Use Sequence instead of list for tables and columns

The List type is considered immutable, which means polymorphism does
not work for typing. Instead use the Sequence type which is not
considered immutable and accepts child classes in the declaration.

python/felis/datamodel.py

@@ -22,7 +22,7 @@
 import logging
 from collections.abc import Mapping
 from enum import Enum
-from typing import Any, Literal
+from typing import Any, Literal, Sequence
 
 from astropy import units as units  # type: ignore
 from astropy.io.votable import ucd  # type: ignore
@@ -243,7 +243,7 @@ class ForeignKeyConstraint(Constraint):
 class Table(BaseObject):
     """A database table."""
 
-    columns: list[Column]
+    columns: Sequence[Column]
     """The columns in the table."""
 
     constraints: list[Constraint] = Field(default_factory=list)
@@ -373,7 +373,7 @@ class Schema(BaseObject):
     version: SchemaVersion | str | None = None
     """The version of the schema."""
 
-    tables: list[Table]
+    tables: Sequence[Table]
     """The tables in the schema."""
 
     id_map: dict[str, Any] = Field(default_factory=dict, exclude=True)

python/felis/validation.py

@@ -20,7 +20,7 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 import logging
-from typing import Any, Type
+from typing import Any, Sequence, Type
 
 from pydantic import Field, model_validator
 
@@ -51,7 +51,7 @@ class RspTable(Table):
     tap_table_index: int = Field(..., alias="tap:table_index")
     """Redefine the TAP_SCHEMA table index so that it is required."""
 
-    columns: list[RspColumn]  # type: ignore
+    columns: Sequence[RspColumn]
     """Redefine columns to include RSP validation."""
 
     @model_validator(mode="after")  # type: ignore
@@ -74,7 +74,7 @@ class RspSchema(Schema):
     """Redefine description to make it required and non-empty.
     """
 
-    tables: list[RspTable]  # type: ignore
+    tables: Sequence[RspTable]
     """Redefine tables to include RSP validation."""
 
     @model_validator(mode="after")  # type: ignore

tests/test_validation.py

@@ -98,7 +98,8 @@ def test_rsp_validation(self) -> None:
         with self.assertRaises(ValidationError):
             RspSchema(tables=[tbl])
 
-        # Creating a schema with duplicate TAP table indices should throw an exception.
+        # Creating a schema with duplicate TAP table indices should throw an
+        # exception.
         with self.assertRaises(ValidationError):
             RspSchema(
                 **{"name": "testSchema", "@id": "#test_schema_id", "description": "test schema"},