Simple URL shortener built with Pyramid (just for fun)

shortener.py

# -*- coding: utf-8 -*-
"""
Simple URL shortener built with Pyramid.

# Setup

## Dependencies
* pyramid>=1.5a3
* sqlalchemy>=0.9
* pyramid_tm
* zope.sqlalchemy
* gunicorn (or another WSGI container)

## Setup DB
python -c "from shortener import create_app, Base; a = create_app(); Base.metadata.create_all(a.registry.dbmaker().bind)"

# Run
gunicorn shortener
"""
import random
import string

from pyramid.config import Configurator
from pyramid.httpexceptions import HTTPFound, HTTPNotFound, HTTPPreconditionFailed
from pyramid.view import view_config
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from zope.sqlalchemy import ZopeTransactionExtension


# Model
Base = declarative_base()

class URL(Base):
    __tablename__ = 'urls'

    id = Column(Integer, primary_key=True)
    key = Column(String(10), unique=True)
    url = Column(String(255))

    @classmethod
    def generate_key(cls):
        return ''.join(random.choice(string.ascii_letters + string.digits) for x in range(10))


# Views
def get_url(request):
    key = request.matchdict.get('key')
    url = request.db.query(URL).filter_by(key=key).first()
    if url is None:
        raise HTTPNotFound()

    # TODO return would be better for the redirect
    raise HTTPFound(url.url)


def put_url(request):
    if 'url' not in request.json:
        raise HTTPPreconditionFailed()

    url = URL(key=URL.generate_key(), url=request.json['url'])
    request.db.add(url)
    return {'url': url.url, 'key': url.key}


def delete_url(request):
    key = request.matchdict.get('key')
    url = request.db.query(URL).filter_by(key=key).first()
    if url is None:
        raise HTTPNotFound()
    request.db.delete(url)
    return {}


def list_urls(request):
    urls = request.db.query(URL).all()
    return [{"key": u.key, "url": u.url, "href": request.route_url('url', key=u.key)} for u in urls]


# App
def create_app():
    cfg = Configurator()
    cfg.include('pyramid_tm')

    engine = create_engine('sqlite:///pyramidurlshortener.db')
    cfg.registry.dbmaker = sessionmaker(bind=engine, extension=ZopeTransactionExtension())

    def db(request):
        """db request method"""
        maker = request.registry.dbmaker
        session = maker()

        def cleanup(request):
            session.close()
        request.add_finished_callback(cleanup)

        return session

    cfg.add_request_method(db, reify=True)

    cfg.add_route('root', '/')
    cfg.add_view(list_urls, route_name='root', renderer='json', request_method='GET')
    cfg.add_view(put_url, route_name='root', renderer='json', request_method='PUT')

    cfg.add_route('url', '/{key}')
    cfg.add_view(get_url, route_name='url', request_method='GET')
    cfg.add_view(delete_url, route_name='url', renderer='json', request_method='DELETE')

    return cfg.make_wsgi_app()


application = create_app()