v0.27.0: Drop support for Python Versions 3.6, 3.7, and 3.8 (#139)

* bump

* minor fix

* minor fix

* Add test case to satisfy #89

* Support cyclic references (#138)

* support cyclic or self-referential dataclasses

* update to add custom recursion error

* Don't replace RecursionError with RecursiveClassError if recursion-safe loader is already enabled

If we get a `RecursionError` in this case, something else must have gone wrong

---------

Co-authored-by: Ritvik Nag <[email protected]>

* Update all requirements to latest versions

* Update requirements in requirements-dev.txt and requirements-test.txt to latest

* "When you drop py3.6/7/8, remove everything EXCEPT the py.typed file."

* See [comment](#136 (comment))

* Update tests to support Python 3.9+

* Run tests on CI for PY 3.9+
* `typing_extensions` should be required for Python 3.10 (as well as 3.9)

* Starting to purge PY 3.6, 3.7 and 3.8 support

* Fix `Sphinx` dependency issue

* I realized this was a bug!

* Continue with purge of PY 3.6, 3.7, and 3.8

* Continue with purge of PY 3.6, 3.7, and 3.8

* Continue with purge of PY 3.6, 3.7, and 3.8

* This concludes the purge of PY 3.6, 3.7, and 3.8

* Remove unnecessary code

* Remove unnecessary code

* Update docs to mention cyclic or "recursive" dataclasses

* Update docs to remove `typing.List` mentions

* Update docs to remove `typing.List` mentions

* Update HISTORY.rst

---------

Co-authored-by: Dan Lenski <[email protected]>

.github/workflows/dev.yml

@@ -18,7 +18,7 @@ jobs:
     # The type of runner that the job will run on
     strategy:
       matrix:
-        python-versions: [3.6, 3.7, 3.8, 3.9, '3.10', '3.11', '3.12', '3.13']
+        python-versions: [3.9, '3.10', '3.11', '3.12', '3.13']
         os: [ubuntu-20.04]
         # Uncomment if I need to run it on other environments too (currently
         # there's not a huge need)

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
 
     strategy:
       matrix:
-        python-versions: [3.8]
+        python-versions: [3.11]
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:

CONTRIBUTING.rst

@@ -107,7 +107,7 @@ Before you submit a pull request, check that it meets these guidelines:
 2. If the pull request adds functionality, the docs should be updated. Put
    your new functionality into a function with a docstring, and add the
    feature to the list in README.rst.
-3. The pull request should work for Python 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12 and 3.13, and for PyPy. Check
+3. The pull request should work for Python 3.9, 3.10, 3.11, 3.12 and 3.13, and for PyPy. Check
    https://github.com/rnag/dataclass-wizard/actions/workflows/dev.yml
    and make sure that the tests pass for all supported Python versions.
 

HISTORY.rst

@@ -2,6 +2,30 @@
 History
 =======
 
+0.27.0 (2024-11-10)
+-------------------
+
+**Features and Improvements**
+
+* This minor release drops support for Python 3.6, 3.7, and 3.8, all of which have reached End of Life (EOL). Check out the Python End of Life Cycle here_. Key changes resulting from this update include:
+    * Resolved pyup errors, previously flagged as "insecure" due to outdated package versions that lacked support for Python 3.8 or earlier.
+    * Update all requirements to latest versions.
+    * Cleaned up various TODO comments scattered throughout the codebase, as many were specific to older Python versions.
+    * Simplified and improved codebase for easier maintenance.
+    * Remove everything except the ``py.typed`` file (see comment_).
+* Added `test case`_ to satisfy :issue:`89`.
+* Added support for cyclic or "recursive" dataclasses, as first mentioned in :issue:`62` (special thanks to :user:`dlenski` for finalizing this in :pr:`138`!).
+
+**Bugfixes**
+
+* :issue:`62`: Cyclic or "recursive" dataclasses no longer raises a :class:`RecursionError`.
+* Typing locals should now correctly key off the correct Python version, see the commit_ that addressed this.
+
+.. _here: https://devguide.python.org/versions/#status-of-python-versions
+.. _test case: https://github.com/rnag/dataclass-wizard/pull/139/commits/cf2e98cb75c75dc3e566ed0205637dbd4632e159
+.. _comment: https://github.com/rnag/dataclass-wizard/pull/136#issuecomment-2466463153
+.. _commit: https://github.com/rnag/dataclass-wizard/pull/139/commits/310a0c28690fdfdf15a386a427d1ea9aaf8898a1
+
 0.26.1 (2024-11-09)
 -------------------
 

MANIFEST.in

@@ -2,7 +2,6 @@ include CONTRIBUTING.rst
 include HISTORY.rst
 include LICENSE
 include README.rst
-include dataclass_wizard/py.typed
 
 recursive-include tests *.py
 recursive-exclude tests/integration *

Makefile

@@ -36,7 +36,7 @@ clean-build: ## remove build artifacts
 	rm -fr dist/
 	rm -fr .eggs/
 	find . -name '*.egg-info' -exec rm -fr {} +
-	find . -name '*.egg' -exec rm -f {} +
+	find . -name '*.egg' -type f -exec rm -f {} +
 
 clean-pyc: ## remove Python file artifacts
 	find . -name '*.pyc' -exec rm -f {} +

README.rst

@@ -86,7 +86,7 @@ Alternatively, this library is available `on conda`_ under the `conda-forge`_ ch
 
     $ conda install dataclass-wizard -c conda-forge
 
-The ``dataclass-wizard`` library officially supports **Python 3.6** or higher.
+The ``dataclass-wizard`` library officially supports **Python 3.9** or higher.
 
 .. _on conda: https://anaconda.org/conda-forge/dataclass-wizard
 .. _conda-forge: https://conda-forge.org/
@@ -133,7 +133,7 @@ Usage and Examples
 
 Using the built-in JSON marshalling support for dataclasses:
 
-    Note: The following example should work in **Python 3.7+** with the included ``__future__``
+    Note: The following example should work in **Python 3.9+** with the included ``__future__``
     import.
 
 .. code:: python3
@@ -633,9 +633,7 @@ A brief example of the intended usage is shown below:
 
     from dataclasses import dataclass
     from datetime import time, datetime
-    from typing import List
-    # Note: in Python 3.9+, you can import this from `typing` instead
-    from typing_extensions import Annotated
+    from typing import Annotated
 
     from dataclass_wizard import fromdict, asdict, DatePattern, TimePattern, Pattern
 
@@ -645,7 +643,7 @@ A brief example of the intended usage is shown below:
         date_field: DatePattern['%m-%Y']
         dt_field: Annotated[datetime, Pattern('%m/%d/%y %H.%M.%S')]
         time_field1: TimePattern['%H:%M']
-        time_field2: Annotated[List[time], Pattern('%I:%M %p')]
+        time_field2: Annotated[list[time], Pattern('%I:%M %p')]
 
 
     data = {'date_field': '12-2022',
@@ -669,6 +667,61 @@ A brief example of the intended usage is shown below:
     # serialization. In fact, it'll be faster than parsing the custom patterns!
     assert class_obj == fromdict(MyClass, asdict(class_obj))
 
+"Recursive" Dataclasses with Cyclic References
+----------------------------------------------
+
+Prior to version `v0.27.0`, dataclasses with cyclic references
+or self-referential structures were not supported. This
+limitation is shown in the following toy example:
+
+.. code:: python3
+
+    from dataclasses import dataclass
+
+    @dataclass
+    class A:
+        a: 'A | None' = None
+
+    a = A(a=A(a=A(a=A())))
+
+This was a `longstanding issue`_.
+
+New in ``v0.27.0``: The Dataclass Wizard now extends its support
+to cyclic and self-referential dataclass models.
+
+The example below demonstrates recursive dataclasses with cyclic
+dependencies, following the pattern ``A -> B -> A -> B``. For more details, see
+the `Cyclic or "Recursive" Dataclasses`_ section in the documentation.
+
+.. code:: python3
+
+    from __future__ import annotations  # This can be removed in Python 3.10+
+
+    from dataclasses import dataclass
+
+    from dataclass_wizard import JSONWizard
+
+
+    @dataclass
+    class A(JSONWizard):
+        class _(JSONWizard.Meta):
+            # enable support for self-referential / recursive dataclasses
+            recursive_classes = True
+
+        b: 'B | None' = None
+
+
+    @dataclass
+    class B:
+        a: A | None = None
+
+
+    # confirm that `from_dict` with a recursive, self-referential
+    # input `dict` works as expected.
+    a = A.from_dict({'b': {'a': {'b': {'a': None}}}})
+
+    assert a == A(b=B(a=A(b=B())))
+
 Dataclasses in ``Union`` Types
 ------------------------------
 
@@ -778,7 +831,6 @@ result. An example of both these approaches is shown below.
 
     from collections import defaultdict
     from dataclasses import field, dataclass
-    from typing import DefaultDict, List
 
     from dataclass_wizard import JSONWizard
 
@@ -792,8 +844,8 @@ result. An example of both these approaches is shown below.
         my_str: str
         other_str: str = 'any value'
         optional_str: str = None
-        my_list: List[str] = field(default_factory=list)
-        my_dict: DefaultDict[str, List[float]] = field(
+        my_list: list[str] = field(default_factory=list)
+        my_dict: defaultdict[str, list[float]] = field(
             default_factory=lambda: defaultdict(list))
 
 
@@ -925,4 +977,6 @@ This package was created with Cookiecutter_ and the `rnag/cookiecutter-pypackage
 .. _`Patterned Date and Time`: https://dataclass-wizard.readthedocs.io/en/latest/common_use_cases/patterned_date_time.html
 .. _Union: https://docs.python.org/3/library/typing.html#typing.Union
 .. _`Dataclasses in Union Types`: https://dataclass-wizard.readthedocs.io/en/latest/common_use_cases/dataclasses_in_union_types.html
+.. _`Cyclic or "Recursive" Dataclasses`: https://dataclass-wizard.readthedocs.io/en/latest/common_use_cases/cyclic_or_recursive_dataclasses.html
 .. _as milestones: https://github.com/rnag/dataclass-wizard/milestones
+.. _longstanding issue: https://github.com/rnag/dataclass-wizard/issues/62

dataclass_wizard/__init__.py

@@ -9,7 +9,7 @@
 
     >>> from dataclasses import dataclass, field
     >>> from datetime import datetime
-    >>> from typing import Optional, List
+    >>> from typing import Optional
     >>>
     >>> from dataclass_wizard import JSONSerializable, property_wizard
     >>>
@@ -18,7 +18,7 @@
     >>> class MyClass(JSONSerializable, metaclass=property_wizard):
     >>>
     >>>     my_str: Optional[str]
-    >>>     list_of_int: List[int] = field(default_factory=list)
+    >>>     list_of_int: list[int] = field(default_factory=list)
     >>>     # You can also define this as `my_dt`, however only the annotation
     >>>     # will carry over in that case, since the value is re-declared by
     >>>     # the property below.
@@ -98,7 +98,6 @@
 import logging
 
 from .bases_meta import LoadMeta, DumpMeta
-from .constants import PY36
 from .dumpers import DumpMixin, setup_default_dumper, asdict
 from .loaders import LoadMixin, setup_default_loader, fromlist, fromdict
 from .models import (json_field, json_key, Container,
@@ -122,10 +121,3 @@
 # Setup the default type hooks to use when converting `dataclass` instances to
 # a JSON `string` or a Python `dict` object.
 setup_default_dumper()
-
-if PY36:    # pragma: no cover
-    # Python 3.6 requires a backport for `datetime.fromisoformat()`
-    # noinspection PyPackageRequirements
-    # noinspection PyUnresolvedReferences
-    from backports.datetime_fromisoformat import MonkeyPatch
-    MonkeyPatch.patch_fromisoformat()

dataclass_wizard/bases.py

@@ -134,6 +134,12 @@ class AbstractMeta(metaclass=ABCOrAndMeta):
     # apply in a recursive manner.
     recursive: ClassVar[bool] = True
 
+    # True to support cyclic or self-referential dataclasses. For example,
+    # the type of a dataclass field in class `A` refers to `A` itself.
+    #
+    # See https://github.com/rnag/dataclass-wizard/issues/62 for more details.
+    recursive_classes: ClassVar[bool] = False
+
     # True to raise an class:`UnknownJSONKey` when an unmapped JSON key is
     # encountered when `from_dict` or `from_json` is called; an unknown key is
     # one that does not have a known mapping to a dataclass field.

dataclass_wizard/bases_meta.py

@@ -14,6 +14,7 @@
     get_outer_class_name, get_class_name, create_new_class,
     json_field_to_dataclass_field, dataclass_field_to_json_field
 )
+from .constants import TAG
 from .decorators import try_with_load
 from .dumpers import get_dumper
 from .enums import LetterCase, DateTimeTo
@@ -173,10 +174,13 @@ def _as_enum_safe(cls, name: str, base_type: Type[E]) -> Optional[E]:
 # noinspection PyPep8Naming
 def LoadMeta(*, debug_enabled: bool = False,
              recursive: bool = True,
+             recursive_classes: bool = False,
              raise_on_unknown_json_key: bool = False,
              json_key_to_field: Dict[str, str] = None,
              key_transform: Union[LetterCase, str] = None,
-             tag: str = None) -> META:
+             tag: str = None,
+             tag_key: str = TAG,
+             auto_assign_tags: bool = False) -> META:
     """
     Helper function to setup the ``Meta`` Config for the JSON load
     (de-serialization) process, which is intended for use alongside the
@@ -198,11 +202,14 @@ def LoadMeta(*, debug_enabled: bool = False,
     base_dict = {
         '__slots__': (),
         'raise_on_unknown_json_key': raise_on_unknown_json_key,
+        'recursive_classes': recursive_classes,
         'key_transform_with_load': key_transform,
         'json_key_to_field': json_key_to_field,
         'debug_enabled': debug_enabled,
         'recursive': recursive,
         'tag': tag,
+        'tag_key': tag_key,
+        'auto_assign_tags': auto_assign_tags,
     }
 
     # Create a new subclass of :class:`AbstractMeta`

dataclass_wizard/class_helper.py

@@ -30,10 +30,8 @@
 
 # A cached mapping of a dataclass to each of its case-insensitive field names
 # and load hook.
-#
-# Note: need to create a `ForwardRef` here, because Python 3.6 complains.
 _FIELD_NAME_TO_LOAD_PARSER: Dict[
-    Type, 'DictWithLowerStore[str, AbstractParser]'] = {}
+    Type, DictWithLowerStore[str, AbstractParser]] = {}
 
 # Since the dump process doesn't use Parsers currently, we use a sentinel
 # mapping to confirm if we need to setup the dump config for a dataclass

dataclass_wizard/constants.py

@@ -8,18 +8,6 @@
 # Current system Python version
 _PY_VERSION = sys.version_info[:2]
 
-# Check if currently running Python 3.6
-PY36 = _PY_VERSION == (3, 6)
-
-# Check if currently running Python 3.8
-PY38 = _PY_VERSION == (3, 8)
-
-# Check if currently running Python 3.8 or higher
-PY38_OR_ABOVE = _PY_VERSION >= (3, 8)
-
-# Check if currently running Python 3.9
-PY39 = _PY_VERSION == (3, 9)
-
 # Check if currently running Python 3.10 or higher
 PY310_OR_ABOVE = _PY_VERSION >= (3, 10)
 

dataclass_wizard/decorators.py

@@ -148,15 +148,6 @@ def new_func(o: Any):
     return new_func
 
 
-def discard_kwargs(f):
-
-    @wraps(f)
-    def new_func(*args, **_kwargs):
-        return f(*args)
-
-    return new_func
-
-
 def _alias(default: Callable) -> Callable[[T], T]:
     """
     Decorator which re-assigns a function `_f` to point to `default` instead.