jsons.deserializers.default_set_deserializer() - Code Metrics - Inspection of "changed md to rst." - ramonhagenaars/jsons - Measure and Improve Code Quality continuously with Scrutinizer

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Branch — master (272386)

by Ramon

created 2018-08-20 06:00 UTC

jsons.deserializers.default_set_deserializer() A

↳ Parent: jsons.deserializers

Complexity

Conditions

Size

Total Lines	14
Code Lines	6

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	2
eloc	6
nop	3
dl	0
loc	14
rs	10
c	0
b	0
f	0

"""
This module contains default deserializers. You can override the
deserialization process of a particular type as follows:

``jsons.set_deserializer(custom_deserializer, SomeClass)``
"""
import inspect
import re
from datetime import datetime, timezone, timedelta
from enum import EnumMeta
from typing import List, Callable
from jsons import _common_impl
from jsons._common_impl import RFC3339_DATETIME_PATTERN, snakecase, \
    camelcase, pascalcase, lispcase


def default_datetime_deserializer(obj: str, _: datetime, **__) -> datetime:
    """
    Deserialize a string with an RFC3339 pattern to a datetime instance.
    :param obj:
    :param _: not used.
    :param __: not used.
    :return: a ``datetime.datetime`` instance.
    """
    pattern = RFC3339_DATETIME_PATTERN
    if '.' in obj:
        pattern += '.%f'
        # strptime allows a fraction of length 6, so trip the rest (if exists).
        regex_pattern = re.compile(r'(\.[0-9]+)')
        frac = regex_pattern.search(obj).group()
        obj = obj.replace(frac, frac[0:7])
    if obj[-1] == 'Z':
        dattim_str = obj[0:-1]
        dattim_obj = datetime.strptime(dattim_str, pattern)
        dattim_obj = datetime(dattim_obj.year, dattim_obj.month,
                              dattim_obj.day, dattim_obj.hour,
                              dattim_obj.minute, dattim_obj.second,
                              dattim_obj.microsecond, timezone.utc)
    else:
        dattim_str, offset = obj.split('+')
        dattim_obj = datetime.strptime(dattim_str, pattern)
        hours, minutes = offset.split(':')
        tz = timezone(offset=timedelta(hours=int(hours), minutes=int(minutes)))

        datetime_list = [dattim_obj.year, dattim_obj.month, dattim_obj.day,
                         dattim_obj.hour, dattim_obj.minute, dattim_obj.second,
                         dattim_obj.microsecond, tz]
        dattim_obj = datetime(*datetime_list)
    return dattim_obj


def default_list_deserializer(obj: List, cls, **kwargs) -> object:
    """
    Deserialize a list by deserializing all items of that list.
    :param obj: the list that needs deserializing.
    :param cls: the type optionally with a generic (e.g. List[str]).
    :param kwargs: any keyword arguments.
    :return: a deserialized list instance.
    """
    cls_ = None
    if cls and hasattr(cls, '__args__'):
        cls_ = cls.__args__[0]
    return [_common_impl.load(x, cls_, **kwargs) for x in obj]


def default_tuple_deserializer(obj: List, cls, **kwargs) -> object:
    """
    Deserialize a (JSON) list into a tuple by deserializing all items of that
    list.
    :param obj: the list that needs deserializing.
    :param cls: the type optionally with a generic (e.g. Tuple[str, int]).
    :param kwargs: any keyword arguments.
    :return: a deserialized tuple instance.
    """
    if hasattr(cls, '__tuple_params__'):
        tuple_types = cls.__tuple_params__
    else:
        tuple_types = cls.__args__
    list_ = [_common_impl.load(obj[i], tuple_types[i], **kwargs)
             for i in range(len(obj))]
    return tuple(list_)


def default_set_deserializer(obj: List, cls, **kwargs) -> object:
    """
    Deserialize a (JSON) list into a set by deserializing all items of that
    list.
    :param obj: the list that needs deserializing.
    :param cls: the type optionally with a generic (e.g. Set[str]).
    :param kwargs: any keyword arguments.
    :return: a deserialized set instance.
    """
    cls_ = list
    if hasattr(cls, '__args__'):
        cls_ = List[cls.__args__[0]]
    list_ = default_list_deserializer(obj, cls_, **kwargs)
    return set(list_)


def default_dict_deserializer(obj: dict, _: type,
                              key_transformer: Callable[[str], str] = None,
                              **kwargs) -> object:
    """
    Deserialize a dict by deserializing all instances of that dict.
    :param obj: the dict that needs deserializing.
    :param key_transformer: a function that transforms the keys to a different
    style (e.g. PascalCase).
    :param cls: not used.
    :param kwargs: any keyword arguments.
    :return: a deserialized dict instance.
    """
    key_transformer = key_transformer or (lambda key: key)
    kwargs_ = {**{'key_transformer': key_transformer}, **kwargs}
    return {key_transformer(key): _common_impl.load(obj[key], **kwargs_)
            for key in obj}


def default_enum_deserializer(obj: str, cls: EnumMeta,
                              use_enum_name: bool = True, **__) -> object:
    """
    Deserialize an enum value to an enum instance. The serialized value must
    can be the name of the enum element or the value; dependent on
    ``use_enum_name``.
    :param obj: the serialized enum.
    :param cls: the enum class.
    :param use_enum_name: determines whether the name or the value of an enum
    element should be used.
    :param __: not used.
    :return: the corresponding enum element instance.
    """
    if use_enum_name:
        result = cls[obj]
    else:
        for elem in cls:
            if elem.value == obj:
                result = elem
                break
    return result



def default_string_deserializer(obj: str, _: type = None, **kwargs) -> object:
    """
    Deserialize a string. If the given ``obj`` can be parsed to a date, a
    ``datetime`` instance is returned.
    :param obj: the string that is to be deserialized.
    :param _: not used.
    :param kwargs: any keyword arguments.
    :return: the deserialized obj.
    """
    try:
        # Use load instead of default_datetime_deserializer to allow the
        # datetime deserializer to be overridden.
        return _common_impl.load(obj, datetime, **kwargs)
    except:

        return obj


def default_primitive_deserializer(obj: object,
                                   _: type = None, **__) -> object:
    """
    Deserialize a primitive: it simply returns the given primitive.
    :param obj: the value that is to be deserialized.
    :param _: not used.
    :param __: not used.
    :return: ``obj``.
    """
    return obj


def default_object_deserializer(obj: dict, cls: type,
                                key_transformer: Callable[[str], str] = None,
                                **kwargs) -> object:
    """
    Deserialize ``obj`` into an instance of type ``cls``. If ``obj`` contains
    keys with a certain case style (e.g. camelCase) that do not match the style
    of ``cls`` (e.g. snake_case), a key_transformer should be used (e.g.
    KEY_TRANSFORMER_SNAKECASE).
    :param obj: a serialized instance of ``cls``.
    :param cls: the type to which ``obj`` should be deserialized.
    :param key_transformer: a function that transforms the keys in order to
    match the attribute names of ``cls``.
    :param kwargs: any keyword arguments that may be passed to the
    deserializers.
    :return: an instance of type ``cls``.
    """
    concat_kwargs = kwargs
    if key_transformer:
        obj = {key_transformer(key): obj[key] for key in obj}
        concat_kwargs = {**kwargs, 'key_transformer': key_transformer}
    signature_parameters = inspect.signature(cls.__init__).parameters
    constructor_args = _get_constructor_args(obj, signature_parameters,
                                             **concat_kwargs)
    remaining_attrs = {attr_name: obj[attr_name] for attr_name in obj
                       if attr_name not in constructor_args}
    instance = cls(**constructor_args)
    _set_remaining_attrs(instance, remaining_attrs, **kwargs)
    return instance


def _get_constructor_args(obj, signature_parameters, **kwargs):
    # Loop through the signature of cls: the type we try to deserialize to. For
    # every required parameter, we try to get the corresponding value from
    # json_obj.
    constructor_args = dict()
    sigs = [(sig_key, sig) for sig_key, sig in signature_parameters.items()
            if obj and sig_key != 'self' and sig_key in obj]
    for sig_key, sig in sigs:
        cls = sig.annotation if sig.annotation != inspect._empty else None
        value = _common_impl.load(obj[sig_key], cls, **kwargs)
        constructor_args[sig_key] = value
    return constructor_args


def _set_remaining_attrs(instance, remaining_attrs, **kwargs):
    # Set any remaining attributes on the newly created instance.
    for attr_name in remaining_attrs:
        loaded_attr = _common_impl.load(remaining_attrs[attr_name],
                                             type(remaining_attrs[attr_name]),

                                             **kwargs)

        try:
            setattr(instance, attr_name, loaded_attr)
        except AttributeError:
            pass  # This is raised when a @property does not have a setter.


# The following default key transformers can be used with the
# default_object_serializer.
KEY_TRANSFORMER_SNAKECASE = snakecase
KEY_TRANSFORMER_CAMELCASE = camelcase
KEY_TRANSFORMER_PASCALCASE = pascalcase
KEY_TRANSFORMER_LISPCASE = lispcase


1			"""
2			This module contains default deserializers. You can override the
3			deserialization process of a particular type as follows:
4
5			``jsons.set_deserializer(custom_deserializer, SomeClass)``
6			"""
7			import inspect
8			import re
9			from datetime import datetime, timezone, timedelta
10			from enum import EnumMeta
11			from typing import List, Callable
12			from jsons import _common_impl
13			from jsons._common_impl import RFC3339_DATETIME_PATTERN, snakecase, \
14			camelcase, pascalcase, lispcase
15
16
17			def default_datetime_deserializer(obj: str, _: datetime, **__) -> datetime:
18			"""
19			Deserialize a string with an RFC3339 pattern to a datetime instance.
20			:param obj:
21			:param _: not used.
22			:param __: not used.
23			:return: a ``datetime.datetime`` instance.
24			"""
25			pattern = RFC3339_DATETIME_PATTERN
26			if '.' in obj:
27			pattern += '.%f'
28			# strptime allows a fraction of length 6, so trip the rest (if exists).
29			regex_pattern = re.compile(r'(\.[0-9]+)')
30			frac = regex_pattern.search(obj).group()
31			obj = obj.replace(frac, frac[0:7])
32			if obj[-1] == 'Z':
33			dattim_str = obj[0:-1]
34			dattim_obj = datetime.strptime(dattim_str, pattern)
35			dattim_obj = datetime(dattim_obj.year, dattim_obj.month,
36			dattim_obj.day, dattim_obj.hour,
37			dattim_obj.minute, dattim_obj.second,
38			dattim_obj.microsecond, timezone.utc)
39			else:
40			dattim_str, offset = obj.split('+')
41			dattim_obj = datetime.strptime(dattim_str, pattern)
42			hours, minutes = offset.split(':')
43			tz = timezone(offset=timedelta(hours=int(hours), minutes=int(minutes)))
			0 ignored issues – show Coding Style Naming introduced 2018-07-18 19:18 UTC by Report Bug Copy Issue Report The name `tz` does not conform to the variable naming conventions (`(([a-z][a-z0-9_]{2,30})\|(_[a-z0-9_]*))$`). This check looks for invalid names for a range of different identifiers. You can set regular expressions to which the identifiers must conform if the defaults do not match your requirements. If your project includes a Pylint configuration file, the settings contained in that file take precedence. To find out more about Pylint, please refer to their site. Loading history...
44			datetime_list = [dattim_obj.year, dattim_obj.month, dattim_obj.day,
45			dattim_obj.hour, dattim_obj.minute, dattim_obj.second,
46			dattim_obj.microsecond, tz]
47			dattim_obj = datetime(*datetime_list)
48			return dattim_obj
49
50
51			def default_list_deserializer(obj: List, cls, **kwargs) -> object:
52			"""
53			Deserialize a list by deserializing all items of that list.
54			:param obj: the list that needs deserializing.
55			:param cls: the type optionally with a generic (e.g. List[str]).
56			:param kwargs: any keyword arguments.
57			:return: a deserialized list instance.
58			"""
59			cls_ = None
60			if cls and hasattr(cls, '__args__'):
61			cls_ = cls.__args__[0]
62			return [_common_impl.load(x, cls_, **kwargs) for x in obj]
63
64
65			def default_tuple_deserializer(obj: List, cls, **kwargs) -> object:
66			"""
67			Deserialize a (JSON) list into a tuple by deserializing all items of that
68			list.
69			:param obj: the list that needs deserializing.
70			:param cls: the type optionally with a generic (e.g. Tuple[str, int]).
71			:param kwargs: any keyword arguments.
72			:return: a deserialized tuple instance.
73			"""
74			if hasattr(cls, '__tuple_params__'):
75			tuple_types = cls.__tuple_params__
76			else:
77			tuple_types = cls.__args__
78			list_ = [_common_impl.load(obj[i], tuple_types[i], **kwargs)
79			for i in range(len(obj))]
80			return tuple(list_)
81
82
83			def default_set_deserializer(obj: List, cls, **kwargs) -> object:
84			"""
85			Deserialize a (JSON) list into a set by deserializing all items of that
86			list.
87			:param obj: the list that needs deserializing.
88			:param cls: the type optionally with a generic (e.g. Set[str]).
89			:param kwargs: any keyword arguments.
90			:return: a deserialized set instance.
91			"""
92			cls_ = list
93			if hasattr(cls, '__args__'):
94			cls_ = List[cls.__args__[0]]
95			list_ = default_list_deserializer(obj, cls_, **kwargs)
96			return set(list_)
97
98
99			def default_dict_deserializer(obj: dict, _: type,
100			key_transformer: Callable[[str], str] = None,
101			**kwargs) -> object:
102			"""
103			Deserialize a dict by deserializing all instances of that dict.
104			:param obj: the dict that needs deserializing.
105			:param key_transformer: a function that transforms the keys to a different
106			style (e.g. PascalCase).
107			:param cls: not used.
108			:param kwargs: any keyword arguments.
109			:return: a deserialized dict instance.
110			"""
111			key_transformer = key_transformer or (lambda key: key)
112			kwargs_ = {{'key_transformer': key_transformer}, kwargs}
113			return {key_transformer(key): _common_impl.load(obj[key], **kwargs_)
114			for key in obj}
115
116
117			def default_enum_deserializer(obj: str, cls: EnumMeta,
118			use_enum_name: bool = True, **__) -> object:
119			"""
120			Deserialize an enum value to an enum instance. The serialized value must
121			can be the name of the enum element or the value; dependent on
122			``use_enum_name``.
123			:param obj: the serialized enum.
124			:param cls: the enum class.
125			:param use_enum_name: determines whether the name or the value of an enum
126			element should be used.
127			:param __: not used.
128			:return: the corresponding enum element instance.
129			"""
130			if use_enum_name:
131			result = cls[obj]
132			else:
133			for elem in cls:
134			if elem.value == obj:
135			result = elem
136			break
137			return result
			0 ignored issues – show introduced 2018-07-19 08:52 UTC by Report Bug Copy Issue Report The variable `result` does not seem to be defined for all execution paths. Loading history...
138
139
140			def default_string_deserializer(obj: str, _: type = None, **kwargs) -> object:
141			"""
142			Deserialize a string. If the given ``obj`` can be parsed to a date, a
143			``datetime`` instance is returned.
144			:param obj: the string that is to be deserialized.
145			:param _: not used.
146			:param kwargs: any keyword arguments.
147			:return: the deserialized obj.
148			"""
149			try:
150			# Use load instead of default_datetime_deserializer to allow the
151			# datetime deserializer to be overridden.
152			return _common_impl.load(obj, datetime, **kwargs)
153			except:
			0 ignored issues – show Coding Style Best Practice introduced 2018-07-18 19:18 UTC by Report Bug Copy Issue Report General except handlers without types should be used sparingly. Typically, you would use general except handlers when you intend to specifically handle all types of errors, f.e. when logging. Otherwise, such general error handlers can mask errors in your application that you want to know of. Loading history...
154			return obj
155
156
157			def default_primitive_deserializer(obj: object,
158			_: type = None, **__) -> object:
159			"""
160			Deserialize a primitive: it simply returns the given primitive.
161			:param obj: the value that is to be deserialized.
162			:param _: not used.
163			:param __: not used.
164			:return: ``obj``.
165			"""
166			return obj
167
168
169			def default_object_deserializer(obj: dict, cls: type,
170			key_transformer: Callable[[str], str] = None,
171			**kwargs) -> object:
172			"""
173			Deserialize ``obj`` into an instance of type ``cls``. If ``obj`` contains
174			keys with a certain case style (e.g. camelCase) that do not match the style
175			of ``cls`` (e.g. snake_case), a key_transformer should be used (e.g.
176			KEY_TRANSFORMER_SNAKECASE).
177			:param obj: a serialized instance of ``cls``.
178			:param cls: the type to which ``obj`` should be deserialized.
179			:param key_transformer: a function that transforms the keys in order to
180			match the attribute names of ``cls``.
181			:param kwargs: any keyword arguments that may be passed to the
182			deserializers.
183			:return: an instance of type ``cls``.
184			"""
185			concat_kwargs = kwargs
186			if key_transformer:
187			obj = {key_transformer(key): obj[key] for key in obj}
188			concat_kwargs = {**kwargs, 'key_transformer': key_transformer}
189			signature_parameters = inspect.signature(cls.__init__).parameters
190			constructor_args = _get_constructor_args(obj, signature_parameters,
191			**concat_kwargs)
192			remaining_attrs = {attr_name: obj[attr_name] for attr_name in obj
193			if attr_name not in constructor_args}
194			instance = cls(**constructor_args)
195			_set_remaining_attrs(instance, remaining_attrs, **kwargs)
196			return instance
197
198
199			def _get_constructor_args(obj, signature_parameters, **kwargs):
200			# Loop through the signature of cls: the type we try to deserialize to. For
201			# every required parameter, we try to get the corresponding value from
202			# json_obj.
203			constructor_args = dict()
204			sigs = [(sig_key, sig) for sig_key, sig in signature_parameters.items()
205			if obj and sig_key != 'self' and sig_key in obj]
206			for sig_key, sig in sigs:
207			cls = sig.annotation if sig.annotation != inspect._empty else None
208			value = _common_impl.load(obj[sig_key], cls, **kwargs)
209			constructor_args[sig_key] = value
210			return constructor_args
211
212
213			def _set_remaining_attrs(instance, remaining_attrs, **kwargs):
214			# Set any remaining attributes on the newly created instance.
215			for attr_name in remaining_attrs:
216			loaded_attr = _common_impl.load(remaining_attrs[attr_name],
217			type(remaining_attrs[attr_name]),
			0 ignored issues – show Coding Style introduced 2018-08-19 20:11 UTC by Report Bug Copy Issue Report Wrong continued indentation (remove 5 spaces). Loading history...
218			**kwargs)
			0 ignored issues – show Coding Style introduced 2018-08-19 20:11 UTC by Report Bug Copy Issue Report Wrong continued indentation (remove 5 spaces). Loading history...
219			try:
220			setattr(instance, attr_name, loaded_attr)
221			except AttributeError:
222			pass # This is raised when a @property does not have a setter.
223
224
225			# The following default key transformers can be used with the
226			# default_object_serializer.
227			KEY_TRANSFORMER_SNAKECASE = snakecase
228			KEY_TRANSFORMER_CAMELCASE = camelcase
229			KEY_TRANSFORMER_PASCALCASE = pascalcase
230			KEY_TRANSFORMER_LISPCASE = lispcase
231

ramonhagenaars / jsons

Branch — master (272386)

jsons.deserializers.default_set_deserializer() A

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