add partial date type

mex/common/types/__init__.py

@@ -44,6 +44,7 @@
     VocabularyLoader,
     split_to_caps,
 )
+from mex.common.types.year_month import YearMonth
 
 __all__ = (
     "AccessPlatformID",
@@ -90,4 +91,5 @@
     "VocabularyEnum",
     "VocabularyLoader",
     "WorkPath",
+    "YearMonth",
 )

mex/common/types/year_month.py

@@ -0,0 +1,27 @@
+from typing import Any, Type
+
+from pydantic import GetJsonSchemaHandler
+from pydantic.json_schema import JsonSchemaValue
+from pydantic_core import core_schema
+
+YEAR_MONTH_PATTERN = r"^\d{4}(-\d{2})?$"
+
+
+class YearMonth(str):
+    """Partial date pattern that accepts YYYY or YYYY-MM format."""
+
+    @classmethod
+    def __get_pydantic_core_schema__(cls, _source: Type[Any]) -> core_schema.CoreSchema:
+        """Get pydantic core schema."""
+        return core_schema.str_schema(pattern=YEAR_MONTH_PATTERN)
+
+    @classmethod
+    def __get_pydantic_json_schema__(
+        cls, core_schema_: core_schema.CoreSchema, handler: GetJsonSchemaHandler
+    ) -> JsonSchemaValue:
+        """Add title and format."""
+        field_schema = handler(core_schema_)
+        field_schema = handler.resolve_ref_schema(field_schema)
+        field_schema["title"] = cls.__name__
+        field_schema["examples"] = ["2024", "1999-04"]
+        return field_schema