René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`oneOf` inside `allOf` is ignored during code generation","articleBody":"**Describe the bug**\n\nWhen using `allOf` with a nested `oneOf`, the code generator only processes the first schema in the `allOf` list and ignores the `oneOf` portion. Fields defined in the `oneOf` schemas are not included as typed attributes in the generated class, but instead end up in `additional_properties` as untyped data.\n\n**OpenAPI Spec File**\n\n\u003cdetails\u003e\n\u003csummary\u003eClick to expand full OpenAPI spec\u003c/summary\u003e\n\n```yaml\nopenapi: 3.0.3\ninfo:\n  title: AllOf + OneOf Test\n  version: 1.0.0\npaths:\n  /animals/{animal_id}:\n    get:\n      operationId: get_animal\n      parameters:\n        - name: animal_id\n          in: path\n          required: true\n          schema:\n            type: string\n      responses:\n        '200':\n          description: Success\n          content:\n            application/json:\n              schema:\n                $ref: '#/components/schemas/Animal'\n\ncomponents:\n  schemas:\n    Animal:\n      type: object\n      required:\n        - id\n        - attributes\n      properties:\n        id:\n          type: string\n        attributes:\n          allOf:\n            - $ref: '#/components/schemas/CommonAttributes'\n            - oneOf:\n                - $ref: '#/components/schemas/DogAttributes'\n                - $ref: '#/components/schemas/CatAttributes'\n\n    CommonAttributes:\n      type: object\n      properties:\n        name:\n          type: string\n          description: Animal's name\n        age:\n          type: integer\n          description: Animal's age in years\n\n    DogAttributes:\n      type: object\n      properties:\n        breed:\n          type: string\n          description: Dog breed\n        is_good_boy:\n          type: boolean\n          description: Is this a good boy?\n\n    CatAttributes:\n      type: object\n      properties:\n        color:\n          type: string\n          description: Cat fur color\n        lives_remaining:\n          type: integer\n          description: Number of lives remaining (out of 9)\n```\n\n\u003c/details\u003e\n\nKey part of the spec (the problematic schema):\n```yaml\nattributes:\n  allOf:\n    - $ref: '#/components/schemas/CommonAttributes'  # name, age\n    - oneOf:\n        - $ref: '#/components/schemas/DogAttributes'   # breed, is_good_boy\n        - $ref: '#/components/schemas/CatAttributes'   # color, lives_remaining\n```\n\n**Generated Code**\n\nThe generated `AnimalAttributes` class only includes fields from `CommonAttributes`:\n\n```python\n@_attrs_define\nclass AnimalAttributes:\n    \"\"\"\n    Attributes:\n        name (Union[Unset, str]): Animal's name\n        age (Union[Unset, int]): Animal's age in years\n    \"\"\"\n\n    name: Union[Unset, str] = UNSET\n    age: Union[Unset, int] = UNSET\n    additional_properties: dict[str, Any] = _attrs_field(init=False, factory=dict)\n```\n\n\u003cdetails\u003e\n\u003csummary\u003eClick to expand full generated file\u003c/summary\u003e\n\n```python\nfrom typing import Any, TypeVar, Union\n\nfrom attrs import define as _attrs_define\nfrom attrs import field as _attrs_field\n\nfrom ..types import UNSET, Unset\n\nT = TypeVar(\"T\", bound=\"AnimalAttributes\")\n\n\n@_attrs_define\nclass AnimalAttributes:\n    \"\"\"\n    Attributes:\n        name (Union[Unset, str]): Animal's name\n        age (Union[Unset, int]): Animal's age in years\n    \"\"\"\n\n    name: Union[Unset, str] = UNSET\n    age: Union[Unset, int] = UNSET\n    additional_properties: dict[str, Any] = _attrs_field(init=False, factory=dict)\n\n    def to_dict(self) -\u003e dict[str, Any]:\n        name = self.name\n\n        age = self.age\n\n        field_dict: dict[str, Any] = {}\n        field_dict.update(self.additional_properties)\n        field_dict.update({})\n        if name is not UNSET:\n            field_dict[\"name\"] = name\n        if age is not UNSET:\n            field_dict[\"age\"] = age\n\n        return field_dict\n\n    @classmethod\n    def from_dict(cls: type[T], src_dict: dict[str, Any]) -\u003e T:\n        d = src_dict.copy()\n        name = d.pop(\"name\", UNSET)\n\n        age = d.pop(\"age\", UNSET)\n\n        animal_attributes = cls(\n            name=name,\n            age=age,\n        )\n\n        animal_attributes.additional_properties = d\n        return animal_attributes\n\n    @property\n    def additional_keys(self) -\u003e list[str]:\n        return list(self.additional_properties.keys())\n\n    def __getitem__(self, key: str) -\u003e Any:\n        return self.additional_properties[key]\n\n    def __setitem__(self, key: str, value: Any) -\u003e None:\n        self.additional_properties[key] = value\n\n    def __delitem__(self, key: str) -\u003e None:\n        del self.additional_properties[key]\n\n    def __contains__(self, key: str) -\u003e bool:\n        return key in self.additional_properties\n```\n\n\u003c/details\u003e\n\nFields from `DogAttributes` and `CatAttributes` are not present as typed attributes. When parsing JSON responses containing these fields (e.g., `breed`, `is_good_boy`), they end up in `additional_properties` as untyped data.\n\n**Expected Behavior**\n\nSince `oneOf` means \"exactly one of\", the generator should create separate classes for each variant and use a Union type:\n\n```python\n@_attrs_define\nclass AnimalAttributesWithDog:\n    \"\"\"CommonAttributes + DogAttributes\"\"\"\n    name: Union[Unset, str] = UNSET\n    age: Union[Unset, int] = UNSET\n    breed: Union[Unset, str] = UNSET\n    is_good_boy: Union[Unset, bool] = UNSET\n\n@_attrs_define\nclass AnimalAttributesWithCat:\n    \"\"\"CommonAttributes + CatAttributes\"\"\"\n    name: Union[Unset, str] = UNSET\n    age: Union[Unset, int] = UNSET\n    color: Union[Unset, str] = UNSET\n    lives_remaining: Union[Unset, int] = UNSET\n\n# The actual type used in Animal\nAnimalAttributes = Union[AnimalAttributesWithDog, AnimalAttributesWithCat]\n```\n\n**Desktop (please complete the following information):**\n - OS: Linux (Ubuntu 22.04)\n - Python Version: 3.13.5\n - openapi-python-client version: 0.25.3\n\n**Additional context**\n\nCurrent workaround requires accessing fields via `additional_properties`, which loses type safety:\n```python\nanimal.additional_properties.get('breed')  # type is Any, not str\n```\n\nNote that `DogAttributes` and `CatAttributes` are generated as separate model files, but they are not merged into the `AnimalAttributes` class as expected from the `allOf` + `oneOf` combination.\n","author":{"url":"https://github.com/tsuga","@type":"Person","name":"tsuga"},"datePublished":"2025-10-06T11:40:01.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/1328/openapi-python-client/issues/1328"}