def from_json(record_type, json_struct):
"""JSON marshall in function: a 'visitor' function which looks for JSON
types/hints on types being converted to, but does not require them.
Args:
``record_type=``\ *TYPE*
Record type to convert data to
``json_struct=``\ *DICT|LIST*
a loaded (via ``json.loads``) data structure, normally a
dict or a list.
"""
if issubclass(record_type, JsonRecord):
return record_type(json_struct)
elif issubclass(record_type, Record):
# do what the default JsonRecord __init__ does
init_kwargs = json_to_initkwargs(record_type, json_struct)
instance = record_type(**init_kwargs)
return instance
else:
raise exc.JsonRecordCoerceError(
given=repr(json_struct),
type=record_type.__name__,
)
def json_to_initkwargs(record_type, json_struct, kwargs=None):
"""This function converts a JSON dict (json_struct) to a set of init
keyword arguments for the passed Record (or JsonRecord).
It is called by the JsonRecord constructor. This function takes a JSON
data structure and returns a keyword argument list to be passed to the
class constructor. Any keys in the input dictionary which are not known
are passed as a single ``unknown_json_keys`` value as a dict.
This function should generally not be called directly, except as a part of
a ``__init__`` or specialized visitor application.
"""
if kwargs is None:
kwargs = {}
if json_struct is None:
json_struct = {}
if not isinstance(json_struct, dict):
raise exc.JsonRecordCoerceError(
passed=json_struct,
recordtype=record_type,
)
unknown_keys = set(json_struct.keys())
for propname, prop in record_type.properties.items():
# think "does" here rather than "is"; the slot does JSON
if isinstance(prop, JsonProperty):
json_name = prop.json_name
if json_name is not None:
if json_name in json_struct:
if propname not in kwargs:
try:
kwargs[propname] = _json_to_value_initializer(
prop.from_json(
json_struct[json_name]
),
prop.valuetype,
)
except Exception as e:
raise _box_ingress_error(json_name, e)
unknown_keys.remove(json_name)
elif prop.name in json_struct:
json_val = json_struct[prop.name]
unknown_keys.remove(prop.name)
if prop.name not in kwargs:
proptype = prop.valuetype
try:
kwargs[propname] = _json_to_value_initializer(
json_val, proptype,
)
except Exception as e:
raise _box_ingress_error(prop.name, e)
if unknown_keys:
kwargs["unknown_json_keys"] = dict(
(k, deepcopy(json_struct[k])) for k in unknown_keys
)
return kwargs
