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Name	Title
Space	Pylons CookBook
Section	Recipes
Page	A Pylons Controller with Trac as WSGI Callable
Version	1.0
Status	Draft
Curator	Walter Rodrigo de Sá Cruz
Reviewed	False
Author(s)	Walter Rodrigo de Sá Cruz

A Pylons controller with Trac as a WSGI callable

This tutorial shows a similar example from "A Pylons Controller with MoinMoin as WSGI Callable"

Introduction

This is a simple walk through of how to plug Trac into a Pylons controller.

Requirements are Pylons 0.9.4.1 (or later)

The Process

The four-step sequence is:

install Trac
create a new trac instance
add a Pylons trac controller and a route that maps to the trac instance.

install Trac

You can install by easy_install trac or using your Linux distribution package manager.

Create a new trac instance

trac-admin /var/trac/tracinstance initenv
I will ask you a lot of questions that you must answer.

Add a Pylons trac controller and a route that maps to the trac instance.

Create a new file: myproject/controllers/trac.py and add the following as its content (changing the two instances of myproject to your app's name):

from __future__ import absolute_import
from myproject.lib.base import *
from trac.web.main import dispatch_request
from authkit.permissions import NotAuthenticatedError
import os, StringIO, urllib

template = """\
  <html>
    <head><title>Please Login!</title></head>
    <body>
      <h1>Please Login</h1>
      <form action="" method="post">
        <dl>
          <dt>Username:</dt>
          <dd><input type="text" name="username"></dd>
          <dt>Password:</dt>
          <dd><input type="password" name="password"></dd>
        </dl>
        <input type="hidden" name="r" value="%s" />
        <input type="submit" name="authform" />
        <hr />
      </form>
    </body>
  </html>
"""

class TracController(BaseController):

    def tracpage(self, *args, **kwargs):
        # Thanks to ianbicking for a workaround of an empty wsgi.input value
        if request.environ.get('paste.parsed_formvars', False):
            wsgi_input = urllib.urlencode(
                request.environ['paste.parsed_formvars'][0], True)
            request.environ['wsgi.input'] = StringIO.StringIO(wsgi_input)
            request.environ['CONTENT_LENGTH'] = len(wsgi_input)

        os.environ['TRAC_ENV'] = "/var/trac/tracinstance"

        if request.environ['PATH_INFO'] == '/logout':
            del(session['user'])
            session.save()
            h.redirect_to('/')

        if request.environ['PATH_INFO'] == '/login' and not session.get('user'):
            #raise NotAuthenticatedError('Not Authenticated')
            return self._redirect_to_sign_in()

        if session.get('user'):
            request.environ['REMOTE_USER'] = session.get('user')
        a = dispatch_request(request.environ, self.start_response)
        if len(a) == 0:
            return ['']
        return a

    def _redirect_to_sign_in(self):
        if len(request.params) > 1 and request.params['password'] == request.params['username']:
            session['user'] = request.params['username']
            session.save()
            h.redirect_to('/')
        else:
            return Response(template)

Next, edit myproject/config/routing.py, adding the following route:

1	map.connect('trac/*path_info', controller='trac', action='tracpage', path_info='/')

Create the tree /trac/chrome/common inside the /public folder of your pylons application. Copy all the static content from trac to this folder (In my system, it's located at /usr/share/trac/htdocs).

The authentication that i'm using is a pretty simple: username == password.
And look that there's some problem using the authkit middleware.

The section:

a = dispatch_request(request.environ, self.start_response)
       if len(a) == 0:
           return ['']
       return a

looks weird. It's a workaround to 'No content returned from controller' that happens without it.

Check the results

Browse to [http://localhost:5000/trac/] and start using your trac inside pylons!

PylonsHQ.

A Pylons Controller with Trac as WSGI Callable