def get_dynamodb_type(val, use_boolean=True):
"""
Take a scalar Python value and return a string representing
the corresponding Amazon DynamoDB type. If the value passed in is
not a supported type, raise a TypeError.
"""
dynamodb_type = None
if val is None:
dynamodb_type = 'NULL'
elif is_num(val):
if isinstance(val, bool) and use_boolean:
dynamodb_type = 'BOOL'
else:
dynamodb_type = 'N'
elif is_str(val):
dynamodb_type = 'S'
elif isinstance(val, (set, frozenset)):
if False not in map(is_num, val):
dynamodb_type = 'NS'
elif False not in map(is_str, val):
dynamodb_type = 'SS'
elif False not in map(is_binary, val):
dynamodb_type = 'BS'
elif is_binary(val):
dynamodb_type = 'B'
elif isinstance(val, Mapping):
dynamodb_type = 'M'
elif isinstance(val, list):
dynamodb_type = 'L'
if dynamodb_type is None:
msg = 'Unsupported type "%s" for value "%s"' % (type(val), val)
raise TypeError(msg)
return dynamodb_type
def item_object_hook(dct):
"""
A custom object hook for use when decoding JSON item bodys.
This hook will transform Amazon DynamoDB JSON responses to something
that maps directly to native Python types.
"""
if len(dct.keys()) > 1:
return dct
if 'S' in dct:
return dct['S']
if 'N' in dct:
return convert_num(dct['N'])
if 'SS' in dct:
return set(dct['SS'])
if 'NS' in dct:
return set(map(convert_num, dct['NS']))
if 'B' in dct:
return convert_binary(dct['B'])
if 'BS' in dct:
return set(map(convert_binary, dct['BS']))
return dct
def dynamize_value(val):
"""
Take a scalar Python value and return a dict consisting
of the Amazon DynamoDB type specification and the value that
needs to be sent to Amazon DynamoDB. If the type of the value
is not supported, raise a TypeError
"""
dynamodb_type = get_dynamodb_type(val)
if dynamodb_type == 'N':
val = {dynamodb_type: serialize_num(val)}
elif dynamodb_type == 'S':
val = {dynamodb_type: val}
elif dynamodb_type == 'NS':
val = {dynamodb_type: list(map(serialize_num, val))}
elif dynamodb_type == 'SS':
val = {dynamodb_type: [n for n in val]}
elif dynamodb_type == 'B':
if isinstance(val, bytes):
val = Binary(val)
val = {dynamodb_type: val.encode()}
elif dynamodb_type == 'BS':
val = {dynamodb_type: [n.encode() for n in val]}
return val
def _decode_ns(self, attr):
return set(map(self._decode_n, attr))
def _decode_bs(self, attr):
return set(map(self._decode_b, attr))
def _decode_ss(self, attr):
return set(map(self._decode_s, attr))
def _encode_ns(self, attr):
return list(map(self._encode_n, attr))
