# Fastapi Router Py

> Create FastAPI routers with CRUD operations, authentication dependencies, and proper response models following established patterns.

- Skill: `microsoft/fastapi-router-py` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add microsoft/fastapi-router-py`
- Raw SKILL.md: https://api.skillmd.com/api/skills/microsoft/fastapi-router-py/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools, DevOps & Infra, API Design
- Tags: Authentication, Crud, Fastapi, Http Status Codes, Pydantic, Python, Router
- License: MIT
- Author: Microsoft (https://skillmd.com/u/microsoft), verified publisher
- Updated: 2026-07-06
- Page: https://skillmd.com/skills/microsoft/fastapi-router-py

---


# FastAPI Router

Create FastAPI routers following established patterns with proper authentication, response models, and HTTP status codes.

## Quick Start

Copy the template from [assets/template.py](assets/template.py) and replace placeholders:
- `{{ResourceName}}` → PascalCase name (e.g., `Project`)
- `{{resource_name}}` → snake_case name (e.g., `project`)
- `{{resource_plural}}` → plural form (e.g., `projects`)

## Authentication Patterns

```python
# Optional auth - returns None if not authenticated
current_user: Optional[User] = Depends(get_current_user)

# Required auth - raises 401 if not authenticated
current_user: User = Depends(get_current_user_required)
```

## Response Models

```python
@router.get("/items/{item_id}", response_model=Item)
async def get_item(item_id: str) -> Item:
    ...

@router.get("/items", response_model=list[Item])
async def list_items() -> list[Item]:
    ...
```

## HTTP Status Codes

```python
@router.post("/items", status_code=status.HTTP_201_CREATED)
@router.delete("/items/{id}", status_code=status.HTTP_204_NO_CONTENT)
```

## Integration Steps

1. Create router in `src/backend/app/routers/`
2. Mount in `src/backend/app/main.py`
3. Create corresponding Pydantic models
4. Create service layer if needed
5. Add frontend API functions

## Best Practices

1. **Pick `def` or `async def` per endpoint based on whether you call async I/O;** do not mix sync and async blocking calls in one handler.
2. **Manage long-lived resources (DB pools, HTTP clients) in `lifespan` and inject via `Depends`;** use `with`/`async with` for per-request resources.