.. _tutorials.gettingstarted.handlingforms:
Handling Forms with webapp2
===========================
If we want users to be able to post their own greetings, we need a way to
process information submitted by the user with a web form. The ``webapp2``
framework makes processing form data easy.
Handling Web Forms With webapp2
-------------------------------
Replace the contents of ``helloworld/helloworld.py`` with the following::
import cgi
from google.appengine.api import users
import webapp2
class MainPage(webapp2.RequestHandler):
def get(self):
self.response.out.write("""
""")
class Guestbook(webapp2.RequestHandler):
def post(self):
self.response.out.write('You wrote:')
self.response.out.write(cgi.escape(self.request.get('content')))
self.response.out.write('')
application = webapp2.WSGIApplication([
('/', MainPage),
('/sign', Guestbook)
], debug=True)
def main():
application.run()
if __name__ == "__main__":
main()
Reload the page to see the form, then try submitting a message.
This version has two handlers: ``MainPage``, mapped to the URL ``/``, displays
a web form. ``Guestbook``, mapped to the URL ``/sign``, displays the data
submitted by the web form.
The ``Guestbook`` handler has a ``post()`` method instead of a ``get()``
method. This is because the form displayed by ``MainPage`` uses the HTTP POST
method (``method="post"``) to submit the form data. If for some reason you
need a single handler to handle both GET and POST actions to the same URL, you
can define a method for each action in the same class.
The code for the ``post()`` method gets the form data from ``self.request``.
Before displaying it back to the user, it uses ``cgi.escape()`` to escape
HTML special characters to their character entity equivalents. ``cgi`` is a
module in the standard Python library; see `the documentation for cgi `_
for more information.
.. note::
The App Engine environment includes the entire Python 2.5 standard library.
However, not all actions are allowed. App Engine applications run in a
restricted environment that allows App Engine to scale them safely.
For example, low-level calls to the operating system, networking operations,
and some filesystem operations are not allowed, and will raise an error
when attempted. For more information, see `The Python Runtime Environment `_.
Next...
-------
Now that we can collect information from the user, we need a place to put it
and a way to get it back.
Continue to :ref:`tutorials.gettingstarted.usingdatastore`.