File download responses in FastAPI - Mini Project: Build & Apply

File Download Responses with FastAPI

📖 Scenario: You are building a simple web API that allows users to download files from your server. This is useful for sharing documents, images, or any files through a web application.

🎯 Goal: Create a FastAPI app that serves a file download response when a user visits a specific URL.

📋 What You'll Learn

Create a FastAPI app instance named app

Create a file path variable named file_path with the exact value "./sample.txt"

Create a route /download that returns the file as a download response

Use FastAPI's FileResponse to send the file with the filename "downloaded_sample.txt"

💡 Why This Matters

🌍 Real World

Many web applications need to provide files for users to download, such as reports, images, or documents.

💼 Career

Understanding how to serve files securely and correctly is important for backend developers working with web APIs.

1

Create FastAPI app and file path

Import FastAPI from fastapi and create an app instance called app. Then create a variable called file_path and set it to the string "./sample.txt".

FastAPI

from fastapi import FastAPI

# Create FastAPI app instance
# Your code here

Need a hint?

Use app = FastAPI() to create the app instance.

2

Import FileResponse for file downloads

Import FileResponse from fastapi.responses to prepare for sending files as responses.

FastAPI

from fastapi import FastAPI
from fastapi.responses import FileResponse

app = FastAPI()
file_path = "./sample.txt"
# Your code here

Need a hint?

Use from fastapi.responses import FileResponse.

3

Create download route returning FileResponse

Create a route /download using @app.get("/download"). Define a function called download_file that returns a FileResponse with the path set to file_path and the filename set to "downloaded_sample.txt".

FastAPI

from fastapi import FastAPI
from fastapi.responses import FileResponse

app = FastAPI()
file_path = "./sample.txt"

# Create /download route
# Your code here

Need a hint?

Use @app.get("/download") and return FileResponse(path=file_path, filename="downloaded_sample.txt").

4

Add media_type for correct file type

Modify the FileResponse in the download_file function to include media_type="application/octet-stream" so the browser treats it as a file download.

FastAPI

from fastapi import FastAPI
from fastapi.responses import FileResponse

app = FastAPI()
file_path = "./sample.txt"

@app.get("/download")
def download_file():
    # Add media_type to FileResponse
    # Your code here

Need a hint?

Add media_type="application/octet-stream" inside FileResponse().