Ticket #455: app_with_middleware.py

"""This example requires EvalException from Paste and
Allan Saddi's session middleware.
"""

import sys

import cherrypy

try:
    from paste.evalexception.middleware import EvalException
    from paste.lint import middleware as lint_middleware
except ImportError:
    print "Please install paste 0.4.2 or the latest Paste development code."
    print "(hint: easy_install -U Paste==dev)"
    sys.exit(1)
try: 
    from session import SessionMiddleware, MemorySessionStore
except ImportError:
    print """The middleware session example is only available with
    Alan Saddi's session middlware on your python path.
    http://www.saddi.com/software/py-lib/#Session
    """
    sys.exit(1)

# wrapper for session middleware
def session_middleware(app, store=None):
    return SessionMiddleware(store, app)

class Root(object):
    @cherrypy.expose
    def index(self):
        yield "Some things are cool and some things are awesome<br>"
        yield "Get in <a href='/problem'>trouble</a><br>"
        yield "Middleware <a href='tracker'>sessions</a><br>"
        yield cherrypy.request.browser_url + '<br>'
        yield cherrypy.request.path + '<br>'
        yield cherrypy.request.object_path + '<br>'

    @cherrypy.expose
    def problem(self):
        "error on purpose to show off EvalException"
        assert 0, "Houston, we have a problem."

    @cherrypy.expose
    def tracker(self):
        env = cherrypy.request.wsgi_environ.get
        session = env('com.saddi.service.session').session
        count = session.get('count', 0) + 1
        session['count'] = count
        return "You have been here %s times." % count

# we need this so that errors trickle down to the middleware
cherrypy.config.update({'server.throw_errors':True})

# mount our CherryPy apps
cherrypy.root = Root()
cherrypy.root.toor = Root()

# create our middleware "stack"
# (a list of middleware that will chain together with
# each other and finally CP
mw = [(EvalException, {'global_conf':dict()}),
      # there is a problem with [wsgi.input] in CP that lint hangs on
      # (lint_middleware, {}),
      (session_middleware, {'store':MemorySessionStore()}),
      ]

# start the server with the middleware stack
cherrypy.server.start(middleware=mw)