This chapter will cover the basics of Jinja2 templating from the perspective of Flask; we will also learn how to make applications with modular and extensible templates.
In Flask, we can write a complete web application without the need for third-party templating engine. For example, have a look at the following code; this is a standalone, simple Hello World application with a bit of HTML styling included:
from flask import Flask 
app = Flask(__name__) 
 
@app.route('/') 
@app.route('/hello') 
@app.route('/hello/<user>') 
def hello_world(user=None): 
    user = user or 'Shalabh' 
    return ''' 
<html> 
    <head> 
      <title>Flask Framework Cookbook</title> 
 
    </head> 
      <body> 
        <h1>Hello %s!</h1> 
        <p>Welcome to the... 
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
     
         
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
                