flask intro

jongho kim

Flask is Microframework

Jinja2 = templating language for Python

Werkzeug = Python WSGI Utility Library

Flask = Jinja2 + Werkzeug

Jinja2 

Jinja2 can generate any text-based format(HTML, XML etc)

A template contains variables or expressions, which get replaced with values when the template is evaluated, and tags, which control the logic of the template

 users = [  {"url" : "http://daum.net", "username" : "jonghokim"},  {"url" : "http://naver.com", "username" : "moonsookim"}]

WSGI

Browser: IE, Chrome, Firefox, etc...

Server : Apache, Nginx, etc...

App : Django, Flask, etc...

WSGI는 Server와 App이 통신하는 명세이다.

WerkZeug(2)

WerkZeug : WSGI Library. not FrameWork.

WSGI itself is a protocol or convention that ensures that your web application can speak with the webserver. [PEP333]

[without WerkZeug - start_response in 'python']

[WerkZeug]

Werkzeug(2) -  출처 : http://spoqa.github.io/2012/01/16/wsgi-and-flask.html

environ : Python dictionary - HTTP(RFC2616)요청을 처리하는데 필요한 정보가 들어있다.

Werkzeug의 기능

• Request / Response Object
• URL Routing
• HTTP Utilities
• Middleware
• etc...

Werkzeug(3) - Middleware

Middleware에는 어떤 것들이? - WSGI명세에 없지만 필요한 기능들이  들어간다.

• Cookie
• Session
• SecureCookie
• etc ...

Flask = Jinja2 + Werkzeug

app = Flask(__name__) #app을 인스턴스화@app.route("/") #URL Route - "localhost:5000/"에 접속하면 아래 def 실행@ -> decorator 파이썬 Syntax중 하나app.run()으로 실행 

Flask Extensions

Flask is microframework.

So, we need Flask-Extensions (http://flask.pocoo.org/extensions/)

• Flask-Sqlalchemy (ORM, database)
• Flask-login (Login)
• Flask-WTF (Form validation)
• Flask-OAuth (for facebook, twitter)
• Flask-Celery (Distributed Task Queue)
• etc...

Flask project simulation

source - https://github.com/mitsuhiko/flask/tree/master/examples/flaskr