Varmkorv
Varmkorv is a CherryPy inspired micro framework using Werkzeug.
This is just a proof of concept. You are free to use it if you like, or find inspiration from it, or copy bits and pieces of it.
You might wonder if the world really need another Python web framework, and the answer is probably: no. I created this framework out of curiosity. The routes are "complied" (and recompiled if changed during runtime), and it does not contain much fluff at all. That makes this framework really speedy - way speedier than CherryPy (and Flask too for that matter).
I have implemented support for Authentication and Peewee. That is what I need for my personal projects, and might not suit all.
Hello, world!
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Hello, world!')
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
Point your browser to http://localhost:8080/ and feel welcomed.
Actions (views)
The example above contain just one route (or action, or view, or whatever name you use). Let's add a few more:
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Hello, world!')
def kebab(self, request: Request):
return Response('So nice')
def pizza(self, request: Request):
return Response('Also very nice')
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
We now have three routes:
http://localhost:8080/http://localhost:8080/kebabhttp://localhost:8080/pizza
Sub-controllers
If you are familiar with Flask, you probably know about Blueprints, but Varmkorv uses sub-controllers instead:
from varmkorv import Controller, App
from werkzeug import Request, Response
class Food(Controller):
def __call__(self, request: Request):
return Response('You got to eat')
def kebab(self, request: Request):
return Response('So nice')
def pizza(self, request: Request):
return Response('Also very nice')
class First(Controller):
def __call__(self, request: Request):
return Response('Hello, world!')
first = First()
first.food = Food()
app = App(first)
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
In this example we are creating an instance of Food and pass it as a the property food of First.
We now have these routes:
http://localhost:8080/http://localhost:8080/foodhttp://localhost:8080/food/kebabhttp://localhost:8080/food/pizza
Sub-controllers in __init__
from varmkorv import Controller, App
from werkzeug import Request, Response
class Food(Controller):
def __call__(self, request: Request):
return Response('You got to eat')
def kebab(self, request: Request):
return Response('So nice')
def pizza(self, request: Request):
return Response('Also very nice')
class First(Controller):
def __init__(self):
Controller.__init__(self)
self.food = Food()
def __call__(self, request: Request):
return Response('Hello, world!')
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
More on the properties of a controller
Every callable property of a controller that does not start with a _ (underscore) are treated as an action (or view, or whatever you want to call it).
Every property that inherits Controller that does not start with a _ is treated as a sub-controller. A sub-controller is also treated as an action (or view, and so on) if it's callable.
URL parameters
Let's create a very simple app:
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Good morning')
def hello(self, request: Request, name: str):
return Response('Hello, ' + name)
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
The hello action now has a mandatory name parameter.
http://localhost:8080/- Says "Good morning"http://localhost:8080/hello- Gives 404http://localhost:8080/hello/Gordon- Says "Hello, Gordon"
Optional parameters
And now, let's alter the code to support an optional name parameter instead:
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Good morning')
def hello(self, request: Request, name: str = None):
if not name:
return Response('Hello, mysterious person')
return Response('Hello, ' + name)
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
It's just as simple as adding = None to the definition.
Value error
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Good morning')
def user(self, request: Request, user_id: int):
user = User.find_or_none(User.id == user_id)
if not user:
return Response('Nobody')
return Response(user.name)
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
http://localhost:8080/hello- Gives 404http://localhost:8080/hello/123- Tells us the name of the userhttp://localhost:8080/hello/Gordon- Gives 404 because "Gordon" is not an integer
Custom data types
from varmkorv import Controller, App
from werkzeug import Request, Response
class Food(object):
def __init__(self, value):
if value == 'human':
raise ValueError;
self.value = value
class First(Controller):
def __call__(self, request: Request):
return Response('Good morning')
def food(self, request: Request, food: Food):
return Response(food.value + ' sounds good')
app = App(First())
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
http://localhost:8080/food/kebab- Says "kebab sounds good"http://localhost:8080/food/human- Gives 404
Peewee
from varmkorv import Controller, App, PeeweeWrapper
from werkzeug import Request, Response
from playhouse.apsw_ext import APSWDatabase
class First(Controller):
def __call__(self, request: Request, user_id: int):
user = User.find_or_none(User.id == user_id)
if not user:
return Response('Nobody')
return Response(user.name)
app = App(First())
db = APSWDatabase('my-food-website.db')
PeeweeWrapper(db).wrap_application(app)
from werkzeug.serving import run_simple
run_simple('localhost', 8080, app, use_reloader=True)
LoginManager
from varmkorv import Controller, App, PeeweeWrapper, LoginManager
from peewee import Model, AutoField, CharField
from playhouse.apsw_ext import APSWDatabase
class BaseModel(Model):
class Meta:
database = db
class User(BaseModel):
id = AutoField()
username = CharField()
password = CharField()
def verify_password(self, password):
# Verify the password. I recommend using passlib.
# I'll just return True here for the sake of it
# This method is not needed by LoginManager, but you probably need
# something similar
return True
def get_id(self):
# Return the id of the user. This one is needed by LoginManager
return str(self.id)
class First(Controller):
def login(self, request: Request):
username = request.form.get('username')
password = request.form.get('password')
user = User.find_or_none(User.username == username)
if not user or not user.verify_password(password):
return Response('Wrong username or password')
request.login.login_user(user)
return Response('Successfully logged in')
def check(self, request: Request):
if not request.login.user:
return Response('Not logged in')
return Response('Logged in as ' + request.login.user.username)
app = App(First())
db = APSWDatabase('my-food-website.db')
PeeweeWrapper(db).wrap_application(app)
def load_user(user_id):
return User.get_or_none(User.id == user_id)
login = LoginManager('secret', load_user)
login.wrap_application(app)
I am using Peewee in this example, but you are free to use whatever you like.
Feels like more work needs to be done on the LoginManager to make it more secure.
WSGI
Varmkorv is a WSGI application framework. You can for example run it using Meinheld:
from varmkorv import Controller, App
from werkzeug import Request, Response
class First(Controller):
def __call__(self, request: Request):
return Response('Hello, world!')
app = App(First())
from meinheld import server
server.listen(("127.0.0.1", 8080))
server.set_access_logger(None)
server.run(app)
Varmkorv will run under any WSGI server.
Things I have not written about yet
- on_request
- on_response
Things that are missing
As I said earlier, it feels like the LoginManager could get more secure.
There's no built in template engine, and I think it should stay like that. Maybe a wrapper for Jinja2 would be nice, though that probably works splendid stand alone (without a wrapper)
There's no configuration layer. I quite like Viper for Go. Not sure a built-in configuration layer is really needed though.
Varmkorv has the "on_request" and "on_response" hooks, but initially I had a different idea of how it should work. Here's some pseudo code (that looks awfully a lot like Python):
# A client defined method:
def hello(next):
def handle(request):
# stuff
response = next(request)
# things
return response
return handle
# And add it to the application
app.wrap(hello)
# Inside Varmkorv:
class App:
def wrap(self, func):
self.handle = func(self.handle)
This is sort of like Python decorators, but not using decorators. I guess decorators could actually be used.
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