File download responses in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What FastAPI class is used to send a file as a response for download?

FastAPI uses the <code>FileResponse</code> class to send files as downloadable responses to clients.

beginner

How do you specify the filename that the client will see when downloading a file in FastAPI?

You set the filename parameter in FileResponse. This tells the browser what name to use for the downloaded file.

intermediate

Why is it important to use FileResponse instead of reading the file content and returning it as a string?

Using FileResponse streams the file efficiently without loading it all into memory, which is better for large files and server performance.

intermediate

What HTTP header does FastAPI set automatically when using FileResponse to trigger a file download?

FastAPI sets the Content-Disposition header with attachment; filename="yourfilename" to prompt the browser to download the file.

beginner

Show a simple FastAPI endpoint example that returns a file named 'example.txt' for download.

<pre>from fastapi import FastAPI
from fastapi.responses import FileResponse

app = FastAPI()

@app.get('/download')
async def download_file():
    return FileResponse('example.txt', filename='example.txt')</pre>

Which FastAPI response class is best for sending files to clients for download?

A JSONResponse

B PlainTextResponse

C HTMLResponse

D FileResponse

FileResponse is designed to send files efficiently for download.

What parameter do you use in FileResponse to set the download filename?

A path

B filename

C content

D media_type

The filename parameter sets the name the client sees when downloading.

What HTTP header triggers the browser to download a file instead of displaying it?

A Content-Disposition

B Content-Length

C Cache-Control

D Content-Type

Content-Disposition: attachment tells the browser to download the file.

Why is streaming a file with FileResponse better than reading it fully into memory?

A It avoids loading large files fully into memory

B It is slower

C It uses more memory

D It changes the file content

Streaming avoids high memory use and improves performance for large files.

Which of these is NOT a correct way to send a file for download in FastAPI?

A Using FileResponse with correct path

B Using FileResponse with filename parameter

C Reading file content and returning as string

D Setting Content-Disposition header via FileResponse

Returning file content as string is inefficient and not recommended for downloads.

Explain how to create a FastAPI endpoint that allows users to download a file. Include key steps and parameters.

Think about how the browser knows to download a file and what FastAPI helper you use.

Describe why streaming files with FileResponse is better than reading the whole file into memory before sending.

Consider what happens when a file is very large and how the server handles it.