EmerikoandClaude Opus 4.8
6abc9f0acc
The ponytail API example returned the raw ORM model, which exposes every column. Restore a response_model whitelist (the trust boundary) while still cutting the repository/service/exception ceremony. Matches the skill's own 'never cut security' rule. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
69 lines
2.2 KiB
Markdown
69 lines
2.2 KiB
Markdown
# API Endpoint
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**Task:** "Add an endpoint that returns a user by id."
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## Without Ponytail
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```
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app/
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├── controllers/user_controller.py
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├── services/user_service.py
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├── repositories/user_repository.py
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├── schemas/user_schemas.py
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└── exceptions/user_exceptions.py
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```
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```python
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# schemas/user_schemas.py
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class UserResponseDTO(BaseModel):
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id: int
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name: str
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email: str
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# repositories/user_repository.py
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class UserRepository:
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def __init__(self, db: Session):
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self.db = db
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def find_by_id(self, user_id: int) -> User | None:
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return self.db.get(User, user_id)
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# services/user_service.py
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class UserService:
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def __init__(self, repo: UserRepository):
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self.repo = repo
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def get_user(self, user_id: int) -> User:
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user = self.repo.find_by_id(user_id)
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if user is None:
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raise UserNotFoundError(user_id)
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return user
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# controllers/user_controller.py
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@router.get("/users/{user_id}", response_model=UserResponseDTO)
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def get_user(user_id: int, service: UserService = Depends(get_user_service)):
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try:
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return service.get_user(user_id)
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except UserNotFoundError:
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raise HTTPException(status_code=404, detail="User not found")
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```
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Five files, three classes, a custom exception, and a dependency-injection chain — wrapping one database call.
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## With Ponytail
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```python
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# ponytail: drop the layers; keep the response schema, it whitelists what leaves the API
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class UserOut(BaseModel):
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id: int
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name: str
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email: str
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@app.get("/users/{user_id}", response_model=UserOut)
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def get_user(user_id: int, db: Session = Depends(get_db)):
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user = db.get(User, user_id)
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if not user:
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raise HTTPException(404)
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return user
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```
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**5 files → 9 lines.** The repository, service, and custom exception were ceremony. The response schema was not: it whitelists which fields leave the API, so it stays. Returning the raw ORM model (`return user`) would leak every column, including the ones you never meant to expose. That is the line ponytail draws, and it is the same one the skill draws in "when NOT to be lazy": cut the layers, keep the trust boundary. Add a service layer when a second caller shows up, if it ever does.
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