a terminal window:
python app.pyYou should see a message saying that the Flask application is running. You can then open a web browser and navigate to http://localhost:5000 to see the ‘Hello, World!’ message displayed.
Adding Routes and Views
Flask uses routes to map URLs to Python functions, called views. Views are responsible for rendering HTML templates or returning data to the user. Here is an example of a Flask application with multiple routes and views:
from flask import Flask
app = Flask(__name__)
@app.route('/')
def index():
return 'Index Page'
@app.route('/about')
def about():
return 'About Page'
if __name__ == '__main__':
app.run()In this example, we have defined two routes: ‘/’ and ‘/about’. The index function is called when the root URL is accessed, and the about function is called when the ‘/about’ URL is accessed. Each function returns a different message to the user.
Adding Templates
Flask uses the Jinja2 templating engine to render HTML templates. Templates allow you to separate the presentation logic from the application logic, making your code more organized and easier to maintain. Here is an example of a Flask application using templates:
from flask import Flask, render_template
app = Flask(__name__)
@app.route('/')
def index():
return render_template('index.html')
if __name__ == '__main__':
app.run()In this example, we have modified the index function to render an HTML template called ‘index.html’. To use templates in Flask, you will need to create a new folder called ‘templates’ in the same directory as your Flask application. Inside the ‘templates’ folder, create a new file called ‘index.html’ with the following content:
<!DOCTYPE html>
<html>
<head>
<title>Flask Tutorial</title>
</head>
<body>
<h1>Welcome to Flask</h1>
<p>This is a simple Flask application.</p>
</body>
</html>When you run the Flask application and navigate to http://localhost:5000, you should see the contents of the ‘index.html’ template displayed in the browser.
Conclusion
Flask is a powerful and versatile web framework for Python that makes it easy to create web applications with minimal code and effort. In this tutorial, we have covered the basics of Flask and shown you how to create a simple web application using Flask. With its simplicity and flexibility, Flask is a great choice for developers of all skill levels.
Your feedback is truly important to me. So, bombarded me with your quires, questions, and criticism 😎. And, smash the like button 👍
I am using Windows…and gitbash while activating the environment it shows No such file or directory.
No bull****. Straight to the point. Well done
Very good
LFG
Why did you not just use "python -m venv myEnv"?
COVID is just a narrative. The shot is what's dangerous. No reason to stay home.
You should include 'part 1' in the video title, if your video is part of a series.
Wow, this is exactly what I needed. Thank you for the content, Pythonist!
Great explanation 👍
At 4:01 you say that you'll post a link to a written version of this tutorial, but I'm not seeing that link. Thanks in advance, if you can post that link.
Downvoted for the retarded covid suggestions.
Excellent
Your pronounciation is smooth and comprehensive. But a bit low compared to your sound effects.
Excellent! I like the fact that you actually defined what the parts are.
Very nice introductory video for Flask!
Short and to the point. Thank you!
Internal server error, please help
what a fantastic video…..thank you!!!
Hi, can I download the entire tutorial code somewhere like GitHub or so?