Add Annotated support and therefore set minimum python version as 3.9

Author: mvanderlee

.github/workflows/python-package.yml

@@ -12,10 +12,10 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest"]
-        python_version: ["3.7", "3.8", "3.9", "3.10", "3.11", "pypy3.10"]
+        python_version: ["3.9", "3.10", "3.11", "3.12", "pypy3.10"]
         include:
           - os: "ubuntu-20.04"
-            python_version: "3.6"
+            python_version: "3.9"
 
     runs-on: ${{ matrix.os }}
     steps:

.pre-commit-config.yaml

@@ -3,7 +3,7 @@ repos:
   rev: v3.3.1
   hooks:
   - id: pyupgrade
-    args: ["--py36-plus"]
+    args: ["--py37-plus"]
 - repo: https://github.com/python/black
   rev: 23.1.0
   hooks:

.vscode/settings.json

@@ -0,0 +1,8 @@
+{
+  "python.testing.pytestArgs": [
+    "-W",
+    "ignore",
+    "-vv",
+    "tests"
+],
+}

README.md

@@ -247,28 +247,25 @@ class Sample:
 
 See [marshmallow's documentation about extending `Schema`](https://marshmallow.readthedocs.io/en/stable/extending.html).
 
-### Custom NewType declarations
+### Custom type declarations
 
-This library exports a `NewType` function to create types that generate [customized marshmallow fields](https://marshmallow.readthedocs.io/en/stable/custom_fields.html#creating-a-field-class).
-
-Keyword arguments to `NewType` are passed to the marshmallow field constructor.
+This library allows you to specify [customized marshmallow fields](https://marshmallow.readthedocs.io/en/stable/custom_fields.html#creating-a-field-class) using python's Annoted type [PEP-593](https://peps.python.org/pep-0593/).
 
 ```python
-import marshmallow.validate
-from marshmallow_dataclass import NewType
+from typing import Annotated
+import marshmallow.fields as mf
+import marshmallow.validate as mv
 
-IPv4 = NewType(
-    "IPv4", str, validate=marshmallow.validate.Regexp(r"^([0-9]{1,3}\\.){3}[0-9]{1,3}$")
-)
+IPv4 = Annotated[str, mf.String(validate=mv.Regexp(r"^([0-9]{1,3}\\.){3}[0-9]{1,3}$"))]
 ```
 
-You can also pass a marshmallow field to `NewType`.
+You can also pass a marshmallow field class.
 
 ```python
 import marshmallow
 from marshmallow_dataclass import NewType
 
-Email = NewType("Email", str, field=marshmallow.fields.Email)
+Email = Annotated[str, marshmallow.fields.Email]
 ```
 
 For convenience, some custom types are provided:

marshmallow_dataclass/__init__.py

@@ -43,40 +43,32 @@ class User:
 import warnings
 from enum import Enum
 from functools import lru_cache, partial
+from typing import Annotated, Any, Callable, Dict, FrozenSet, List, Mapping
+from typing import NewType as typing_NewType
 from typing import (
-    Any,
-    Callable,
-    Dict,
-    List,
-    Mapping,
-    NewType as typing_NewType,
     Optional,
+    Sequence,
     Set,
     Tuple,
     Type,
     TypeVar,
     Union,
     cast,
+    get_args,
+    get_origin,
     get_type_hints,
     overload,
-    Sequence,
-    FrozenSet,
 )
 
 import marshmallow
 import typing_inspect
 
 from marshmallow_dataclass.lazy_class_attribute import lazy_class_attribute
 
-
 if sys.version_info >= (3, 11):
     from typing import dataclass_transform
-elif sys.version_info >= (3, 7):
-    from typing_extensions import dataclass_transform
 else:
-    # @dataclass_transform() only helps us with mypy>=1.1 which is only available for python>=3.7
-    def dataclass_transform(**kwargs):
-        return lambda cls: cls
+    from typing_extensions import dataclass_transform
 
 
 __all__ = ["dataclass", "add_schema", "class_schema", "field_for_schema", "NewType"]
@@ -431,7 +423,9 @@ def _internal_class_schema(
 
     # Update the schema members to contain marshmallow fields instead of dataclass fields
     type_hints = get_type_hints(
-        clazz, localns=clazz_frame.f_locals if clazz_frame else None
+        clazz,
+        localns=clazz_frame.f_locals if clazz_frame else None,
+        include_extras=True,
     )
     attributes.update(
         (
@@ -527,12 +521,27 @@ def _field_for_generic_type(
     """
     If the type is a generic interface, resolve the arguments and construct the appropriate Field.
     """
-    origin = typing_inspect.get_origin(typ)
-    arguments = typing_inspect.get_args(typ, True)
+    origin = get_origin(typ)
+    arguments = get_args(typ)
     if origin:
         # Override base_schema.TYPE_MAPPING to change the class used for generic types below
         type_mapping = base_schema.TYPE_MAPPING if base_schema else {}
 
+        if origin is Annotated:
+            marshmallow_annotations = [
+                arg
+                for arg in arguments[1:]
+                if (inspect.isclass(arg) and issubclass(arg, marshmallow.fields.Field))
+                or isinstance(arg, marshmallow.fields.Field)
+            ]
+            if marshmallow_annotations:
+                field = marshmallow_annotations[-1]
+                # Got a field instance, return as is. User must know what they're doing
+                if isinstance(field, marshmallow.fields.Field):
+                    return field
+
+                return field(**metadata)
+
         if origin in (list, List):
             child_type = field_for_schema(
                 arguments[0], base_schema=base_schema, typ_frame=typ_frame
@@ -684,6 +693,7 @@ def field_for_schema(
         metadata.setdefault("allow_none", True)
         return marshmallow.fields.Raw(**metadata)
 
+    # i.e.: Literal['abc']
     if typing_inspect.is_literal_type(typ):
         arguments = typing_inspect.get_args(typ)
         return marshmallow.fields.Raw(
@@ -695,6 +705,7 @@ def field_for_schema(
             **metadata,
         )
 
+    # i.e.: Final[str] = 'abc'
     if typing_inspect.is_final_type(typ):
         arguments = typing_inspect.get_args(typ)
         if arguments:
@@ -749,13 +760,7 @@ def field_for_schema(
 
     # enumerations
     if issubclass(typ, Enum):
-        try:
-            return marshmallow.fields.Enum(typ, **metadata)
-        except AttributeError:
-            # Remove this once support for python 3.6 is dropped.
-            import marshmallow_enum
-
-            return marshmallow_enum.EnumField(typ, **metadata)
+        return marshmallow.fields.Enum(typ, **metadata)
 
     # Nested marshmallow dataclass
     # it would be just a class name instead of actual schema util the schema is not ready yet
@@ -818,7 +823,8 @@ def NewType(
     field: Optional[Type[marshmallow.fields.Field]] = None,
     **kwargs,
 ) -> Callable[[_U], _U]:
-    """NewType creates simple unique types
+    """DEPRECATED: Use typing.Annotated instead.
+    NewType creates simple unique types
     to which you can attach custom marshmallow attributes.
     All the keyword arguments passed to this function will be transmitted
     to the marshmallow field constructor.

marshmallow_dataclass/typing.py

@@ -1,8 +1,9 @@
+from typing import Annotated
+
 import marshmallow.fields
-from . import NewType
 
-Url = NewType("Url", str, field=marshmallow.fields.Url)
-Email = NewType("Email", str, field=marshmallow.fields.Email)
+Url = Annotated[str, marshmallow.fields.Url]
+Email = Annotated[str, marshmallow.fields.Email]
 
 # Aliases
 URL = Url

setup.py

@@ -8,23 +8,15 @@
     "Operating System :: OS Independent",
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python",
-    "Programming Language :: Python :: 3.6",
-    "Programming Language :: Python :: 3.7",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Topic :: Internet :: WWW/HTTP :: Dynamic Content :: CGI Tools/Libraries",
 ]
 
 EXTRAS_REQUIRE = {
-    "enum": [
-        "marshmallow-enum; python_version < '3.7'",
-        "marshmallow>=3.18.0,<4.0; python_version >= '3.7'",
-    ],
     "union": ["typeguard>=2.4.1,<4.0.0"],
     "lint": ["pre-commit~=2.17"],
-    ':python_version == "3.6"': ["dataclasses", "types-dataclasses<0.6.4"],
     "docs": ["sphinx"],
     "tests": [
         "pytest>=5.4",
@@ -34,8 +26,7 @@
     ],
 }
 EXTRAS_REQUIRE["dev"] = (
-    EXTRAS_REQUIRE["enum"]
-    + EXTRAS_REQUIRE["union"]
+    EXTRAS_REQUIRE["union"]
     + EXTRAS_REQUIRE["lint"]
     + EXTRAS_REQUIRE["docs"]
     + EXTRAS_REQUIRE["tests"]
@@ -56,14 +47,11 @@
     keywords=["marshmallow", "dataclass", "serialization"],
     classifiers=CLASSIFIERS,
     license="MIT",
-    python_requires=">=3.6",
+    python_requires=">=3.9",
     install_requires=[
-        "marshmallow>=3.13.0,<4.0",
+        "marshmallow>=3.18.0,<4.0",
         "typing-inspect>=0.8.0,<1.0",
-        # Need `Literal`
-        "typing-extensions>=3.7.2; python_version < '3.8'",
         # Need `dataclass_transform(field_specifiers)`
-        # NB: typing-extensions>=4.2.0 conflicts with python 3.6
         "typing-extensions>=4.2.0; python_version<'3.11' and python_version>='3.7'",
     ],
     extras_require=EXTRAS_REQUIRE,

tests/test_annotated.py

@@ -0,0 +1,31 @@
+import unittest
+from typing import Annotated, Optional
+
+import marshmallow
+import marshmallow.fields
+
+from marshmallow_dataclass import dataclass
+
+
+class TestAnnotatedField(unittest.TestCase):
+    def test_annotated_field(self):
+        @dataclass
+        class AnnotatedValue:
+            value: Annotated[str, marshmallow.fields.Email]
+            default_string: Annotated[
+                Optional[str], marshmallow.fields.String(missing="Default String")
+            ] = None
+
+        schema = AnnotatedValue.Schema()
+
+        self.assertEqual(
+            schema.load({"value": "test@test.com"}),
+            AnnotatedValue(value="test@test.com", default_string="Default String"),
+        )
+        self.assertEqual(
+            schema.load({"value": "test@test.com", "default_string": "override"}),
+            AnnotatedValue(value="test@test.com", default_string="override"),
+        )
+
+        with self.assertRaises(marshmallow.exceptions.ValidationError):
+            schema.load({"value": "notavalidemail"})

tests/test_mypy.yml

@@ -6,7 +6,7 @@
     follow_imports = silent
     plugins = marshmallow_dataclass.mypy
     show_error_codes = true
-    python_version = 3.6
+    python_version = 3.9
   env:
     - PYTHONPATH=.
   main: |