feat(DTO): deterministic transfer model names (#2389)

* feat(DTO): make transfer model names deterministic

---------

Signed-off-by: Janek Nouvertné <25355197+provinzkraut@users.noreply.github.com>

litestar/dto/_backend.py

@@ -3,7 +3,6 @@
 """
 from __future__ import annotations
 
-import secrets
 from dataclasses import replace
 from typing import TYPE_CHECKING, AbstractSet, Any, Callable, ClassVar, Collection, Final, Mapping, Union, cast
 
@@ -27,6 +26,7 @@
 from litestar.serialization import decode_json, decode_msgpack
 from litestar.types import Empty
 from litestar.typing import FieldDefinition
+from litestar.utils import unique_name_for_scope
 from litestar.utils.typing import safe_generic_origin_map
 
 if TYPE_CHECKING:
@@ -154,6 +154,18 @@ def parse_model(
             defined_fields.append(transfer_field_definition)
         return tuple(defined_fields)
 
+    def _create_transfer_model_name(self, model_name: str) -> str:
+        long_name_prefix = self.handler_id.split("::")[0]
+        short_name_prefix = _camelize(long_name_prefix.split(".")[-1], True)
+
+        name_suffix = "RequestBody" if self.is_data_field else "ResponseBody"
+
+        if (short_name := f"{short_name_prefix}{model_name}{name_suffix}") not in self._seen_model_names:
+            return short_name
+        if (long_name := f"{long_name_prefix}{model_name}{name_suffix}") not in self._seen_model_names:
+            return long_name
+        return unique_name_for_scope(long_name, self._seen_model_names)
+
     def create_transfer_model_type(
         self, model_name: str, field_definitions: tuple[TransferDTOFieldDefinition, ...]
     ) -> type[Struct]:
@@ -166,19 +178,9 @@ def create_transfer_model_type(
         Returns:
             A ``BackendT`` class.
         """
-        long_name_prefix = self.handler_id.split("::")[0]
-        short_name_prefix = _camelize(long_name_prefix.split(".")[-1], True)
-
-        name_suffix = "RequestBody" if self.is_data_field else "ResponseBody"
-
-        if f"{short_name_prefix}{model_name}{name_suffix}" not in self._seen_model_names:
-            struct_name = f"{short_name_prefix}{model_name}{name_suffix}"
-        elif f"{long_name_prefix}{model_name}{name_suffix}" not in self._seen_model_names:
-            struct_name = f"{long_name_prefix}{model_name}{name_suffix}"
-        else:
-            struct_name = f"{long_name_prefix}{model_name}{name_suffix}{secrets.token_hex(8)}"
-
+        struct_name = self._create_transfer_model_name(model_name)
         self._seen_model_names.add(struct_name)
+
         struct = _create_struct_for_field_definitions(struct_name, field_definitions)
         setattr(struct, "__schema_name__", struct_name)
         return struct

litestar/utils/__init__.py

@@ -1,6 +1,6 @@
 from litestar.utils.deprecation import deprecated, warn_deprecation
 
-from .helpers import Ref, get_enum_string_value, get_name, url_quote
+from .helpers import Ref, get_enum_string_value, get_name, unique_name_for_scope, url_quote
 from .path import join_paths, normalize_path
 from .predicates import (
     is_annotated_type,
@@ -75,6 +75,7 @@
     "normalize_path",
     "set_litestar_scope_state",
     "unique",
+    "unique_name_for_scope",
     "url_quote",
     "warn_deprecation",
 )

litestar/utils/helpers.py

@@ -6,6 +6,7 @@
 from urllib.parse import quote
 
 if TYPE_CHECKING:
+    from collections.abc import Container
     from typing import Iterable
 
     from litestar.datastructures import Cookie
@@ -18,6 +19,7 @@
     "get_name",
     "unwrap_partial",
     "url_quote",
+    "unique_name_for_scope",
 )
 
 T = TypeVar("T")
@@ -99,3 +101,12 @@ def url_quote(value: str | bytes) -> str:
         A quoted URL.
     """
     return quote(value, safe="/#%[]=:;$&()+,!?*@'~")
+
+
+def unique_name_for_scope(base_name: str, scope: Container[str]) -> str:
+    """Create a name derived from ``base_name`` that's unique within ``scope``"""
+    i = 0
+    while True:
+        if (unique_name := f"{base_name}_{i}") not in scope:
+            return unique_name
+        i += 1

tests/unit/test_utils/test_helpers.py

@@ -1,6 +1,6 @@
 from functools import partial
 
-from litestar.utils.helpers import unwrap_partial
+from litestar.utils.helpers import unique_name_for_scope, unwrap_partial
 
 
 def test_unwrap_partial() -> None:
@@ -11,3 +11,11 @@ def func(*args: int) -> int:
 
     assert wrapped() == 3
     assert unwrap_partial(wrapped) is func
+
+
+def test_unique_name_for_scope() -> None:
+    assert unique_name_for_scope("a", []) == "a_0"
+
+    assert unique_name_for_scope("a", ["a", "a_0", "b"]) == "a_1"
+
+    assert unique_name_for_scope("b", ["a", "a_0", "b"]) == "b_0"