Question

I’m trying Google AppEngine and Python today for the first time and managed to get a simple example running. It worked but something wierd is happening: when a URL parameter value changes, it’s not registered unless I restart the app.

In my example below, if I run: http://localhost:8080/?x=hello it will return ‘x is hello’ as it should but if I change the value of X, its new value does not affect the output.

I suspect there is some kind of internal caching going on, but I’m not sure.

from google.appengine.ext import webapp
from google.appengine.ext.webapp import util

import cgi
form = cgi.FieldStorage()
x = form.getvalue('x')

class MainHandler(webapp.RequestHandler):
    def get(self):
        if x == 'hello':
            self.response.out.write('x is hello')
        else:
            self.response.out.write('x is not hello')

def main():
    application = webapp.WSGIApplication([('/', MainHandler)],
                                         debug=True)
    util.run_wsgi_app(application)


if __name__ == '__main__':
    main()

Answer 1

You’re getting the form value outside the handler, in the module-level code. Obviously, that is defined when the module is first loaded, at the time of the first request. You should be doing that inside the get method.