fix(fastapi): update pydantic utilities

fern/pages/changelogs/fastapi/2024-12-09.mdx

@@ -0,0 +1,15 @@
+## 1.6.0
+**`(fix):`** The FastAPI generator now supports a new mode for pydantic model generation,
+to use pydantic v1 on v2 versions. 
+
+```yml generators.yml
+generators: 
+  server: 
+    - name: fernapi/fern-fastapi-server
+      version: 1.6.0
+      config: 
+        pydantic: 
+          version: "v1_on_v2"
+````
+
+

fern/pages/changelogs/python-sdk/2024-12-08.mdx

@@ -0,0 +1,4 @@
+## 4.3.9
+**`(fix):`** Fix indentation in generated README.md sections to ensure proper formatting and readability.
+
+

generators/python/core_utilities/shared/with_pydantic_v1_on_v2/pydantic_utilities.py

@@ -1,3 +1,5 @@
+# This file was auto-generated by Fern from our API Definition.
+
 # nopycln: file
 import datetime as dt
 import typing
@@ -7,37 +9,42 @@
 
 import pydantic
 
-from .datetime_utils import serialize_datetime
-from .serialization import convert_and_respect_annotation_metadata
-
 IS_PYDANTIC_V2 = pydantic.VERSION.startswith("2.")
 
-from pydantic.datetime_parse import (
-    parse_date as parse_date,  # type: ignore # Pydantic v1
+from .datetime_utils import serialize_datetime
+
+# isort will try to reformat the comments on these imports, which breaks mypy
+# isort: off
+from pydantic.v1.datetime_parse import (  # type: ignore # pyright: ignore[reportMissingImports] # Pydantic v2
+    parse_date as parse_date,
+)
+from pydantic.v1.datetime_parse import (  # pyright: ignore[reportMissingImports] # Pydantic v2
+    parse_datetime as parse_datetime,
 )
-from pydantic.datetime_parse import (
-    parse_datetime as parse_datetime,  # type: ignore # Pydantic v1
+from pydantic.v1.json import (  # type: ignore # pyright: ignore[reportMissingImports] # Pydantic v2
+    ENCODERS_BY_TYPE as encoders_by_type,
 )
-from pydantic.fields import ModelField as ModelField  # type: ignore # Pydantic v1
-from pydantic.json import (
-    ENCODERS_BY_TYPE as encoders_by_type,  # type: ignore # Pydantic v1
+from pydantic.v1.typing import (  # type: ignore # pyright: ignore[reportMissingImports] # Pydantic v2
+    get_args as get_args,
 )
-from pydantic.typing import get_args as get_args  # type: ignore # Pydantic v1
-from pydantic.typing import get_origin as get_origin  # type: ignore # Pydantic v1
-from pydantic.typing import (
-    is_literal_type as is_literal_type,  # type: ignore # Pydantic v1
+from pydantic.v1.typing import (  # pyright: ignore[reportMissingImports] # Pydantic v2
+    get_origin as get_origin,
 )
-from pydantic.typing import is_union as is_union  # type: ignore # Pydantic v1
+from pydantic.v1.typing import (  # pyright: ignore[reportMissingImports] # Pydantic v2
+    is_literal_type as is_literal_type,
+)
+from pydantic.v1.typing import (  # pyright: ignore[reportMissingImports] # Pydantic v2
+    is_union as is_union,
+)
+from pydantic.v1.fields import ModelField as ModelField  # type: ignore # pyright: ignore[reportMissingImports] # Pydantic v2
 
-# isort: on
 
 T = typing.TypeVar("T")
 Model = typing.TypeVar("Model", bound=pydantic.BaseModel)
 
 
 def parse_obj_as(type_: typing.Type[T], object_: typing.Any) -> T:
-    dealiased_object = convert_and_respect_annotation_metadata(object_=object_, annotation=type_, direction="read")
-    return pydantic.parse_obj_as(type_, dealiased_object)
+    return pydantic.v1.parse_obj_as(type_, object_)
 
 
 def to_jsonable_with_fallback(
@@ -48,22 +55,12 @@ def to_jsonable_with_fallback(
 
 class UniversalBaseModel(pydantic.v1.BaseModel):
     class Config:
+        populate_by_name = True
         smart_union = True
+        allow_population_by_field_name = True
         json_encoders = {dt.datetime: serialize_datetime}
-
-    @classmethod
-    def model_construct(
-        cls: typing.Type["Model"], _fields_set: typing.Optional[typing.Set[str]] = None, **values: typing.Any
-    ) -> "Model":
-        dealiased_object = convert_and_respect_annotation_metadata(object_=values, annotation=cls, direction="read")
-        return cls.construct(_fields_set, **dealiased_object)
-
-    @classmethod
-    def construct(
-        cls: typing.Type["Model"], _fields_set: typing.Optional[typing.Set[str]] = None, **values: typing.Any
-    ) -> "Model":
-        dealiased_object = convert_and_respect_annotation_metadata(object_=values, annotation=cls, direction="read")
-        return super().construct(_fields_set, **dealiased_object)
+        # Allow fields begining with `model_` to be used in the model
+        protected_namespaces = ()
 
     def json(self, **kwargs: typing.Any) -> str:
         kwargs_with_defaults: typing.Any = {
@@ -106,9 +103,7 @@ def dict(self, **kwargs: typing.Any) -> typing.Dict[str, typing.Any]:
             **kwargs,
         }
 
-        dict_dump = super().dict(**kwargs_with_defaults_exclude_unset_include_fields)
-
-        return convert_and_respect_annotation_metadata(object_=dict_dump, annotation=self.__class__, direction="write")
+        return super().dict(**kwargs_with_defaults_exclude_unset_include_fields)
 
 
 def _union_list_of_pydantic_dicts(
@@ -173,14 +168,14 @@ def universal_root_validator(
     pre: bool = False,
 ) -> typing.Callable[[AnyCallable], AnyCallable]:
     def decorator(func: AnyCallable) -> AnyCallable:
-        return pydantic.root_validator(pre=pre)(func)  # type: ignore # Pydantic v1
+        return pydantic.v1.root_validator(pre=pre)(func)  # type: ignore # Pydantic v1
 
     return decorator
 
 
 def universal_field_validator(field_name: str, pre: bool = False) -> typing.Callable[[AnyCallable], AnyCallable]:
     def decorator(func: AnyCallable) -> AnyCallable:
-        return pydantic.validator(field_name, pre=pre)(func)  # type: ignore # Pydantic v1
+        return pydantic.v1.validator(field_name, pre=pre)(func)  # type: ignore # Pydantic v1
 
     return decorator
 

generators/python/fastapi/versions.yml

@@ -1,4 +1,11 @@
 # For unreleased changes, use unreleased.yml
+- version: 1.6.1
+  irVersion: 53
+  changelogEntry:
+    - type: fix
+      summary: | 
+        Update `pydantic_utilities.py` to handle `__slots__` in v2 on v1 mode. 
+
 - version: 1.6.0
   irVersion: 53
   changelogEntry: