[Python] How to Download a File after POSTing data using FastAPI?

I am creating a web application that receives some text, converts the text into speech, and returns an mp3 file, which is saved to a temporary directory.

I want to be able to download the file from the html page (i.e., the frontend), but I don't know how to do that properly.

I know with Flask you can do this:

from app import app
from flask import Flask, send_file, render_template

@app.route('/')
def upload_form():
return render_template('download.html')

@app.route('/download')
def download_file():
path = "html2pdf.pdf"

return send_file(path, as_attachment=True)

if __name__ == "__main__":
app.run()


HTML Example:

<!doctype html>
<title>Python Flask File Download Example</title>
<h2>Download a file</h2>
<p><a href="{{ url_for('.download_file') }}">Download</a></p>


So how do I replicate this with FastAPI?

FastAPI Code:

from fastapi import FastAPI, File, Request, Response, UploadFile
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse, HTMLResponse, StreamingResponse
from fastapi.templating import Jinja2Templates
from gtts import gTTS

templates = Jinja2Templates(directory="templates")


def text_to_speech(language:str, text: str) -> str:
tts = gTTS(text=text, lang=language, slow=False)
tts.save("./temp/welcome.mp3")
#os.system("mpg321 /temp/welcome.mp3")
return "Text to speech conversion successful"


@app.get("/")
def home(request: Request):
return templates.TemplateResponse("index.html", {"request": request})

@app.get("/text2speech")
async def home(request: Request):
if request.method == "POST":
form = await request.form()
if form["message"] and form["language"]:
language = form["language"]
text = form["message"]
translate = text_to_speech(language, text)
path = './temp/welcome.mp3'
value = FileResponse("./temp/welcome.mp3", media_type="audio/mp3")
return value
# return templates.TemplateResponse(
# "index.html",
# {"request": request, "message": text, "language": language, "download": value},
# )



Sample HTML File:

<!doctype html>
<title>Download MP3 File</title>
<h2>Download a file</h2>
<p><a href="{{ url_for('text2speech') }}">Download</a></p>

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