"""
Decorators to wrap functions to make them WSGI applications.
The main decorator :class:`wsgify` turns a function into a WSGI
application (while also allowing normal calling of the method with an
instantiated request).
"""
from webob.compat import (
bytes_,
text_type,
)
from webob.request import Request
from webob.exc import HTTPException
__all__ = ['wsgify']
class wsgify(object):
"""Turns a request-taking, response-returning function into a WSGI
app
You can use this like::
@wsgify
def myfunc(req):
return webob.Response('hey there')
With that ``myfunc`` will be a WSGI application, callable like
``app_iter = myfunc(environ, start_response)``. You can also call
it like normal, e.g., ``resp = myfunc(req)``. (You can also wrap
methods, like ``def myfunc(self, req)``.)
If you raise exceptions from :mod:`webob.exc` they will be turned
into WSGI responses.
There are also several parameters you can use to customize the
decorator. Most notably, you can use a :class:`webob.Request`
subclass, like::
class MyRequest(webob.Request):
@property
def is_local(self):
return self.remote_addr == '127.0.0.1'
@wsgify(RequestClass=MyRequest)
def myfunc(req):
if req.is_local:
return Response('hi!')
else:
raise webob.exc.HTTPForbidden
Another customization you can add is to add `args` (positional
arguments) or `kwargs` (of course, keyword arguments). While
generally not that useful, you can use this to create multiple
WSGI apps from one function, like::
import simplejson
def serve_json(req, json_obj):
return Response(json.dumps(json_obj),
content_type='application/json')
serve_ob1 = wsgify(serve_json, args=(ob1,))
serve_ob2 = wsgify(serve_json, args=(ob2,))
You can return several things from a function:
* A :class:`webob.Response` object (or subclass)
* *Any* WSGI application
* None, and then ``req.response`` will be used (a pre-instantiated
Response object)
* A string, which will be written to ``req.response`` and then that
response will be used.
* Raise an exception from :mod:`webob.exc`
Also see :func:`wsgify.middleware` for a way to make middleware.
You can also subclass this decorator; the most useful things to do
in a subclass would be to change `RequestClass` or override
`call_func` (e.g., to add ``req.urlvars`` as keyword arguments to
the function).
"""
RequestClass = Request
def __init__(self, func=None, RequestClass=None,
args=(), kwargs=None, middleware_wraps=None):
self.func = func
if (RequestClass is not None
and RequestClass is not self.RequestClass):
self.RequestClass = RequestClass
self.args = tuple(args)
if kwargs is None:
kwargs = {}
self.kwargs = kwargs
self.middleware_wraps = middleware_wraps
def __repr__(self):
return '<%s at %s wrapping %r>' % (self.__class__.__name__,
id(self), self.func)
def __get__(self, obj, type=None):
# This handles wrapping methods
if hasattr(self.func, '__get__'):
return self.clone(self.func.__get__(obj, type))
else:
return self
def __call__(self, req, *args, **kw):
"""Call this as a WSGI application or with a request"""
func = self.func
if func is None:
if args or kw:
raise TypeError(
"Unbound %s can only be called with the function it "
"will wrap" % self.__class__.__name__)
func = req
return self.clone(func)
if isinstance(req, dict):
if len(args) != 1 or kw:
raise TypeError(
"Calling %r as a WSGI app with the wrong signature" %
self.func)
environ = req
start_response = args[0]
req = self.RequestClass(environ)
req.response = req.ResponseClass()
try:
args, kw = self._prepare_args(None, None)
resp = self.call_func(req, *args, **kw)
except HTTPException as exc:
resp = exc
if resp is None:
## FIXME: I'm not sure what this should be?
resp = req.response
if isinstance(resp, text_type):
resp = bytes_(resp, req.charset)
if isinstance(resp, bytes):
body = resp
resp = req.response
resp.write(body)
if resp is not req.response:
resp = req.response.merge_cookies(resp)
return resp(environ, start_response)
else:
args, kw = self._prepare_args(args, kw)
return self.call_func(req, *args, **kw)
def get(self, url, **kw):
"""Run a GET request on this application, returning a Response.
This creates a request object using the given URL, and any
other keyword arguments are set on the request object (e.g.,
``last_modified=datetime.now()``).
::
resp = myapp.get('/article?id=10')
"""
kw.setdefault('method', 'GET')
req = self.RequestClass.blank(url, **kw)
return self(req)
def post(self, url, POST=None, **kw):
"""Run a POST request on this application, returning a Response.
The second argument (`POST`) can be the request body (a
string), or a dictionary or list of two-tuples, that give the
POST body.
::
resp = myapp.post('/article/new',
dict(title='My Day',
content='I ate a sandwich'))
"""
kw.setdefault('method', 'POST')
req = self.RequestClass.blank(url, POST=POST, **kw)
return self(req)
def request(self, url, **kw):
"""Run a request on this application, returning a Response.
This can be used for DELETE, PUT, etc requests. E.g.::
resp = myapp.request('/article/1', method='PUT', body='New article')
"""
req = self.RequestClass.blank(url, **kw)
return self(req)
def call_func(self, req, *args, **kwargs):
"""Call the wrapped function; override this in a subclass to
change how the function is called."""
return self.func(req, *args, **kwargs)
def clone(self, func=None, **kw):
"""Creates a copy/clone of this object, but with some
parameters rebound
"""
kwargs = {}
if func is not None:
kwargs['func'] = func
if self.RequestClass is not self.__class__.RequestClass:
kwargs['RequestClass'] = self.RequestClass
if self.args:
kwargs['args'] = self.args
if self.kwargs:
kwargs['kwargs'] = self.kwargs
kwargs.update(kw)
return self.__class__(**kwargs)
# To match @decorator:
@property
def undecorated(self):
return self.func
@classmethod
def middleware(cls, middle_func=None, app=None, **kw):
"""Creates middleware
Use this like::
@wsgify.middleware
def restrict_ip(req, app, ips):
if req.remote_addr not in ips:
raise webob.exc.HTTPForbidden('Bad IP: %s' % req.remote_addr)
return app
@wsgify
def app(req):
return 'hi'
wrapped = restrict_ip(app, ips=['127.0.0.1'])
Or as a decorator::
@restrict_ip(ips=['127.0.0.1'])
@wsgify
def wrapped_app(req):
return 'hi'
Or if you want to write output-rewriting middleware::
@wsgify.middleware
def all_caps(req, app):
resp = req.get_response(app)
resp.body = resp.body.upper()
return resp
wrapped = all_caps(app)
Note that you must call ``req.get_response(app)`` to get a WebOb
response object. If you are not modifying the output, you can just
return the app.
As you can see, this method doesn't actually create an application, but
creates "middleware" that can be bound to an application, along with
"configuration" (that is, any other keyword arguments you pass when
binding the application).
"""
if middle_func is None:
return _UnboundMiddleware(cls, app, kw)
if app is None:
return _MiddlewareFactory(cls, middle_func, kw)
return cls(middle_func, middleware_wraps=app, kwargs=kw)
def _prepare_args(self, args, kwargs):
args = args or self.args
kwargs = kwargs or self.kwargs
if self.middleware_wraps:
args = (self.middleware_wraps,) + args
return args, kwargs
class _UnboundMiddleware(object):
"""A `wsgify.middleware` invocation that has not yet wrapped a
middleware function; the intermediate object when you do
something like ``@wsgify.middleware(RequestClass=Foo)``
"""
def __init__(self, wrapper_class, app, kw):
self.wrapper_class = wrapper_class
self.app = app
self.kw = kw
def __repr__(self):
return '<%s at %s wrapping %r>' % (self.__class__.__name__,
id(self), self.app)
def __call__(self, func, app=None):
if app is None:
app = self.app
return self.wrapper_class.middleware(func, app=app, **self.kw)
class _MiddlewareFactory(object):
"""A middleware that has not yet been bound to an application or
configured.
"""
def __init__(self, wrapper_class, middleware, kw):
self.wrapper_class = wrapper_class
self.middleware = middleware
self.kw = kw
def __repr__(self):
return '<%s at %s wrapping %r>' % (self.__class__.__name__, id(self),
self.middleware)
def __call__(self, app=None, **config):
kw = self.kw.copy()
kw.update(config)
return self.wrapper_class.middleware(self.middleware, app, **kw)