webob.dec – WSGIfy decorator

Decorators to wrap functions to make them WSGI applications.

The main decorator wsgify turns a function into a WSGI application (while also allowing normal calling of the method with an instantiated request).

Decorator

class webob.dec.wsgify(func=None, RequestClass=None, args=(), kwargs=None, middleware_wraps=None)

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 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 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 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 webob.exc

Also see 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

alias of Request

call_func(req, *args, **kwargs)

Call the wrapped function; override this in a subclass to change how the function is called.

clone(func=None, **kw)

Creates a copy/clone of this object, but with some parameters rebound

get(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')
classmethod middleware(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).

post(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'))
request(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')