PasteEvalException

== Using the Paste !EvalException middleware with CherryPy ==

When developing you application you may want to inspect in details the exception or error traceback, [http://pythonpaste.org/ Paste] provides the [http://pythonpaste.org/class-paste.evalexception.middleware.EvalException.html evalexception] module which comes with a set of WSGI middleware to perform advances debugging tasks. !CherryPy let you use this module and benefit from its features. Below is a basi example on how to set it up.

{{{
#!python
import cherrypy
from paste import evalexception
from paste.httpexceptions import *

class Root:
    @cherrypy.expose
    def index(self):
        raise HTTPBadRequest("you're doomed mate.")
    
    @cherrypy.expose
    def hello(self):
        raise cherrypy.HTTPError, "aaaaaaaaaaaah"

if __name__ == '__main__':
    cherrypy.config.update({'global':{'request.throw_errors': True,
                                      'log.screen': True,
                                      'engine.autoreload_on': False}})
    # Create a WSGI application
    app = cherrypy.Application(Root())
    app.wsgiapp.pipeline.append(('paste_exc', evalexception.middleware.EvalException))
    cherrypy.quickstart(app)
}}} 

 1. Set the {{{request.throw_errors}}} to {{{True}}}. This will prevent !CherryPy to handle the exception itself.
 2. Add the {{{evalexception.middleware.EvalException}}} to the application pipeline of WSGI middlewares.

Et voilà.

For more on using the WSGI pipeline in CherryPy, see [http://cherrypy.org/wiki/WSGI#UsingWSGImiddlewarewithCherryPy the official documentation].