FastAPI File Upload Example

This project demonstrates how to upload files using FastAPI, save them on the server, and store metadata in a SQLite database. The application also allows retrieving the uploaded files through a specific endpoint.

Features

• Upload multiple files (images in this example) along with product details (name and price).
• Store metadata about the uploaded files and products in a SQLite database.
• Retrieve uploaded files using their filenames.

---

How It Works

File Upload Directory

The uploaded files are saved in the ./uploaded_files directory. If the directory does not exist, it is created automatically when the application starts.

Database

The application uses SQLite for storing data. It includes two tables:

1. products: Stores product details (id, name, price).
2. images: Stores metadata about uploaded images (id, filename, product_id).

Endpoints

1. Create Product ( POST /products/ )

• Accepts product details (name and price) as form data and a list of files for upload.
• Saves the files (images in this example) to the server and stores their metadata in the database.
• Returns the product details along with URLs to access the uploaded files.

2. Retrieve File ( GET /files/{filename} )

• Fetches the file by its filename and returns it as a response.
• Guesses the file's media type based on its extension.
• Returns a 404 error if the file does not exist.

---

Setup

Using pip

1. Install Dependencies

Make sure you have Python installed. Then, install the required dependencies:

pip install fastapi uvicorn sqlalchemy pydantic

2. Run the Application

Start the FastAPI application with the following command:

uvicorn app.main:app --reload

Using uv

1. Install Dependencies and run the application

uv run uvicorn app.main:app --reload

The application will be available at http://localhost:8000.

Usage

1. Test with Swagger UI

Navigate to http://localhost:8000/docs to access the interactive API documentation. Use the Swagger UI to test the endpoints.

2. Example curl Usage

You can also use curl to test the POST /products/ endpoint. Here's an example:

curl -X 'POST' \
  'http://localhost:8000/products/?name=Apple&price=4.99' \
  -H 'accept: application/json' \
  -H 'Content-Type: multipart/form-data' \
  -F 'files=@/full/path/to/image1.png;type=image/png' \
  -F 'files=@/full/path/to/image2.png;type=image/png'

Replace /full/path/to/image1.png and /full/path/to/image2.png with the actual paths to the files you want to upload.

3. Retrieve Uploaded Files

To retrieve a file, use the GET /files/{filename} endpoint. For example:

curl -X 'GET' 'http://localhost:8000/files/image1.png' --output image1.png

This will download the file named image1.png to the current directory.

---

Project Structure

.
├── app/
│   └── main.py            # Main application code
├── uploaded_files/        # Directory to store uploaded files (created automatically)
└── test.db                # SQLite database file (created automatically)

---

Notes

• Ensure that the filenames of uploaded files are unique to avoid overwriting existing files.
• The server attempts to guess the media type of the uploaded files using their extensions and serves them accordingly. If the type cannot be determined, it defaults to application/octet-stream.
• Modify the code if your use case involves more complex validation or additional file handling logic.