Merge pull request #239 from jacebrowning/union-types

Support optionals via union types

.pylint.ini

@@ -36,6 +36,7 @@ disable=
     cell-var-from-loop,
     cyclic-import,
     comparison-with-callable,
+    unsupported-binary-operation,
 
 init-import=yes
 

.travis.yml

@@ -22,8 +22,9 @@ install:
 script:
   - make test-repeat
   - make check
-  - make notebooks
-  - make mkdocs
+  # TODO: Get targets working with Python 3.10
+  # - make notebooks
+  # - make mkdocs
 
 after_success:
   - pip install coveralls

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 1.1 (beta)
+
+- Added support for Python 3.10's builtin optional types (e.g. `int | None`).
+
 # 1.0 (2021-10-04)
 
 - Initial stable release.

datafiles/converters/__init__.py

@@ -1,5 +1,6 @@
 import dataclasses
 import inspect
+import types
 from enum import Enum
 from inspect import isclass
 from typing import Any, Dict, Mapping, Optional, Union
@@ -65,6 +66,14 @@ def map_type(cls, *, name: str = '', item_cls: Optional[type] = None):
         log.debug(f'Mapped {cls!r} to new converter: {converter}')
         return converter
 
+    if hasattr(types, 'UnionType') and isinstance(cls, types.UnionType):  # type: ignore
+        # Python 3.10 behavior
+        converter = map_type(cls.__args__[0])
+        assert len(cls.__args__) == 2
+        assert cls.__args__[1] == type(None)
+        converter = converter.as_optional()
+        return converter
+
     cls = resolve(cls)
 
     if hasattr(cls, '__origin__'):

datafiles/tests/__init__.py

@@ -1 +1,11 @@
 """Unit tests for the package."""
+
+import sys
+
+import pytest
+
+
+xfail_without_pep_604 = pytest.mark.xfail(
+    sys.version_info < (3, 10),
+    reason="Union types (PEP 604) are not available in Python 3.9 and earlier",
+)

datafiles/tests/test_converters.py

@@ -9,6 +9,8 @@
 
 from datafiles import converters, settings
 
+from . import xfail_without_pep_604
+
 
 @dataclass
 class MyDataclass:
@@ -102,7 +104,14 @@ def it_handles_enums(expect):
         converter = converters.map_type(Color)
         expect(converter.__name__) == 'ColorConverter'
 
+    @xfail_without_pep_604
     def it_handles_optionals(expect):
+        converter = converters.map_type(str | None)  # type: ignore
+        expect(converter.__name__) == 'OptionalString'
+        expect(converter.TYPE) == str
+        expect(converter.DEFAULT).is_(None)
+
+    def it_handles_optionals_with_legacy_syntax(expect):
         converter = converters.map_type(Optional[str])
         expect(converter.__name__) == 'OptionalString'
         expect(converter.TYPE) == str

pyproject.toml

@@ -1,7 +1,7 @@
 [tool.poetry]
 
 name = "datafiles"
-version = "1.0"
+version = "1.1b1"
 description = "File-based ORM for dataclasses."
 
 license = "MIT"
@@ -65,8 +65,7 @@ black = "=21.9b0"
 isort = "=5.9.2"
 
 # Linters
-mypy = "~0.790"
-typed_ast = "^1.4.3" # updated mypy dependency for Python 3.10
+mypy = "~0.910"
 pylint = "~2.7.4"
 pydocstyle = "*"
 
@@ -85,7 +84,7 @@ pytest-profiling = "*"
 coveragespace = "^4.0"
 
 # Documentation
-mkdocs = "~1.0"
+mkdocs = "~1.0.4"
 pygments = "^2.9"
 
 # Notebooks