FastRouter

A simple and intuitive file-based router for FastAPI. This package allows you to define your API routes by structuring your files and directories, making your project more organized and easier to navigate.

Note

You can use this to fuck with your personal or a friends repo but do not push to production :)

🚀 Features

• Static Analysis: Uses tree-sitter to discover routes without executing your code.
• Lazy Loading: Route modules are only imported when the first request hits the endpoint.
• Side-Effect Isolation: Startup is silent. Top-level code in route files only runs on demand.
• Rich OpenAPI Integration:
  • Automatic Summaries: The first line of your docstring becomes the route summary.
  • Detailed Descriptions: The rest of the docstring becomes the route description.
  • Tag Metadata: Configure directory-level documentation with set_tag_metadata.
• Flexible Routing:
  • Static: index.py → /
  • Dynamic: [id].py → /{id}
  • Typed: [id:int].py → /{id:int}
  • Slug: [slug:].py → /{slug}
  • Catch-all: [...path].py → /{path:path}
• Full FastAPI Support: Works with Depends(), Pydantic models, and all HTTP methods.

🛠️ Quick Start

Installation

We recommend using uv for dependency management.

uv add fast-router

Or using pip:

pip install fast-router

Basic Usage

1. Create a routes directory

In your project's root directory, create a folder named routes.

.
├── main.py
└── routes/

2. Define your routes

Create Python files inside the routes directory. For example, to create a "Hello World" endpoint at the root (/), create routes/index.py:

def get():
    """Welcome to FastRouter!"""
    return {"message": "Hello World"}

3. Integrate with FastAPI

In your main.py, use the create_router helper:

import uvicorn
from fast_router import create_router

# Initialize the router
router = create_router("routes")
app = router.get_app()

if __name__ == "__main__":
    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

Running the Server

Run your application using uv:

PYTHONPATH=src uv run main.py

Now visit http://127.0.0.1:8000/ to see your API in action, or http://127.0.0.1:8000/docs for the interactive documentation.

📂 Directory Structure

routes/
├── index.py                 # GET /
├── users/
│   ├── index.py            # GET /users
│   └── [id:int].py        # GET /users/{id}
├── blog/
│   └── [slug:].py         # GET /blog/{slug}
└── files/
    └── [...path].py       # GET /files/{path:path}

📝 Route Handler Example

from fastapi import Query

def get(id: int, q: str = Query(None)):
    """
    Get user by ID.
    
    This description will appear in the expanded section of the 
    OpenAPI documentation, while the first line is the summary.
    """
    return {"user_id": id, "query": q}

⚙️ Advanced Configuration

Tag Metadata

You can customize the documentation for each directory (tag) in your router:

from fast_router import create_router

router = create_router("routes")
router.set_tag_metadata(
    "users", 
    description="Operations with users and their profiles.",
    external_docs={"description": "User Guide", "url": "https://example.com/docs"}
)
app = router.get_app()

Smart Fallback

The router is lazy by default. However, if it detects complex FastAPI features (like Depends() or Pydantic models) that require runtime introspection, it automatically falls back to immediate loading for that specific route to ensure 100% compatibility.

🧪 Running Tests

We use pytest for unit and E2E testing, managed via uv.

make test

📜 License

MIT License