[pydantic#12] add pendulum dt support

pydantic_extra_types/pendulum_dt.py

@@ -0,0 +1,40 @@
+try:
+    from pendulum import DateTime as _DateTime
+    from pendulum import parse
+except ModuleNotFoundError:  # pragma: no cover
+    raise RuntimeError(
+        'The `pendulum_dt` module requires "pendulum" to be installed. You can install it with "pip install pendulum".'
+    )
+from typing import Any, List, Type
+
+from pydantic import GetCoreSchemaHandler
+from pydantic_core import PydanticCustomError, core_schema
+
+
+class DateTime(_DateTime):
+    """
+    A pendulum.DateTime object.
+    At runtime, this type decomposes into pendulum.DateTime automagically.
+    This type exists because Pydantic throws a fit on unknown types.
+    """
+
+    __slots__: List[str] = []
+
+    @classmethod
+    def __get_pydantic_core_schema__(cls, source: Type[Any], handler: GetCoreSchemaHandler) -> core_schema.CoreSchema:
+        return core_schema.no_info_wrap_validator_function(
+            cls._validate_datetime, core_schema.is_instance_schema(_DateTime)
+        )
+
+    @classmethod
+    def _validate_datetime(cls, value: Any, handler: core_schema.ValidatorFunctionWrapHandler) -> Any:
+        # if we are passed an existing instance, pass it straight through.
+        if isinstance(value, _DateTime):
+            return handler(value)
+
+        # otherwise, parse it.
+        try:
+            data = parse(value)
+        except Exception as exc:
+            raise PydanticCustomError('value_error', 'value is not a valid timestamp') from exc
+        return handler(data)

tests/test_pendulum_dt.py

@@ -0,0 +1,39 @@
+import pendulum
+import pytest
+from pydantic import BaseModel, ValidationError
+
+from pydantic_extra_types.pendulum_dt import DateTime
+
+
+class Model(BaseModel):
+    dt: DateTime
+
+
+def test_pendulum_dt_existing_instance():
+    """
+    Verifies that constructing a model with an existing pendulum dt doesn't throw.
+    """
+    now = pendulum.now()
+    model = Model(dt=now)
+    assert model.dt == now
+
+
+@pytest.mark.parametrize(
+    'dt', [pendulum.now().to_iso8601_string(), pendulum.now().to_w3c_string(), pendulum.now().to_iso8601_string()]
+)
+def test_pendulum_dt_from_serialized(dt):
+    """
+    Verifies that building an instance from serialized, well-formed strings decode properly.
+    """
+    dt_actual = pendulum.parse(dt)
+    model = Model(dt=dt)
+    assert model.dt == dt_actual
+
+
+@pytest.mark.parametrize('dt', [None, 'malformed', pendulum.now().to_iso8601_string()[:5], 42])
+def test_pendulum_dt_malformed(dt):
+    """
+    Verifies that the instance fails to validate if malformed dt are passed.
+    """
+    with pytest.raises(ValidationError):
+        Model(dt=dt)