def rating_count(user_id=None, user_str=None, place_id=None, place_str=None):
"""
It counts the number of ratings for a user, a place or both.
Parameters:
- user_id and user_str: key (str = urlsafe) for the PFuser, only one needed
- place_id and place_str: key (str = urlsafe) for the Place, only one needed
It returns a tuple:
- the number of ratings,
- the status (a string indicating whether an error occurred)
- the http code indicating the type of error, if any
"""
try:
user_key = PFuser.make_key(user_id, user_str)
place_key = Place.make_key(place_id, place_str)
count = Rating.count(user_key, place_key)
except TypeError as e:
return None, str(e), 400
return count, "OK", 200