flask

Flask

Flask is a micro web framework. Flask is similar to Bottle, but it has more functionality out of the box and scales easier. Flask is better suited for larger projects that can span across multiple Python files.

Example

Say Hello

Let's create a simple server using Flask. This creates a server that says "Welcome to Flask!" when visiting the index page:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Welcome to Flask!'

if __name__ == '__main__':
    # host must be 0.0.0.0 to work in the Python3 IDE
    app.run(host='0.0.0.0', port=8080)

When we run our code, we get the folllowing output:

Basic Web Server with Templates

Flask will look for template files in the templates directory by default, so first, create a new folder named templates, then add a file named welcome.html.

To create a folder in your project, click on NEW FOLDER at the top of your project's file list:

Then, name it "templates" in the window that pops up:

Add a new file to your project and name it welcome.html. Paste the following HTML into the file, then put it inside of the templates folder that we just created:

<!DOCTYPE html>
<html>
    <head>
    </head>
    <body>
        Welcome to my website, {{name}}!
    </body>
</html>

Your project's file list should look like this when you are done:

Now that we have a template in our templates folder, copy and paste the below code to main.py:

from flask import Flask, render_template

app = Flask(__name__)

@app.route('/')
def index():
    return 'This is the index page'

@app.route('/welcome/<name>')
def welcome(name):
    return render_template(
        'welcome.html',
        name=name
    )

if __name__ == '__main__':
    # host must be 0.0.0.0 to work in the Python3 IDE
    app.run(host='0.0.0.0', port=8080)

When you visit "/", you will see a page like this:

And when you visit "/welcome/jane", you will see a page like this:

Reference

Flask at flask.palletsprojects.com