Cache calculated field_aliases for a schema

litestar/openapi/spec/schema.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field, fields, is_dataclass
-from typing import TYPE_CHECKING, Any, Hashable, Mapping, Sequence
+from typing import TYPE_CHECKING, Any, Hashable, Mapping, Sequence, cast
 
 from litestar.openapi.spec.base import BaseSchemaObject
 from litestar.utils.predicates import is_non_string_sequence
@@ -649,10 +649,13 @@ def __hash__(self) -> int:
 
     @classmethod
     def field_aliases(cls) -> dict[str, str]:
+        if hasattr(cls, "_field_aliases"):
+            return cast("dict[str, str]", cls._field_aliases)
         retval = {}
         for field_def in fields(cls):
             if field_def.metadata is not None and (field_alias := field_def.metadata.get("alias")):
                 retval[field_alias] = field_def.name
+        cls._field_aliases = retval
         return retval