mapproxy_filter.py

""" Minimal MapProxy Middleware demonstrating wrapping MapProxy and working
    with the query string

To run:
  1. Install MapProxy in a virtual enviroment together with Gunicorn
  2. Create a basic MapProxy config and copy this file into the same directory as mapproxy.yaml
  2. Activate virtual environment
  3. Change to the directory containing this file
  4. Run:
      gunicorn -k eventlet --workers=1 --log-file=- mapproxy_filter:application

"""

import urlparse
import urllib
from mapproxy.wsgiapp import make_wsgi_app


class RequestInfoFilter(object):
    """
    MapProxy middleware.

    Simply prints out the environment
    """
    def __init__(self, app):
        self.app = app

    def __call__(self, environ, start_response):

        qs = urlparse.parse_qs(environ['QUERY_STRING'], True)
        print 'Original querysting: %s' % qs

        # Manipulate the query string as required here...

        environ['QUERY_STRING'] = urllib.urlencode(qs, True)
        print 'Updated querysting passed to MapProxy: %s' % qs

        content = self.app(environ, start_response)
        return content


# Make an WSGI application and wrap it in the middleware
application = RequestInfoFilter(make_wsgi_app(r'mapproxy.yaml'))