""" Copyright (c) 2008, appengine-utilities project All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name of the appengine-utilities project nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. """ import os import sys import Cookie import pickle from time import strftime from django.utils import simplejson COOKIE_NAME = 'appengine-utilities-flash' class Flash(object): """ Send messages to the user between pages. When you instantiate the class, the attribute 'msg' will be set from the cookie, and the cookie will be deleted. If there is no flash cookie, 'msg' will default to None. To set a flash message for the next page, simply set the 'msg' attribute. Example psuedocode: if new_entity.put(): flash = Flash() flash.msg = 'Your new entity has been created!' return redirect_to_entity_list() Then in the template on the next page: {% if flash.msg %} <div class="flash-msg">{{ flash.msg }}</div> {% endif %} """ def __init__(self, cookie=None): """ Load the flash message and clear the cookie. """ self.no_cache_headers() # load cookie if cookie is None: browser_cookie = os.environ.get('HTTP_COOKIE', '') self.cookie = Cookie.SimpleCookie() self.cookie.load(browser_cookie) else: self.cookie = cookie # check for flash data if self.cookie.get(COOKIE_NAME): # set 'msg' attribute cookie_val = self.cookie[COOKIE_NAME].value # we don't want to trigger __setattr__(), which creates a cookie try: self.__dict__['msg'] = simplejson.loads(cookie_val) except: # not able to load the json, so do not set message. This should # catch for when the browser doesn't delete the cookie in time for # the next request, and only blanks out the content. pass # clear the cookie self.cookie[COOKIE_NAME] = '' self.cookie[COOKIE_NAME]['path'] = '/' self.cookie[COOKIE_NAME]['expires'] = 0 print self.cookie[COOKIE_NAME] else: # default 'msg' attribute to None self.__dict__['msg'] = None def __setattr__(self, name, value): """ Create a cookie when setting the 'msg' attribute. """ if name == 'cookie': self.__dict__['cookie'] = value elif name == 'msg': self.__dict__['msg'] = value self.__dict__['cookie'][COOKIE_NAME] = simplejson.dumps(value) self.__dict__['cookie'][COOKIE_NAME]['path'] = '/' print self.cookie else: raise ValueError('You can only set the "msg" attribute.') def no_cache_headers(self): """ Adds headers, avoiding any page caching in the browser. Useful for highly dynamic sites. """ print "Expires: Tue, 03 Jul 2001 06:00:00 GMT" print strftime("Last-Modified: %a, %d %b %y %H:%M:%S %Z") print "Cache-Control: no-store, no-cache, must-revalidate, max-age=0" print "Cache-Control: post-check=0, pre-check=0" print "Pragma: no-cache"