Flask

__ name __ : Special variable of python. Just the name of module. __ name __ = __ main__ for the following code

from flask import Flask
app = Flask(__name__)

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

Routes

routes are what we type into our browser to go to different pages.

Run The Application (command prompt )

At first need to set environment variable

set FLASK_APP=flaskblog.py

to run the application

flask run

to stop the application ctrl+c

In this way the application need to run again and again if any change happens. And to avoid this need to run in DEBUG mood. for this need to set a different environment variable

set FLASK_DEBUG=1

Another way to run application directly with python and get rid of those environment variable.

add the following code end of the main file

if __name__ == '__main__':
    app.run(debug=True)

and in command line just run the main file as trivial python file.

python flaskblog.py

Adding extra pages

in the main.py(flaskblog.py) page add extra route

@app.route("/about")

Adding multiline html(naive approach)

def home():
    return '''
    <!doctype html>
    <html>
        <head> <title> Home </title> </head>
        <body> Hey! </body>
    </html>
    '''

Adding multiline html(Smart approach)

make a templates folder.
create html pages.
in main.py import render_templates
render the page like the following code

def home():
    return render_template('home.html')

Passing Data

pass the data variable with render

def home():
    return render_template('home.html', posts = posts)

access the data like following

 {% for post in posts%}
        <h1>Hey {{ post.author }}!</h1>
 {% endfor %}

Template Inheritance

To ignore changing each and every pages for a specific part should use a layout file so if any change needed only changing the layout page will do.

make a new page layout.html
and the common code lines to the page
add block where changes required for different pages

<body>
    {% block content %}{% endblock %}
</body>

Change the previous files like the following one

{% extends "layout.html" %}
{% block content %}
    <h1>Hey!</h1>
{% endblock content%}

can also add bootstrap in layout page.

Adding CSS

CSS files need to be kept in a static folder named "static"
add new css file to that folder.
to add this css file to layout need to use a flask function - url_for. This function will found the exact location of the routes so no need to worry about it in background.
import the url_for function in main.py(flaskblog.py) file.

Learning Buffer

Route Decorator

FatimaTasnim/Flask-Toy-Project