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Python Web Applications

By Zuhayer Quazi & Mihika Bairathi

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Why?

  • Python scripts are cool, but no one has any use for your .py file
  • Leaving ‘desktop’ based applications
  • Use python code to deliver dynamic content
  • All you need is an internet connection!

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Flask

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Flask

  • Python web-framework
  • Written after Django
  • Great for beginners
    • Also used in real, corporate life!
  • Extensive documentation
  • Built in development server/debugger

pip install flask

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Hello World

from flask import Flask

app = Flask(__name__)

@app.route("/")

def hello():

return "Hello World!"

if __name__ == "__main__":

app.run()

​

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URL Routes

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URL Routes

  • Make remembering URLs easier
  • google.com
    • /flights
    • /news
    • /gmail

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Routes

from flask import Flask

app = Flask(__name__)

@app.route("/")

def index():

return "Index!"

@app.route("/hello")

def hello():

return "Hello World!"

@app.route("/members")

def members():

return "Members"

@app.route("/members/<string:name>/")

def getMember(name):

return name

if __name__ == "__main__":

app.run()

​

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Structure

  • Project Name
    • templates
      • Templates for dynamically generated pages (generally .html pages)
    • static
      • Files that are not dynamically generated (css, images, etc)
    • app.py
      • Our application file!

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Templates!

  • Hello World goes in .html file!
    • Don’t put HTML in your app.py → no point, bad practice!
  • from flask import render_template
    • Render template will reach into the templates folder and find the HTML file you are referencing.

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Send Information

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Sending Information

  • Pass in parameters through render_template()

Add the following:

rest_count = 50

return render_template('index.html', count=rest_count)

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Hello, Z

from flask import Flask, render_template

app = Flask(__name__)

@app.route("/")

def index():

return "Flask App!"

@app.route("/hello/<string:name>/")

def hello(name):

return render_template('hello.html',name=name)

if __name__ == "__main__":

app.run()

​

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Make it look ‘prettier’

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More Variables

return render_template(___.html, **locals())

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Random Quote?

  • edit the html file to include {{quote}}
  • edit app.py to choose random quote!
  • From random import randint

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Next Steps

  • Adding more layers
    • Connecting templates together
  • Adding CSS
  • Making it DYNAMIC
    • Databases
    • MongoDB
    • SQL

​

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Requests

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HTTP - hypertext transfer protocol

  • Set of protocols that allows communication between client and servers
  • Web browser client, application/website is ‘server’
  • POST request
    • Send information to the server (when you login or register)
  • GET request
    • Request data from server (after you login!)
  • Use the `requests` library in Python

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Example

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Term Projects

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Personal Projects > Term Projects

  • We don’t recommend using web-apps for term projects.
  • Need approval from the professor(s) AND Arman.
    • They’ll be pretty strict
  • Make your own website
  • Hackathons
  • Get a job?!?!

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Questions?