2.5. fancytypes.PreSerializable

class PreSerializable(skip_validation_and_conversion=False, skip_cls_tests=False, **kwargs)

Bases: Checkable

A type that is pre-serializable, that can be constructed from a serializable representation, and that can perform user-defined validations and conversions of a set of parameters upon construction.

We define pre-serialization as the process of converting an object into a form that can be subsequently serialized into a JSON format. We refer to objects resulting from pre-serialization as serializable objects.

We define de-pre-serialization as the process of converting a serializable object into an instance of the current class, i.e. de-pre-serialization is the reverse process of pre-serialization.

One cannot construct an instance of the class fancytypes.PreSerializable without raising an exception. In order to make use of this class, one must create a subclass that inherits from fancytypes.PreSerializable and then override the class methods get_validation_and_conversion_funcs, pre_serialization_funcs, and de_pre_serialization_funcs in ways that are consistent with the respective descriptions of the methods.

Parameters:

• skip_validation_and_conversion (bool, optional) –

  Let validation_and_conversion_funcs and core_attrs denote the attributes validation_and_conversion_funcs and core_attrs respectively, both of which being dict objects.

  Let params_to_be_mapped_to_core_attrs denote the dict representation of the constructor parameters excluding the parameters skip_validation_and_conversion and skip_cls_tests, where each dict key key is a different constructor parameter name, excluding the names "skip_validation_and_conversion" and "skip_cls_tests", and params_to_be_mapped_to_core_attrs[key] would yield the value of the constructor parameter with the name given by key.

  If skip_validation_and_conversion is set to False, then for each key key in params_to_be_mapped_to_core_attrs, core_attrs[key] is set to validation_and_conversion_funcs[key] (params_to_be_mapped_to_core_attrs).

  Otherwise, if skip_validation_and_conversion is set to True, then core_attrs is set to params_to_be_mapped_to_core_attrs.copy(). This option is desired primarily when the user wants to avoid potentially expensive deep copies and/or conversions of the dict values of params_to_be_mapped_to_core_attrs, as it is guaranteed that no copies or conversions are made in this case.

• skip_cls_test (bool, optional) –

  If skip_cls_test is set to False, then upon construction, tests will be performed to check whether the class was properly defined. If any of the tests fail, an exception will be raised.

  Otherwise, if skip_cls_test is set to True, these tests will be skipped.

  One should only skip the tests if they are sure that the class is properly defined. Skipping the tests will yield some improvement in performance.

• **kwargs – The remaining constructor parameters.

Methods

de_pre_serialize	Construct an instance from a serializable representation.
dump	Serialize instance and save the result in a JSON file.
dumps	Serialize instance.
get_core_attrs	Return the core attributes.
get_de_pre_serialization_funcs	Return the de-pre-serialization functions.
get_pre_serialization_funcs	Return the pre-serialization functions.
get_validation_and_conversion_funcs	Return the validation and conversion functions.
load	Construct an instance from a serialized representation that is stored in a JSON file.
loads	Construct an instance from a serialized representation.
pre_serialize	Pre-serialize instance.

Attributes

core_attrs	The "core attributes".
de_pre_serialization_funcs	The de-pre-serialization functions.
pre_serialization_funcs	The pre-serialization functions.
validation_and_conversion_funcs	The validation and conversion functions.

property core_attrs

The “core attributes”.

The keys of core_attrs are the same as the attribute validation_and_conversion_funcs, which is also a dict object.

Note that core_attrs should be considered read-only.

Type:

dict

property de_pre_serialization_funcs

The de-pre-serialization functions.

de_pre_serialization_funcs has the same keys as the attribute validation_and_conversion_funcs, which is also a dict object.

Let validation_and_conversion_funcs and pre_serialization_funcs denote the attributes validation_and_conversion_funcs pre_serialization_funcs respectively, the last of which being a dict object as well.

Let core_attrs_candidate_1 be any dict object that has the same keys as validation_and_conversion_funcs, where for each dict key key in core_attrs_candidate_1, validation_and_conversion_funcs[key](core_attrs_candidate_1) does not raise an exception.

Let serializable_rep be a dict object that has the same keys as core_attrs_candidate_1, where for each dict key key in core_attrs_candidate_1, serializable_rep[key] is set to pre_serialization_funcs[key](core_attrs_candidate_1[key]).

The items of de_pre_serialization_funcs are expected to be set to callable objects that would lead to de_pre_serialization_funcs[key](serializable_rep[key]) not raising an exception for each dict key key in serializable_rep.

Let core_attrs_candidate_2 be a dict object that has the same keys as serializable_rep, where for each dict key key in validation_and_conversion_funcs, core_attrs_candidate_2[key] is set to de_pre_serialization_funcs[key](serializable_rep[key]).

The items of de_pre_serialization_funcs are also expected to be set to callable objects that would lead to validation_and_conversion_funcs[key](core_attrs_candidate_2) not raising an exception for each dict key key in core_attrs_candidate_2.

Note that de_pre_serialization_funcs should be considered read-only.

Type:

dict

classmethod de_pre_serialize(serializable_rep={}, skip_validation_and_conversion=False)

Construct an instance from a serializable representation.

Parameters:

• serializable_rep (dict, optional) –

  A dict object that has the same keys as the attribute validation_and_conversion_funcs, which is also a dict object.

  Let validation_and_conversion_funcs and de_pre_serialization_funcs denote the attributes validation_and_conversion_funcs de_pre_serialization_funcs respectively, the last of which being a dict object as well.

  The items of serializable_rep are expected to be objects that would lead to de_pre_serialization_funcs[key](serializable_rep[key]) not raising an exception for each dict key key in serializable_rep.

  Let core_attrs_candidate be a dict object that has the same keys as serializable_rep, where for each dict key key in serializable_rep, core_attrs_candidate[key] is set to de_pre_serialization_funcs[key](serializable_rep[key])``.

  The items of serializable_rep are also expected to be set to objects that would lead to validation_and_conversion_funcs[key](core_attrs_candidate) not raising an exception for each dict key key in serializable_rep.

• skip_validation_and_conversion (bool, optional) –

  Let core_attrs denote the attribute core_attrs, which is a dict object.

  If skip_validation_and_conversion is set to False, then for each key key in serializable_rep, core_attrs[key] is set to validation_and_conversion_funcs[key] (core_attrs_candidate), with validation_and_conversion_funcs and core_attrs_candidate_1 being introduced in the above description of serializable_rep.

  Otherwise, if skip_validation_and_conversion is set to True, then core_attrs is set to core_attrs_candidate.copy(). This option is desired primarily when the user wants to avoid potentially expensive deep copies and/or conversions of the dict values of core_attrs_candidate, as it is guaranteed that no copies or conversions are made in this case.

Returns:

instance_of_current_cls – An instance constructed from the serializable representation serializable_rep.

Return type:

Current class

dump(filename='serialized_rep_of_fancytype.json', overwrite=False)

Serialize instance and save the result in a JSON file.

Parameters:

• filename (str, optional) – The relative or absolute path to the JSON file in which to store the serialized representation of an instance.

• overwrite (bool, optional) – If overwrite is set to False and a file exists at the path filename, then the serialized instance is not written to that file and an exception is raised. Otherwise, the serialized instance will be written to that file barring no other issues occur.

dumps()

Serialize instance.

Returns:

serialized_rep – A serialized representation of an instance.

Return type:

dict

get_core_attrs(deep_copy=True)

Return the core attributes.

Parameters:

deep_copy (bool, optional) –

Let core_attrs denote the attribute core_attrs, which is a dict object.

If deep_copy is set to True, then a deep copy of core_attrs is returned. Otherwise, a shallow copy of core_attrs is returned.

Returns:

core_attrs – The attribute core_attrs.

Return type:

dict

classmethod get_de_pre_serialization_funcs()

Return the de-pre-serialization functions.

Returns:

de_pre_serialization_funcs – The attribute de_pre_serialization_funcs.

Return type:

dict

classmethod get_pre_serialization_funcs()

Return the pre-serialization functions.

Returns:

pre_serialization_funcs – The attribute pre_serialization_funcs.

Return type:

dict

classmethod get_validation_and_conversion_funcs()

Return the validation and conversion functions.

Returns:

validation_and_conversion_funcs – The attribute validation_and_conversion_funcs.

Return type:

dict

classmethod load(filename='serialized_rep_of_fancytype.json', skip_validation_and_conversion=False)

Construct an instance from a serialized representation that is stored in a JSON file.

Users can save serialized representations to JSON files using the method fancytypes.PreSerializable.dump().

Parameters:

• filename (str, optional) –

  The relative or absolute path to the JSON file that is storing the serialized representation of an instance.

  filename is expected to be such that json.load(open(filename, "r")) does not raise an exception.

  Let serializable_rep=json.load(open(filename, "r")).

  Let validation_and_conversion_funcs and de_pre_serialization_funcs denote the attributes validation_and_conversion_funcs de_pre_serialization_funcs respectively, both of which being dict objects as well.

  filename is also expected to be such that de_pre_serialization_funcs[key](serializable_rep[key]) does not raise an exception for each dict key key in de_pre_serialization_funcs.

  Let core_attrs_candidate be a dict object that has the same keys as de_pre_serialization_funcs, where for each dict key key in serializable_rep, core_attrs_candidate[key] is set to de_pre_serialization_funcs[key](serializable_rep[key])``.

  filename is also expected to be such that validation_and_conversion_funcs[key](core_attrs_candidate) does not raise an exception for each dict key key in serializable_rep.

• skip_validation_and_conversion (bool, optional) –

  Let core_attrs denote the attribute core_attrs, which is a dict object.

  Let core_attrs_candidate be as defined in the above description of filename.

  If skip_validation_and_conversion is set to False, then for each key key in core_attrs_candidate, core_attrs[key] is set to validation_and_conversion_funcs[key] (core_attrs_candidate), , with validation_and_conversion_funcs and core_attrs_candidate being introduced in the above description of filename.

  Otherwise, if skip_validation_and_conversion is set to True, then core_attrs is set to core_attrs_candidate.copy(). This option is desired primarily when the user wants to avoid potentially expensive deep copies and/or conversions of the dict values of core_attrs_candidate, as it is guaranteed that no copies or conversions are made in this case.

Returns:

instance_of_current_cls – An instance constructed from the serialized representation stored in the JSON file.

Return type:

Current class

classmethod loads(serialized_rep='{}', skip_validation_and_conversion=False)

Construct an instance from a serialized representation.

Users can generate serialized representations using the method dumps().

Parameters:

• serialized_rep (str | bytes | bytearray, optional) –

  The serialized representation.

  serialized_rep is expected to be such that json.loads(serialized_rep) does not raise an exception.

  Let serializable_rep=json.loads(serialized_rep).

  Let validation_and_conversion_funcs and de_pre_serialization_funcs denote the attributes validation_and_conversion_funcs de_pre_serialization_funcs respectively, both of which being dict objects as well.

  serialized_rep is also expected to be such that de_pre_serialization_funcs[key](serializable_rep[key]) does not raise an exception for each dict key key in de_pre_serialization_funcs.

  Let core_attrs_candidate be a dict object that has the same keys as serializable_rep, where for each dict key key in de_pre_serialization_funcs, core_attrs_candidate[key] is set to de_pre_serialization_funcs[key](serializable_rep[key])``.

  serialized_rep is also expected to be such that validation_and_conversion_funcs[key](core_attrs_candidate) does not raise an exception for each dict key key in serializable_rep.

• skip_validation_and_conversion (bool, optional) –

  Let core_attrs denote the attribute core_attrs, which is a dict object.

  If skip_validation_and_conversion is set to False, then for each key key in core_attrs_candidate, core_attrs[key] is set to validation_and_conversion_funcs[key] (core_attrs_candidate), with validation_and_conversion_funcs and core_attrs_candidate_1 being introduced in the above description of serialized_rep.

  Otherwise, if skip_validation_and_conversion is set to True, then core_attrs is set to core_attrs_candidate.copy(). This option is desired primarily when the user wants to avoid potentially expensive deep copies and/or conversions of the dict values of core_attrs_candidate, as it is guaranteed that no copies or conversions are made in this case.

Returns:

instance_of_current_cls – An instance constructed from the serialized representation.

Return type:

Current class

property pre_serialization_funcs

The pre-serialization functions.

pre_serialization_funcs has the same keys as the attribute validation_and_conversion_funcs, which is also a dict object.

Let validation_and_conversion_funcs and core_attrs denote the attributes validation_and_conversion_funcs and core_attrs respectively, the last of which being a dict object as well.

For each dict key key in core_attrs, pre_serialization_funcs[key](core_attrs[key]) is expected to yield a serializable object, i.e. it should yield an object that can be passed into the function json.dumps without raising an exception.

Note that pre_serialization_funcs should be considered read-only.

Type:

dict

pre_serialize()

Pre-serialize instance.

Returns:

serializable_rep – A serializable representation of an instance.

Return type:

dict

property validation_and_conversion_funcs

The validation and conversion functions.

The keys of validation_and_conversion_funcs are the names of the constructor parameters, excluding skip_validation_and_conversion if it exists as a construction parameter.

Let core_attrs denote the attribute core_attrs, which is also a dict object.

For each dict key key in core_attrs, validation_and_conversion_funcs[key](core_attrs) is expected to not raise an exception.

Note that validation_and_conversion_funcs should be considered read-only.

Type:

dict