feat, python: allow extra fields not specified in model to come throu…

…gh (#3131)

generators/python/sdk/CHANGELOG.md

@@ -5,6 +5,35 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.11.10] - 2024-03-08
+
+- feature: Expose a feature flag to pass through additional properties not specified within your pydantic model from your SDK. This allows for easier forward compatibility should your SDK drift behind your spec.
+
+  Config:
+
+  ```yaml
+  generators:
+    - name: fernapi/fern-python-sdk
+      ...
+      config:
+        pydantic_config:
+          extra_fields: "allow"
+  ```
+
+  Example generated code:
+
+  ```python
+  # my_object.py
+  class MyObject(pydantic.BaseModel):
+      string: typing.Optional[str] = None
+      ...
+
+  # main.py
+  o = pydantic.parse_obj_as(MyObject, {"string": "string", "my_new_property": "custom_value"})
+
+  print(o.my_new_property) # <--- "custom_value"
+  ```
+
 ## [0.11.9] - 2024-03-04
 
 - chore: Use docstrings instead of Pydantic field descriptions. This is meant to be a cleanliness change.

generators/python/sdk/VERSION

@@ -1 +1 @@
-0.11.9
+0.11.10

generators/python/src/fern_python/external_dependencies/pydantic.py

@@ -74,6 +74,10 @@ class Extra:
         def forbid(version: PydanticVersionCompatibility) -> AST.Expression:
             return AST.Expression(_export(version, "Extra", "forbid"))
 
+        @staticmethod
+        def allow(version: PydanticVersionCompatibility) -> AST.Expression:
+            return AST.Expression(_export(version, "Extra", "allow"))
+
     @staticmethod
     def root_validator(version: PydanticVersionCompatibility, pre: bool = False) -> AST.FunctionInvocation:
         return AST.FunctionInvocation(

generators/python/src/fern_python/generators/fastapi/fastapi_generator.py

@@ -55,6 +55,7 @@ def run(
         custom_config = FastAPICustomConfig.parse_obj(generator_config.custom_config or {})
         self._pydantic_model_custom_config = PydanticModelCustomConfig(
             forbid_extra_fields=True,
+            extra_fields="forbid",
             wrapped_aliases=True,
             include_union_utils=True,
             include_validators=custom_config.include_validators,

generators/python/src/fern_python/generators/pydantic_model/custom_config.py

@@ -1,3 +1,5 @@
+from typing import Literal, Optional
+
 import pydantic
 
 from ...external_dependencies.pydantic import PydanticVersionCompatibility
@@ -13,7 +15,9 @@ class BasePydanticModelCustomConfig(pydantic.BaseModel):
 
 class PydanticModelCustomConfig(BasePydanticModelCustomConfig):
     include_validators: bool = False
+    # DEPRECATED: use `extra_fields` instead
     forbid_extra_fields: bool = False
+    extra_fields: Optional[Literal["allow", "forbid"]] = "allow"
     wrapped_aliases: bool = False
     skip_formatting: bool = False
     include_union_utils: bool = False

generators/python/src/fern_python/generators/pydantic_model/fern_aware_pydantic_model.py

@@ -61,7 +61,7 @@ def __init__(
             else None,
             docstring=docstring,
             snippet=snippet,
-            forbid_extra_fields=custom_config.forbid_extra_fields,
+            extra_fields="forbid" if custom_config.forbid_extra_fields else custom_config.extra_fields,
             frozen=custom_config.frozen,
             orm_mode=custom_config.orm_mode,
             smart_union=custom_config.smart_union,

generators/python/src/fern_python/pydantic_codegen/pydantic_model.py

@@ -2,7 +2,7 @@
 
 import dataclasses
 from types import TracebackType
-from typing import Iterable, List, Optional, Sequence, Tuple, Type, Union
+from typing import Iterable, List, Literal, Optional, Sequence, Tuple, Type, Union
 
 from fern_python.codegen import AST, ClassParent, LocalClassReference, SourceFile
 from fern_python.external_dependencies import Pydantic, PydanticVersionCompatibility
@@ -33,7 +33,7 @@ def __init__(
         parent: ClassParent = None,
         docstring: Optional[str] = None,
         snippet: Optional[str] = None,
-        forbid_extra_fields: bool = False,
+        extra_fields: Optional[Literal["allow", "forbid"]] = None,
     ):
         self._source_file = source_file
         self._class_declaration = AST.ClassDeclaration(
@@ -50,7 +50,7 @@ def __init__(
         self._version = version
         self._root_type: Optional[AST.TypeHint] = None
         self._fields: List[PydanticField] = []
-        self._forbid_extra_fields = forbid_extra_fields
+        self._extra_fields = extra_fields
         self._frozen = frozen
         self._orm_mode = orm_mode
         self._smart_union = smart_union
@@ -306,13 +306,20 @@ def _add_config_class(self) -> None:
                 )
             )
 
-        if self._forbid_extra_fields:
+        if self._extra_fields == "forbid":
             config.add_class_var(
                 AST.VariableDeclaration(
                     name="extra",
                     initializer=Pydantic.Extra.forbid(self._version),
                 )
             )
+        elif self._extra_fields == "allow":
+            config.add_class_var(
+                AST.VariableDeclaration(
+                    name="extra",
+                    initializer=Pydantic.Extra.allow(self._version),
+                )
+            )
 
         if len(self.json_encoders) > 0:
             config.add_class_var(