backend-fastapi-python

Name: backend-fastapi-python
Author: avibebuilder

109stars17forks

How to install backend-fastapi-python?

avibebuilder/claude-prime/backend-fastapi-python

$npx -y skills add avibebuilder/claude-prime --skill backend-fastapi-python

Installs into the current project.

Summary

Use this skill for any Python backend work in this project: building FastAPI endpoints, writing service functions, defining Pydantic/SQLModel schemas, running Alembic migrations, or debugging 422 errors. Essential for authentication and authorization patterns — setting up get_cur

Files · 1

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SKILL.md

1	# Backend FastAPI Python
2
3	Project-specific conventions for FastAPI with SQLModel, pydantic-settings, and async SQLAlchemy.
4
5	## Architecture Decisions
6
7	1. Services are stateless functions — Not classes. First param is `db: AsyncSession`.
8	2. Generic response wrapper — Always use `ApiResponse[T]` for consistency.
9	3. Dependencies chain — `get_current_user` -> `require_auth` -> `require_admin`.
10	4. Module-scoped config — Each module can have its own `{module}_config.py`.
11	5. Error codes for frontend — `AppException(status, message, error_code)`.
12
13	## Gotchas
14
15	- SQLModel `Relationship()` fields are NOT included in API responses by default. You must explicitly add them to `model_config` or use a separate response schema with those fields.
16	- `AsyncSession.refresh()` does not load relationships. After commit, re-query with `.options(selectinload(...))` if you need related objects.
17	- Pydantic V2 uses `model_validator` not `validator`. The `@validator` decorator is V1 and will break silently or raise deprecation warnings.
18	- `Depends()` in FastAPI creates a NEW instance per request — don't store state in dependency return values expecting it to persist.
19	- Background tasks (`BackgroundTasks`) run AFTER the response is sent. If they fail, the client already got a 200. Use proper task queues (Celery, ARQ) for anything that must not silently fail.
20	- Alembic `--autogenerate` misses: table renames (generates drop+create), index changes on existing columns, and `Enum` type modifications in PostgreSQL. Always review generated migrations.
21	- `async def` endpoints block the event loop if you call sync I/O inside them. Use `run_in_executor` for sync libraries or define the endpoint as `def` (FastAPI runs sync endpoints in a threadpool).
22	- `HTTPException` from FastAPI and `HTTPException` from Starlette are different classes. Importing the wrong one causes middleware to miss exception handlers.
23	- SQLAlchemy's `lazy="selectin"` on relationships causes N+1 queries in async sessions. Use explicit `selectinload()` in queries instead.
24	- `Optional[str] = None` in query params makes the field optional. `str = None` also works but loses type information — prefer the explicit `Optional` form.
25	- When using `response_model`, FastAPI filters OUT any fields not in the model. If your response is missing data, check that the response model includes all fields, not just the ORM model.
26
27	## References
28
29	\| When you need... \| Read \|
30	\|------------------\|------\|
31	\| Directory layout \| [file-structure.md](./references/file-structure.md) \|
32	\| Settings and env vars \| [configuration.md](./references/configuration.md) \|
33	\| Database sessions and connections \| [database.md](./references/database.md) \|
34	\| ORM models \| [models.md](./references/models.md) \|
35	\| Request/response schemas \| [schemas.md](./references/schemas.md) \|
36	\| Router and endpoint patterns \| [routing.md](./references/routing.md) \|
37	\| Service layer patterns \| [services.md](./references/services.md) \|
38	\| Dependency injection \| [dependencies.md](./references/dependencies.md) \|
39	\| Middleware setup \| [middleware.md](./references/middleware.md) \|
40	\| Error handling \| [error-handling.md](./references/error-handling.md) \|
41	\| Auth flow example \| [auth.md](./references/auth.md) \|

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backend-fastapi-python

109stars17forks

View on GitHub

How to install backend-fastapi-python?

avibebuilder/claude-prime/backend-fastapi-python

$npx -y skills add avibebuilder/claude-prime --skill backend-fastapi-python

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Backend FastAPI Python
2
3	Project-specific conventions for FastAPI with SQLModel, pydantic-settings, and async SQLAlchemy.
4
5	## Architecture Decisions
6
7	1. Services are stateless functions — Not classes. First param is `db: AsyncSession`.
8	2. Generic response wrapper — Always use `ApiResponse[T]` for consistency.
9	3. Dependencies chain — `get_current_user` -> `require_auth` -> `require_admin`.
10	4. Module-scoped config — Each module can have its own `{module}_config.py`.
11	5. Error codes for frontend — `AppException(status, message, error_code)`.
12
13	## Gotchas
14
15	- SQLModel `Relationship()` fields are NOT included in API responses by default. You must explicitly add them to `model_config` or use a separate response schema with those fields.
16	- `AsyncSession.refresh()` does not load relationships. After commit, re-query with `.options(selectinload(...))` if you need related objects.
17	- Pydantic V2 uses `model_validator` not `validator`. The `@validator` decorator is V1 and will break silently or raise deprecation warnings.
18	- `Depends()` in FastAPI creates a NEW instance per request — don't store state in dependency return values expecting it to persist.
19	- Background tasks (`BackgroundTasks`) run AFTER the response is sent. If they fail, the client already got a 200. Use proper task queues (Celery, ARQ) for anything that must not silently fail.
20	- Alembic `--autogenerate` misses: table renames (generates drop+create), index changes on existing columns, and `Enum` type modifications in PostgreSQL. Always review generated migrations.
21	- `async def` endpoints block the event loop if you call sync I/O inside them. Use `run_in_executor` for sync libraries or define the endpoint as `def` (FastAPI runs sync endpoints in a threadpool).
22	- `HTTPException` from FastAPI and `HTTPException` from Starlette are different classes. Importing the wrong one causes middleware to miss exception handlers.
23	- SQLAlchemy's `lazy="selectin"` on relationships causes N+1 queries in async sessions. Use explicit `selectinload()` in queries instead.
24	- `Optional[str] = None` in query params makes the field optional. `str = None` also works but loses type information — prefer the explicit `Optional` form.
25	- When using `response_model`, FastAPI filters OUT any fields not in the model. If your response is missing data, check that the response model includes all fields, not just the ORM model.
26
27	## References
28
29	\| When you need... \| Read \|
30	\|------------------\|------\|
31	\| Directory layout \| [file-structure.md](./references/file-structure.md) \|
32	\| Settings and env vars \| [configuration.md](./references/configuration.md) \|
33	\| Database sessions and connections \| [database.md](./references/database.md) \|
34	\| ORM models \| [models.md](./references/models.md) \|
35	\| Request/response schemas \| [schemas.md](./references/schemas.md) \|
36	\| Router and endpoint patterns \| [routing.md](./references/routing.md) \|
37	\| Service layer patterns \| [services.md](./references/services.md) \|
38	\| Dependency injection \| [dependencies.md](./references/dependencies.md) \|
39	\| Middleware setup \| [middleware.md](./references/middleware.md) \|
40	\| Error handling \| [error-handling.md](./references/error-handling.md) \|
41	\| Auth flow example \| [auth.md](./references/auth.md) \|

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Type