Start of URL Shortener

gistfile1.py

import os 
import requests 
'''
url = self.request.get('url')
try:
    l = Link()
    l.seed(url)
except ValueError:
    self.render('index.html', error='Invalid Url')
'''
class Link(db.Model):
    url = db.LinkProperty(required=True)
    hash = db.StringProperty()
    created = db.DateTimeProperty(auto_now=False, auto_now_add=True)
    hits = db.IntegerProperty()

    def seed(self, url):
        if is_valid_url(url):
            self.url = url
            self.hash = generate_unique_hash()
            self.hits = 0
            self.put()
            return self
        else:
            raise ValueError('Invalid URL')
    
    
    def is_valid_url(url):
        r = requests.get(url)
        if r.status_code != 200:
            return False
        else:
            return True

    def generate_unique_hash(self):
        h = self.generate_hash()
        l = Link.all().filter("hash =", h)
        if h:
            return self.generate_unique_hash()
        else:
            return h
         
     def generate_hash(self):
        #returns random 16-bit string
        return os.urandom(2).encode('hex')