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import json
TYPES = {}
NOTYPES = {}
class CustomTypeEncoder(json.JSONEncoder):
"""A custom JSONEncoder class that knows how to encode core custom
objects.
Custom objects are encoded as JSON object literals (ie, dicts) with
one key, 'TypeName' where 'TypeName' is the actual name of the
type to which the object belongs. That single key maps to another
object literal which is just the __dict__ of the object encoded.
Reason for ignoring the error
E0202 - An attribute affected in json.encoder line 157 hide this method
reported by pylint:
The error is in json.encoder.JSONEncoder class.
There is a default method (which is overridden here) and also a class
attribute self.default initialized in the init method of the class.
The intention of such usage being that a custom default method object can
be passed to init when creating an instance of JSONEncoder, which is then
assigned to class's default method. (which is valid)
But pylint raises an issue due to the usage of same name for a method and
an attribute in which case the attribute definition hides the method.
The reason and example for the issue: (top rated comment)
http://stackoverflow.com/questions/12949064/python-what-happens-
when-instance-variable-name-is-same-as-method-name
"""
# pylint: disable-msg=E0202
def default(self, obj):
for k, v in TYPES.items():
if isinstance(obj, v):
return {k: obj.__dict__}
for k, v in NOTYPES.items():
if isinstance(obj, v):
return self.attr_name_conversion(obj.__dict__, v)
return json.JSONEncoder.default(self, obj)
@staticmethod
def attr_name_conversion(attr_dict, object_class):
if not hasattr(object_class, 'json_attribute_names'):
return attr_dict
for k, v in object_class.json_attribute_names.items():
if v in attr_dict:
value = attr_dict[v]
del attr_dict[v]
attr_dict[k] = value
return attr_dict
def CustomTypeDecoder(dct):
if len(dct) == 1:
type_name, value = dct.items()[0]
if type_name in TYPES:
return TYPES[type_name].from_dict(value)
return dct
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