First create a specific python file to hold your custom filters at the root of your application. In my case I use customfilters.py like this:

import re
from google.appengine.ext import webapp
 
register = webapp.template.create_template_register()
 
def escapeimg(body):
	return re.sub(r'

', '[IMG]', body)
 
register.filter(escapeimg)

Then in your main application source file, call the following line outside of the main() definition, for example just after your modules loading:

"""Load custom Django template filters"""
webapp.template.register_template_library('customfilters')

You should then be able to use the new filters you registered in customfilters.py straight away in any of your Django templates without any % load foobar % call

import cgi
import urllib
from google.appengine.ext import webapp
from google.appengine.api import urlfetch
 
class FlickrController(webapp.RequestHandler):
	"""Proxy for Ajax calls to flickr"""
	def get(self):
		flickrapiendpoint = 'http://api.flickr.com/services/rest/'
		flickrapikey = 'you_flicker_api_key'
 
		params = self.request.GET
		params.add('api_key', flickrapikey)
		params.add('format', 'json')
		apiquery = urllib.urlencode(params)
 
		result = urlfetch.fetch(url=flickrapiendpoint + '?' + apiquery, method=urlfetch.GET)
		self.response.out.write(result.content)
 
def main():
	application = webapp.WSGIApplication(
		[('/flickr/', FlickrController)],
		debug=True)
	wsgiref.handlers.CGIHandler().run(application)
 
if __name__ == "__main__":
	main()

I didn't see examples of such a script anywhere else so I thought I'd post it here for all to see.

I love to stumble on those constant little UI and usability improvements that make you wonder if they were there yesterday. It's brilliant.