I have this piece of python code in gae.

def post(self):cases=self.request.get('cases')while cases:logging.info("cases: %s " % cases)case=cases.pop()

Which produces this log.

INFO     2012-09-19 20:23:50,690 views.py:674] cases: [u'court1150'] 
ERROR    2012-09-19 20:23:50,690 webapp2.py:1553] 'unicode' object has no attribute 'pop'
Traceback (most recent call last):File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1536, in __call__rv = self.handle_exception(request, response, e)File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1530, in __call__rv = self.router.dispatch(request, response)File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1278, in default_dispatcherreturn route.handler_adapter(request, response)File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 1102, in __call__return handler.dispatch()File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 572, in dispatchreturn self.handle_exception(e, self.app.debug)File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2/webapp2.py", line 570, in dispatchreturn method(*args, **kwargs)File "/Users/brian/googleapps/scheduler/views.py", line 675, in postcase=cases.pop()
AttributeError: 'unicode' object has no attribute 'pop'

On the other hand with this almost identical code in the interactive console.

cases = [u'court1150'] 
while cases:case=cases.pop()print case
print cases

I get no error and the following print out.

court1150
[]

Why am I getting a unicode error in the gae launcher and how can I fix it?

self.request.get('cases') does not return a list of values, it returns just one value. Try using get_all('cases') instead:

def post(self):cases=self.request.get_all('cases')while cases:logging.info("cases: %s " % cases)case=cases.pop()

There is no need to use a while loop, a for loop works much better:

def post(self):cases=self.request.get_all('cases')logging.info("cases: %s " % cases)for case in cases:# do something with case.