Getting Started

Flask is the best micro web framework written in Python 🔥

Installation

$ pip install -U flask

• Open your favourite code editor 😍
• Create a new *.py file ✅
• Import Flask from the flask framework and define your app:

from flask import Flask

app = Flask(__name__)

• __name__ is the import name for our flask app

Create simple view function that returns simple text/html response:

from flask import Flask


app = Flask(__name__)


def home_view():
    return "Hello Bro 👋"

Next, you will should add this view function on your app's url rules. For this, we have to use Flask's add_url_rule method:

from flask import Flask


app = Flask(__name__)


def home_view():
    return "Hello Bro 👋"


app.add_url_rule(
    rule="/",
    view_func=home_view
)

flask.Flask.add_url_rule

• rule should be str
• view should be function or class For class based views, Flask has as_view method.

Routes

The method of add_url_rule is used by flask developers very rarely. They use route decorator instead of using add_url_rule and it provides to assign URLs in our app to functions easily.

@app.route("/")
def home_view():
    return "Hello Bro 👋"

• "/" - url that our view function returns response.

route decorator also uses from add_url_rule method :

From flask's source code

You can return any of the string and binary related types: str, unicode , bytes , bytearray, or if you prefer, you can return an already built response object:

from flask import Response

app = Flask(__name__)

@app.route("/")
def function():
    return Response(...)

View Functions

The names we chose for our view functions should be unique.

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

@app.route("/home")
def home():
    return "Hello from home_2!"

# AssertionError:
# View function mapping is overwriting an existing endpoint function: :view_function_name: