Simplify handling of nullability in ColumnSpecs.

python/lsst/daf/butler/column_spec.py

@@ -29,8 +29,6 @@
 
 __all__ = (
     "ColumnSpec",
-    "not_nullable",
-    "default_nullable",
     "IntColumnSpec",
     "StringColumnSpec",
     "HashColumnSpec",
@@ -62,16 +60,9 @@ class _BaseColumnSpec(_BaseModelCompat, ABC):
 
     type: str
 
-    nullable: bool | None = pydantic.Field(
-        default=None,
-        description=textwrap.dedent(
-            """\
-            Whether the column may be ``NULL``.
-
-            The default (represented by `None`) is context-dependent; some
-            fields are ``NOT NULL``, while oethers default to nullable.
-            """
-        ),
+    nullable: bool = pydantic.Field(
+        default=True,
+        description="Whether the column may be ``NULL``.",
     )
 
     def to_sql_spec(self, **kwargs: Any) -> ddl.FieldSpec:
@@ -133,46 +124,6 @@ def __str__(self) -> str:
         return "\n".join(self.display())
 
 
-def not_nullable(c: _BaseColumnSpec) -> _BaseColumnSpec:
-    """Pydantic validator for `ColumnSpec` that requires
-    `ColumnSpec.nullable` to be `False`, and replaces `None` with `False`.
-
-    Parameters
-    ----------
-    c : `ColumnSpec`
-        Original column specification.
-
-    Returns
-    -------
-    c : `ColumnSpec`
-        The object passed in, modified in-place.
-    """
-    if c.nullable is True:
-        raise ValueError("Key columns may not be nullable.")
-    c.nullable = False
-    return c
-
-
-def default_nullable(c: _BaseColumnSpec) -> _BaseColumnSpec:
-    """Pydantic validator for `ColumnSpec` that allows
-    `ColumnSpec.nullable` to be `True` or `False` and replaces `None` with
-    `True`.
-
-    Parameters
-    ----------
-    c : `ColumnSpec`
-        Original column specification.
-
-    Returns
-    -------
-    c : `ColumnSpec`
-        The object passed in, modified in-place.
-    """
-    if c.nullable is None:
-        c.nullable = True
-    return c
-
-
 @final
 class IntColumnSpec(_BaseColumnSpec):
     """Description of an integer column."""
@@ -183,7 +134,6 @@ class IntColumnSpec(_BaseColumnSpec):
 
     def to_arrow(self) -> arrow_utils.ToArrow:
         # Docstring inherited.
-        assert self.nullable is not None, "nullable=None should be resolved by validators"
         return arrow_utils.ToArrow.for_primitive(self.name, pa.uint64(), nullable=self.nullable)
 
 
@@ -204,7 +154,6 @@ def to_sql_spec(self, **kwargs: Any) -> ddl.FieldSpec:
 
     def to_arrow(self) -> arrow_utils.ToArrow:
         # Docstring inherited.
-        assert self.nullable is not None, "nullable=None should be resolved by validators"
         return arrow_utils.ToArrow.for_primitive(self.name, pa.string(), nullable=self.nullable)
 
 
@@ -225,7 +174,6 @@ def to_sql_spec(self, **kwargs: Any) -> ddl.FieldSpec:
 
     def to_arrow(self) -> arrow_utils.ToArrow:
         # Docstring inherited.
-        assert self.nullable is not None, "nullable=None should be resolved by validators"
         return arrow_utils.ToArrow.for_primitive(
             self.name,
             # The size for Arrow binary columns is a fixed size, not a maximum
@@ -259,7 +207,6 @@ class BoolColumnSpec(_BaseColumnSpec):
 
     def to_arrow(self) -> arrow_utils.ToArrow:
         # Docstring inherited.
-        assert self.nullable is not None, "nullable=None should be resolved by validators"
         return arrow_utils.ToArrow.for_primitive(self.name, pa.bool_(), nullable=self.nullable)
 
 
@@ -294,7 +241,6 @@ class TimespanColumnSpec(_BaseColumnSpec):
 
     def to_arrow(self) -> arrow_utils.ToArrow:
         # Docstring inherited.
-        assert self.nullable is not None, "nullable=None should be resolved by validators"
         return arrow_utils.ToArrow.for_timespan(self.name, nullable=self.nullable)
 
 

python/lsst/daf/butler/dimensions/_config.py

@@ -31,15 +31,14 @@
 
 import warnings
 from collections.abc import Iterator, Mapping, Sequence
-from typing import Annotated, Any, TypeAlias
+from typing import Any
 
 import pydantic
 from lsst.resources import ResourcePath, ResourcePathExpression
 
 from .._compat import PYDANTIC_V2
 from .._config import Config, ConfigSubset
 from .._topology import TopologicalSpace
-from ..column_spec import default_nullable, not_nullable
 from ._database import (
     DatabaseDimensionElementConstructionVisitor,
     DatabaseTopologicalFamilyConstructionVisitor,
@@ -54,21 +53,6 @@
 # have a version.
 _DEFAULT_NAMESPACE = "daf_butler"
 
-if PYDANTIC_V2:
-    AnnotatedKeyColumnSpec: TypeAlias = Annotated[
-        KeyColumnSpec, pydantic.Field(discriminator="type"), pydantic.AfterValidator(not_nullable)
-    ]
-    AnnotatedMetadataColumnSpec: TypeAlias = Annotated[
-        MetadataColumnSpec, pydantic.Field(discriminator="type"), pydantic.AfterValidator(default_nullable)
-    ]
-else:
-
-    class _KeyColumnModel(pydantic.BaseModel):
-        spec: KeyColumnSpec = pydantic.Field(discriminator="type")
-
-    class _MetadataColumnModel(pydantic.BaseModel):
-        spec: MetadataColumnSpec = pydantic.Field(discriminator="type")
-
 
 class DimensionConfig(ConfigSubset):
     """Configuration that defines a `DimensionUniverse`.
@@ -214,24 +198,26 @@ def _extractElementVisitors(self) -> Iterator[DimensionConstructionVisitor]:
             # MyPy is confused by the typing.Annotated usage and/or how
             # Pydantic annotated TypeAdapter.
             key_adapter: pydantic.TypeAdapter[KeyColumnSpec] = pydantic.TypeAdapter(  # type: ignore
-                AnnotatedKeyColumnSpec  # type: ignore
+                KeyColumnSpec  # type: ignore
             )
             validate_key = key_adapter.validate_python
             metadata_adapter: pydantic.TypeAdapter[MetadataColumnSpec] = pydantic.TypeAdapter(  # type: ignore
-                AnnotatedMetadataColumnSpec  # type: ignore
+                MetadataColumnSpec  # type: ignore
             )
             validate_metadata = metadata_adapter.validate_python
         else:
 
             def validate_key(value: Any) -> KeyColumnSpec:  # type: ignore[misc]
-                return not_nullable(_KeyColumnModel(spec=value).spec)  # type: ignore[return-value]
+                return pydantic.parse_obj_as(KeyColumnSpec, value)  # type: ignore
 
             def validate_metadata(value: Any) -> MetadataColumnSpec:  # type: ignore[misc]
-                return default_nullable(_MetadataColumnModel(spec=value).spec)  # type: ignore[return-value]
+                return pydantic.parse_obj_as(MetadataColumnSpec, value)  # type: ignore
 
         for name, subconfig in self["elements"].items():
             metadata_columns = [validate_metadata(c) for c in subconfig.get("metadata", ())]
             unique_keys = [validate_key(c) for c in subconfig.get("keys", ())]
+            for unique_key in unique_keys:
+                unique_key.nullable = False
             if subconfig.get("governor", False):
                 unsupported = {"required", "implied", "viewOf", "alwaysJoin"}
                 if not unsupported.isdisjoint(subconfig.keys()):

python/lsst/daf/butler/dimensions/_elements.py

@@ -34,8 +34,9 @@
 )
 
 from abc import abstractmethod
-from typing import TYPE_CHECKING, Any, ClassVar, TypeAlias, Union, cast
+from typing import TYPE_CHECKING, Annotated, Any, ClassVar, TypeAlias, Union, cast
 
+import pydantic
 from lsst.utils.classes import cached_getter
 
 from .. import arrow_utils, column_spec, ddl
@@ -52,18 +53,24 @@
     from ._schema import DimensionRecordSchema
     from ._universe import DimensionUniverse
 
-KeyColumnSpec: TypeAlias = Union[
-    column_spec.IntColumnSpec,
-    column_spec.StringColumnSpec,
-    column_spec.HashColumnSpec,
+KeyColumnSpec: TypeAlias = Annotated[
+    Union[
+        column_spec.IntColumnSpec,
+        column_spec.StringColumnSpec,
+        column_spec.HashColumnSpec,
+    ],
+    pydantic.Field(discriminator="type"),
 ]
 
-MetadataColumnSpec: TypeAlias = Union[
-    column_spec.IntColumnSpec,
-    column_spec.StringColumnSpec,
-    column_spec.FloatColumnSpec,
-    column_spec.HashColumnSpec,
-    column_spec.BoolColumnSpec,
+MetadataColumnSpec: TypeAlias = Annotated[
+    Union[
+        column_spec.IntColumnSpec,
+        column_spec.StringColumnSpec,
+        column_spec.FloatColumnSpec,
+        column_spec.HashColumnSpec,
+        column_spec.BoolColumnSpec,
+    ],
+    pydantic.Field(discriminator="type"),
 ]