FastAPI Chat Completion Template

A modern, modular FastAPI template for building chat completion APIs using LangChain and Anthropic's Claude.

Features

• FastAPI-based REST API
• LangChain integration with Anthropic's Claude
• Modular service architecture
• Async support
• Conversation history management
• Environment-based configuration
• Type hints and validation

Prerequisites

• Python 3.8+
• Anthropic API key

Installation

1. Clone the repository:

git clone https://github.com/yourusername/fastAPI-chat-completion-template.git
cd fastAPI-chat-completion-template

2. Create and activate a virtual environment:

python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate

3. Install dependencies:

pip install -r requirements.txt

4. Set up environment variables:

cp .env.EXAMPLE .env
# Edit .env with your Anthropic API key

Project Structure

.
├── api/
│   └── routes/
│       └── chat_routes.py    # API endpoints
├── models/
│   └── chat.py              # Pydantic models
├── services/
│   ├── base.py              # Base service class
│   └── chat/
│       ├── base.py          # Base chat service
│       └── anthropic.py     # Anthropic implementation
├── main.py                  # Application entry point
├── requirements.txt         # Project dependencies
└── .env                     # Environment variables

Usage

1. Start the server:

python -m uvicorn main:app --reload

2. Access the API documentation:

• Swagger UI: http://localhost:8001/docs
• ReDoc: http://localhost:8001/redoc

API Endpoints

Chat Completion

• POST /api/chat/completions

  {
    "message": {
      "content": "Your message here",
      "role": "user" // optional, defaults to "user"
    }
  }

Chat History

• GET /api/chat/history - Get conversation history
• DELETE /api/chat/history - Clear conversation history

Development

Adding New Chat Providers

1. Create a new service class in services/chat/
2. Inherit from BaseChatService
3. Implement the get_chat_response method
4. Update the service factory in api/routes/chat_routes.py

Running Tests

pytest

Contributing

1. Fork the repository
2. Create a feature branch
3. Commit your changes
4. Push to the branch
5. Create a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• FastAPI
• LangChain
• Anthropic