"city": "Default City",

"maxAttendees": 0,

"seatsAvailable": 0,

"topics": ["Default", "Topic"],

'EQ': '=',

'GT': '>',

'GTEQ': '>=',

'LT': '<',

'LTEQ': '<=',

'NE': '!='

'CITY': 'city',

'TOPIC': 'topics',

'MONTH': 'month',

'MAX_ATTENDEES': 'maxAttendees',

"""Conference API v0.1"""

# - - - Conference objects - - - - - - - - - - - - - - - - -

def _copyConferenceToForm(self, conf, displayName):

"""Copy relevant fields from Conference to ConferenceForm."""

cf = ConferenceForm()

for field in cf.all_fields():

if hasattr(conf, field.name):

# convert Date to date string; just copy others

if field.name.endswith('Date'):

setattr(cf, field.name, str(getattr(conf, field.name)))

else:

setattr(cf, field.name, getattr(conf, field.name))

elif field.name == "websafeKey":

setattr(cf, field.name, conf.key.urlsafe())

if displayName:

setattr(cf, 'organizerDisplayName', displayName)

cf.check_initialized()

return cf

def _createConferenceObject(self, request):

"""Create or update Conference object, returning

ConferenceForm/request."""

# preload necessary data items

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

if not request.name:

raise endpoints.BadRequestException(

"Conference 'name' field required")

# copy ConferenceForm/ProtoRPC Message into dict

data = {field.name: getattr(request, field.name)

for field in request.all_fields()}

del data['websafeKey']

del data['organizerDisplayName']

# add default values for those missing (both data model & outbound

# Message)

for df in DEFAULTS:

if data[df] in (None, []):

data[df] = DEFAULTS[df]

setattr(request, df, DEFAULTS[df])

# convert dates from strings to Date objects; set month based on

# start_date

if data['startDate']:

data['startDate'] = datetime.strptime(data['startDate'][:10],

"%Y-%m-%d").date()

data['month'] = data['startDate'].month

else:

data['month'] = 0

if data['endDate']:

data['endDate'] = datetime.strptime(data['endDate'][:10],

"%Y-%m-%d").date()

# set seatsAvailable to be same as maxAttendees on creation

if data["maxAttendees"] > 0:

data["seatsAvailable"] = data["maxAttendees"]

# generate Profile Key based on user ID and Conference

# ID based on Profile key get Conference key from ID

p_key = ndb.Key(Profile, user_id)

c_id = Conference.allocate_ids(size=1, parent=p_key)[0]

c_key = ndb.Key(Conference, c_id, parent=p_key)

data['key'] = c_key

data['organizerUserId'] = request.organizerUserId = user_id

# create Conference, send email to organizer confirming

# creation of Conference & return (modified) ConferenceForm

print(Conference(**data).put().urlsafe()) # for debugging

# Conference(**data).put().urlsafe() # for production

taskqueue.add(params={'email': user.email(),

'conferenceInfo': repr(request)},

url='/tasks/send_confirmation_email')

return request

@ndb.transactional()

def _updateConferenceObject(self, request):

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

# copy ConferenceForm/ProtoRPC Message into dict

data = {field.name: getattr(request, field.name)

for field in request.all_fields()}

# update existing conference

conf = ndb.Key(urlsafe=request.inputString).get()

# check that conference exists

if not conf:

raise endpoints.NotFoundException(

'No conference found with key: %s' % request.inputString)

# check that user is owner

if user_id != conf.organizerUserId:

raise endpoints.ForbiddenException(

'Only the owner can update the conference.')

# Not getting all the fields, so don't create a new object; just

# copy relevant fields from ConferenceForm to Conference object

for field in request.all_fields():

data = getattr(request, field.name)

# only copy fields where we get data

if data not in (None, []):

# special handling for dates (convert string to Date)

if field.name in ('startDate', 'endDate'):

data = datetime.strptime(data, "%Y-%m-%d").date()

if field.name == 'startDate':

conf.month = data.month

# write to Conference object

setattr(conf, field.name, data)

print(conf.put().urlsafe()) # For debugging

# conf.put() # For production

prof = ndb.Key(Profile, user_id).get()

return self._copyConferenceToForm(conf, getattr(prof, 'displayName'))

@endpoints.method(ConferenceForm,

ConferenceForm,

path='conference',

http_method='POST',

name='createConference')

def createConference(self, request):

"""Create new conference."""

return self._createConferenceObject(request)

@endpoints.method(CONF_POST_REQUEST,

ConferenceForm,

path='conference/{inputString}',

http_method='PUT',

name='updateConference')

def updateConference(self, request):

"""Update conference w/provided fields & return w/updated info."""

return self._updateConferenceObject(request)

@endpoints.method(GET_OR_DELETE_REQUEST,

ConferenceForm,

path='conference/{inputString}',

http_method='GET',

name='getConference')

def getConference(self, request):

"""Return requested conference (by inputString)."""

# get Conference object from request; bail if not found

conf = ndb.Key(urlsafe=request.inputString).get()

if not conf:

raise endpoints.NotFoundException(

'No conference found with key: %s' % request.inputString)

prof = conf.key.parent().get()

# return ConferenceForm

return self._copyConferenceToForm(conf, getattr(prof, 'displayName'))

@endpoints.method(message_types.VoidMessage,

ConferenceForms,

path='getConferencesCreated',

http_method='POST',

name='getConferencesCreated')

def getConferencesCreated(self, request):

"""Return conferences created by user."""

# make sure user is authed

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

# create ancestor query for all key matches for this user

confs = Conference.query(ancestor=ndb.Key(Profile, user_id))

prof = ndb.Key(Profile, user_id).get()

# return set of ConferenceForm objects per Conference

return ConferenceForms(items=[self._copyConferenceToForm(conf, getattr(

prof, 'displayName')) for conf in confs])

def _getQuery(self, request):

"""Return formatted query from the submitted filters."""

q = Conference.query()

inequality_filter, filters = self._formatFilters(request.filters)

# If exists, sort on inequality filter first

if not inequality_filter:

q = q.order(Conference.name)

else:

q = q.order(ndb.GenericProperty(inequality_filter))

q = q.order(Conference.name)

for filtr in filters:

if filtr["field"] in ["month", "maxAttendees"]:

filtr["value"] = int(filtr["value"])

formatted_query = ndb.query.FilterNode(

filtr["field"], filtr["operator"], filtr["value"])

q = q.filter(formatted_query)

return q

def _formatFilters(self, filters):

"""Parse, check validity and format user supplied filters."""

formatted_filters = []

inequality_field = None

for f in filters:

filtr = {field.name: getattr(f, field.name)

for field in f.all_fields()}

try:

filtr["field"] = FIELDS[filtr["field"]]

filtr["operator"] = OPERATORS[filtr["operator"]]

except KeyError:

raise endpoints.BadRequestException(

"Filter contains invalid field or operator.")

# Every operation except "=" is an inequality

if filtr["operator"] != "=":

# check if inequality operation has been used in previous

# filters disallow the filter if inequality was performed on a

# different field before track the field on which the

if inequality_field and inequality_field != filtr["field"]:

raise endpoints.BadRequestException(

"Inequality filter is allowed on only one field.")

else:

inequality_field = filtr["field"]

formatted_filters.append(filtr)

return (inequality_field, formatted_filters)

@endpoints.method(ConferenceQueryForms,

ConferenceForms,

path='queryConferences',

http_method='POST',

name='queryConferences')

def queryConferences(self, request):

"""Query for conferences."""

conferences = self._getQuery(request)

# need to fetch organiser displayName from profiles

# get all keys and use get_multi for speed

organisers = [(ndb.Key(Profile, conf.organizerUserId))

for conf in conferences]

profiles = ndb.get_multi(organisers)

# put display names in a dict for easier fetching

names = {}

for profile in profiles:

names[profile.key.id()] = profile.displayName

# return individual ConferenceForm object per Conference

return ConferenceForms(items=[self._copyConferenceToForm(conf, names[

conf.organizerUserId]) for conf in conferences])

# - - - Profile objects - - - - - - - - - - - - - - - - - - -

def _copyProfileToForm(self, prof):

"""Copy relevant fields from Profile to ProfileForm."""

# copy relevant fields from Profile to ProfileForm

pf = ProfileForm()

for field in pf.all_fields():

if hasattr(prof, field.name):

# convert t-shirt string to Enum; just copy others

if field.name == 'teeShirtSize':

setattr(pf, field.name, getattr(TeeShirtSize,

getattr(prof, field.name)))

else:

setattr(pf, field.name, getattr(prof, field.name))

pf.check_initialized()

return pf

def _getProfileFromUser(self):

"""Return user Profile from datastore, creating new one if

non-existent."""

# make sure user is authed

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

p_key = ndb.Key(Profile, user_id)

profile = p_key.get()

# create new Profile if not there

if not profile:

profile = Profile(key=p_key,

displayName=user.nickname(),

mainEmail=user.email(),

teeShirtSize=str(TeeShirtSize.NOT_SPECIFIED), )

print(profile.put().urlsafe()) # for debugging

# profile.put() # for production

return profile # return Profile

def _doProfile(self, save_request=None):

"""Get user Profile and return to user, possibly updating it first."""

# get user Profile

prof = self._getProfileFromUser()

# if saveProfile(), process user-modifyable fields

if save_request:

for field in ('displayName', 'teeShirtSize'):

if hasattr(save_request, field):

val = getattr(save_request, field)

if val:

setattr(prof, field, str(val))

# if field == 'teeShirtSize':

# setattr(prof, field, str(val).upper())

# else:

# setattr(prof, field, val)

print(prof.put().urlsafe()) # for debugging

# prof.put() # for productiong

# return ProfileForm

return self._copyProfileToForm(prof)

@endpoints.method(message_types.VoidMessage,

ProfileForm,

path='profile',

http_method='GET',

name='getProfile')

def getProfile(self, request):

"""Return user profile."""

return self._doProfile()

@endpoints.method(ProfileMiniForm,

ProfileForm,

path='profile',

http_method='POST',

name='saveProfile')

def saveProfile(self, request):

"""Update & return user profile."""

return self._doProfile(request)

# - - - Announcements - - - - - - - - - - - - - - - - - - - -

@staticmethod

def _cacheAnnouncement():

"""Create Announcement & assign to memcache; used by

memcache cron job & putAnnouncement().

"""

confs = Conference.query(ndb.AND(Conference.seatsAvailable <= 5,

Conference.seatsAvailable > 0)).fetch(

projection=[Conference.name])

if confs:

# If there are almost sold out conferences,

# format announcement and set it in memcache

announcement = ANNOUNCEMENT_TPL % (', '.join(conf.name

for conf in confs))

memcache.set(MEMCACHE_ANNOUNCEMENTS_KEY, announcement)

else:

# If there are no sold out conferences,

# delete the memcache announcements entry

announcement = ""

memcache.delete(MEMCACHE_ANNOUNCEMENTS_KEY)

return announcement

@endpoints.method(message_types.VoidMessage,

StringMessage,

path='conference/announcement/get',

http_method='GET',

name='getAnnouncement')

def getAnnouncement(self, request):

"""Return Announcement from memcache."""

return StringMessage(

data=memcache.get(MEMCACHE_ANNOUNCEMENTS_KEY) or "")

# - - - Registration - - - - - - - - - - - - - - - - - - - -

@ndb.transactional(xg=True)

def _conferenceRegistration(self, request, reg=True):

"""Register or unregister user for selected conference."""

retval = None

prof = self._getProfileFromUser() # get user Profile

# check if conf exists given websafeConfKey

# get conference; check that it exists

wsck = request.inputString

conf = ndb.Key(urlsafe=wsck).get()

if not conf:

raise endpoints.NotFoundException(

'No conference found with key: %s' % wsck)

# register

if reg:

# check if user already registered otherwise add

if wsck in prof.conferenceKeysToAttend:

raise ConflictException(

"You have already registered for this conference")

# check if seats avail

if conf.seatsAvailable <= 0:

raise ConflictException("There are no seats available.")

# register user, take away one seat

prof.conferenceKeysToAttend.append(wsck)

conf.seatsAvailable -= 1

retval = True

# unregister

else:

# check if user already registered

if wsck in prof.conferenceKeysToAttend:

# unregister user, add back one seat

prof.conferenceKeysToAttend.remove(wsck)

conf.seatsAvailable += 1

retval = True

else:

retval = False

# write things back to the datastore & return

prof.put()

conf.put()

return BooleanMessage(data=retval)

@endpoints.method(message_types.VoidMessage,

ConferenceForms,

path='conferences/attending',

http_method='GET',

name='getConferencesToAttend')

def getConferencesToAttend(self, request):

"""Get list of conferences that user has registered for."""

prof = self._getProfileFromUser() # get user Profile

conf_keys = [ndb.Key(urlsafe=wsck)

for wsck in prof.conferenceKeysToAttend]

conferences = ndb.get_multi(conf_keys)

# get organizers

organisers = [ndb.Key(Profile, conf.organizerUserId)

for conf in conferences]

profiles = ndb.get_multi(organisers)

# put display names in a dict for easier fetching

names = {}

for profile in profiles:

names[profile.key.id()] = profile.displayName

# return set of ConferenceForm objects per Conference

return ConferenceForms(items=[self._copyConferenceToForm(conf, names[

conf.organizerUserId]) for conf in conferences])

@endpoints.method(GET_OR_DELETE_REQUEST,

BooleanMessage,

path='conference/{inputString}',

http_method='POST',

name='registerForConference')

def registerForConference(self, request):

"""Register user for selected conference."""

return self._conferenceRegistration(request)

@endpoints.method(GET_OR_DELETE_REQUEST,

BooleanMessage,

path='conference/{inputString}',

http_method='DELETE',

name='unregisterFromConference')

def unregisterFromConference(self, request):

"""Unregister user for selected conference."""

return self._conferenceRegistration(request, reg=False)

# ####################################################################### #

# Session methods #

# ####################################################################### #

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #

# Session creation and retrieval #

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #

def _copySessionToForm(self, sess):

sf = SessionForm()

for field in sf.all_fields():

if field.name == "websafeKey":

setattr(sf, field.name, sess.key.urlsafe())

if hasattr(sess, field.name):

if (field.name == "date" or field.name == "time") and getattr(

sess, field.name):

setattr(sf, field.name, str(getattr(sess, field.name)))

elif field.name == 'speakerKey':

# Handle possibility that key is a key or urlsafe key

if type(getattr(sess, field.name)) == ndb.Key:

setattr(sf, field.name, getattr(sess,

field.name).urlsafe())

else:

setattr(sf, field.name, getattr(sess, field.name))

else:

setattr(sf, field.name, getattr(sess, field.name))

sf.check_initialized()

return sf

@endpoints.method(SESS_POST_REQUEST,

SessionForm,

path='sessions',

http_method='POST',

name='createSession')

def createSession(self, request):

"""Create new Session."""

# get the conference

conf = ndb.Key(urlsafe=request.inputString).get()

# check that conference exists

if not conf:

raise endpoints.notfoundexception(

'no conference found with key: %s' % request.inputString)

# user verification

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

if user_id != conf.organizerUserId:

raise endpoints.ForbiddenException(

'Only the owner can update the conference.')

# Verify name

if not request.name:

raise endpoints.BadRequestException(

"Session 'name' field required")

data = {}

for field in request.all_fields():

if field.name == "date" and getattr(request, field.name):

data[field.name] = parse(getattr(request, field.name)).date()

elif field.name == "time" and getattr(request, field.name):

data[field.name] = parse(getattr(request, field.name)).time()

elif field.name == "speakerKey" and getattr(request, field.name):

data[field.name] = ndb.Key(

urlsafe=getattr(request, field.name))

elif field.name == "inputString" or field.name == "websafeKey":

pass

else:

data[field.name] = getattr(request, field.name)

p_key = ndb.Key(urlsafe=request.inputString)

s_id = Session.allocate_ids(size=1, parent=p_key)[0]

s_key = ndb.Key(Session, s_id, parent=p_key)

data['key'] = s_key

key = Session(**data).put().urlsafe()

# Put handling the featured speaker logic on the taskqueue

if data['speakerKey']:

taskqueue.add(params={'speaker': getattr(request, 'speakerKey'),

'conf': conf.key.urlsafe()},

url='/tasks/handle_featured_speaker')

return self._copySessionToForm(ndb.Key(urlsafe=key).get())

@endpoints.method(GET_OR_DELETE_REQUEST,

SessionForms,

path='sessions/{inputString}',

http_method='GET',

name='getConferenceSessions')

def getConferenceSessions(self, request):

"""Given a conference, return all sessions."""

wsck = request.inputString

conf = ndb.Key(urlsafe=wsck).get()

if not conf:

raise endpoints.NotFoundException(

'No conference found with key: %s' % wsck)

sessionObjects = Session.query(ancestor=ndb.Key(urlsafe=wsck))

sessionForms = [self._copySessionToForm(sess)

for sess in sessionObjects]

return SessionForms(items=sessionForms)

@endpoints.method(GET_OR_DELETE_REQUEST,

SessionForms,

path='sessions/speaker/{inputString}',

http_method='GET',

name='getSessionsBySpeaker')

def getSessionsBySpeaker(self, request):

"""Returns all Sessions matching the speaker."""

urlSafeKey = request.inputString

key = ndb.Key(urlsafe=urlSafeKey)

sessionObjects = Session.query(Session.speakerKey == key).fetch()

return SessionForms(

items=[self._copySessionToForm(sess) # TODO: Make sure works empty

for sess in sessionObjects])

# GET_CONF_SESS_BY_TYPE_REQUEST = endpoints.ResourceContainer(

# wsck=message.StringField(1),

# sessType=messages.StringField(2), )

@endpoints.method(GET_CONF_SESS_BY_TYPE_REQUEST,

SessionForms,

path='sessions/type/{wsck}',

http_method='POST',

name='getConferenceSessionsByType')

def getConferenceSessionsByType(self, request):

"""Returns all Sessions matching the session type passed in the address."""

q = Session.query(ancestor=ndb.Key(urlsafe=request.wsck))

sessionObjects = q.filter(Session.typeOfSession == getattr(request,

'sessType'))

if sessionObjects:

return SessionForms(items=[self._copySessionToForm(sess)

for sess in sessionObjects])

raise endpoints.NotFoundException(

'No session found with session type {}'.format(

request.inputString))

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #

# Session wishlist methods #

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #

def _getUserProf(self):

"""Abstracts out common portions of wishlist methods."""

user = endpoints.get_current_user()

if not user:

raise endpoints.UnauthorizedException('Authorization required')

user_id = getUserId(user)

prof = ndb.Key(Profile, user_id).get()

return prof

@endpoints.method(GET_OR_DELETE_REQUEST,

message_types.VoidMessage,

path='wishlist/{inputString}',

http_method='POST',

name='addSessionToWishlist')

def addSessionToWishlist(self, request):

"""Add session to user wishlist."""

prof = self._getUserProf()

sess = ndb.Key(urlsafe=request.inputString).get()

if not sess:

raise endpoints.NotFoundException(

'No session found with key: {}'.format(request.inputString))

# Add to wishlist (or make a new one if empty)

if sess.key in prof.userWishlist: # Handle attempt to add twice.

raise endpoints.BadRequestException(

'Session with key {} already in wishlist.'.format(

request.inputString))

# I am confused because the feedback says that I am "directly assigning

# user input to your database without any error checking" but that I

# "can solve most of them by storing Keys not as Strings, but as Keys

# themselves." But I think I am storing them as keys. They are defined

# in models.py on Profile as

# userWishlist = ndb.KeyProperty(repeated=True)

currentWishlist = getattr(prof, 'userWishlist')

updatedWishlist = currentWishlist.append(

sess.key) if currentWishlist else [sess.key]

setattr(prof, 'userWishlist', updatedWishlist)

print(prof.put().urlsafe()) # for debugging

# prof.put()

return message_types.VoidMessage()

# Assignment interpreted per https://goo.gl/HlVAVK

@endpoints.method(message_types.VoidMessage,

SessionForms,

path='wishlist',

http_method='GET',

name='getSessionsInWishlist')

def getSessionsInWishlist(self, request):

"""Return all wishlisted sessions for signed-in user."""

prof = self._getUserProf()

wishlistKeys = getattr(prof, 'userWishlist')

sessionForms = [self._copySessionToForm(key.get())

for key in wishlistKeys]

return SessionForms(items=sessionForms)

@endpoints.method(GET_OR_DELETE_REQUEST,

message_types.VoidMessage,

path='wishlist/{inputString}',

http_method='DELETE',

name='deleteSessionInWishlist')

def deleteSessionInWishlist(self, request):

"""Delete a session from wishlist."""

prof = self._getUserProf()

sess = ndb.Key(urlsafe=request.inputString).get()

if not sess:

raise endpoints.NotFoundException(

'No session found with key: {}'.format(request.inputString))

currentWishlist = getattr(prof, 'userWishlist')

try:

updatedWishlist = currentWishlist.remove(sess.key)

if not updatedWishlist:

setattr(prof, 'userWishlist', [])

else:

setattr(prof, 'userWishlist', updatedWishlist)

print(prof.put().urlsafe()) # for debugging

# prof.put() # for production

except ValueError:

raise endpoints.NotFoundException(

'Session with key {} not in wishlist.'.format(

request.inputString))

return message_types.VoidMessage()

# ####################################################################### #

# Speaker methods #

# ####################################################################### #

@endpoints.method(SpeakerForm,

SpeakerForm,

path='speaker',

http_method='POST',

name='createSpeaker')

def createSpeaker(self, request):

"""Create a speaker."""

if not request.name:

raise endpoints.BadRequestException(

"Speaker 'name' field required")

speaker = Speaker(name=request.name)

key = speaker.put().urlsafe() # for debugging

print(key) # for debugging

return SpeakerForm(name=request.name, websafeKey=key)

@endpoints.method(GET_OR_DELETE_REQUEST,

SpeakerForm,

path='speaker/{inputString}',

http_method='GET',

name='getSpeaker')

def getSpeaker(self, request):

"""Given a websafe key, returns the appropriate speaker."""

speaker = ndb.Key(urlsafe=request.inputString).get()

if not speaker:

raise endpoints.NotFoundException(

'No conference found with key: %s' % request.inputString)

return SpeakerForm(name=getattr(speaker, 'name'))

@endpoints.method(message_types.VoidMessage,

StringMessage,

path='featured',

http_method='GET',

name='getFeaturedSpeaker')

def getFeaturedSpeaker(self, request):

"""Returns the name of the featured speaker if set else empty

string."""

featured = memcache.get(MEMCACHE_FEATURED_KEY) or ""

return StringMessage(data=featured)

# ####################################################################### #

# Queries #

# ####################################################################### #

@endpoints.method(message_types.VoidMessage,

SessionForms,

path='query/noworkshopsorlatenights',

http_method='GET',

name='query_noWorkshopsOrLateNights')

def query_noWorkshopsOrLateNights(self, request):

"""How would you handle a query for all non-workshop sessions before 7

pm?"""

# As suggested here: http://goo.gl/HtsZT2

q1 = Session.query(Session.typeOfSession != 'Workshop').fetch(

keys_only=True)

q2 = Session.query(Session.time < time(19)).fetch(keys_only=True)

sessionObjects = ndb.get_multi(set(q1).intersection(q2))

sessionForms = [self._copySessionToForm(sess)

for sess in sessionObjects]

return SessionForms(items=sessionForms)

@endpoints.method(message_types.VoidMessage,

SessionForms,

path='query/afterlunchsessions',

http_method='GET',

name='query_afterLunchSessions')

def query_afterLunchSessions(self, request):

"""Select only sessions starting after 1 p.m."""

sessionObjects = Session.query(Session.time >= time(13)).fetch()

sessionForms = [self._copySessionToForm(sess)

for sess in sessionObjects]

return SessionForms(items=sessionForms)

@endpoints.method(message_types.VoidMessage,

ConferenceForms,

path='query/smallconferences',

http_method='GET',

name='query_smallConferences')

def query_smallConferences(self, request):

"""Select only conferences with fewer than 50 maxAttendees."""

conferenceObjects = Conference.query(Conference.maxAttendees < 50)

conferenceForms = []

if conferenceObjects:

for conf in conferenceObjects:

displayName = None

if hasattr(conf.key.parent().get(), 'displayName'):

displayName = getattr(conf.key.parent().get(),

'displayName')

form = self._copyConferenceToForm(conf, displayName)

conferenceForms.append(form)