Get Started with Flask
Today we will talk about Flask.
What is Flask?
Flask is a lightweight WSGI web application framework in Python. It is designed to make getting started quickly and easily, with the ability to scale up to complex applications.
How to use Flask?
1. Create a project folder
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mkdir hello_world
cd hello_world
You can use script above to create a project folder hello_world.
2. Setup the Python virtual environment
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python3 -m venv .venv
source .venv/bin/activate
Create Python virtual environment using python3 -m venv .venv and activate it using source .venv/bin/activate.
By the way, you can exit from the Python virtual environment using
deactivate.
3. Install Flask
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pip install Flask
Run the script to install Flask module.
4. Write your application
Write your code inside a Python file named app.py.
You can use any name for your Python file.
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# app.py
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello_world():
return "<p>Hello, World!</p>"
- First, we imported the
Flaskclass at line 2. An instance of this class will be our WSGI application. - We created an instance of
Flasknamedappat line 4. The first argument is the name of the application’s module or package. - We then used the
route()decorator to tell Flask what URL should trigger our function at line 6. - The function
hello_worldreturned the HTML message.
5. Test the application
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flask run
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* Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
Since I used
app.py, I can run the application usingflask rundirectly. If you used other names, you may need to specify where your application is usingflask --app hello run(hello.py). You can check here for more details.
Now open the link (http://127.0.0.1:5000) in your browser, you can see Hello, World!.