FastAPI File Server

This is a simple FastAPI application that provides APIs for creating and serving files. The application allows you to create a file with a unique ID and download it. After the file is served for download, it is automatically deleted from the server.

How It Works

Directory Setup

The application uses a directory named files to store the files temporarily. If the directory does not already exist, it is created automatically when the application starts.

Endpoints

1. POST /create-file/

This endpoint is used to create a new file with a unique ID.

• Description:

  • A unique file ID is generated using uuid.
  • A text file is created in the files directory with the content:
    This is a test file. with file id <file_id>.
  • The file ID is returned in the response.

• Response:

  • A JSON object containing the unique file_id.

• Example Response:

  {
      "file_id": "123e4567-e89b-12d3-a456-426614174000"
  }

2. GET /fileserver/{file_id}

This endpoint is used to download a file by its unique ID.

• Description:

  • The application looks for a file with the name <file_id>.txt in the files directory.
  • If the file exists, it is served as a downloadable attachment.
  • After serving the file, it is deleted from the files directory.
  • If the file does not exist, the application returns a 404 File Not Found error.

• Response:

  • If the file exists, the file is served as an attachment for download.
  • If the file does not exist, a 404 error is returned.

• Example Response for Success:

  • The file is downloaded as <file_id>.txt.

• Example Response for Failure:

  {
      "detail": "File not found"
  }

Code Walkthrough

BASE_DIR

• The variable BASE_DIR is a Path object representing the files directory.
• The directory is created automatically using the mkdir(exist_ok=True) method.

POST /create-file/

• A unique file ID is generated using uuid.uuid4.
• A file is created in the BASE_DIR directory with the name <file_id>.txt.
• The content of the file includes the text: This is a test file. with file id <file_id>.

GET /fileserver/{file_id}

• The file path is constructed as BASE_DIR / <file_id>.txt.
• The application checks if the file exists using file_path.exists() and file_path.is_file().
• If the file exists, it is served as a FileResponse with the appropriate headers for downloading.
• After the file is served, the unlink() method is called to delete the file.
• If an error occurs during deletion, it is logged but does not interrupt the response.

Running the Application

1. Install FastAPI and Uvicorn:

   pip install fastapi uvicorn

2. Start the FastAPI server:

   uvicorn main:app --reload

3. Access the API documentation at http://127.0.0.1:8000/docs.

Example Usage

Create a File

1. Send a POST request to /create-file/.
2. Copy the file_id from the response.

Download a File

1. Send a GET request to /fileserver/{file_id}, replacing {file_id} with the unique file ID.
2. The file will be downloaded and automatically deleted from the server.

Notes

• Ensure the application has write permissions to the files directory.
• Files are deleted automatically after being served for download. If the file is not downloaded, it will remain in the files directory.