[Python] Redirect to another webpage after background task is complete

I have an endpoint which triggers a process in FastAPI. The process takes several minutes and produces a CSV file that can later be downloaded by the users.

How can I return a message saying that the process is running and redirecting the users to the "Download" page after the process has finished.

So far, I am returning an HTML response pointing to the "Download" page, but if the user clicks on it before the process has finished, they may not get the correct results:

@router.post("/run")
async def run(background_tasks: BackgroundTasks) -> HTMLResponse:
"""
1. Run model.
2. Retrieve output file.
"""

background_tasks.add_task(optimization_process)

content = """
<label for="file">Generating results:</label><br>
<progress id="file" max="100" value="70"> 70% </progress><br>
<body> Visit <a href="./get-results">result page</a> to get the results </body>
"""
return HTMLResponse(content=content)


I am looking to improve this setup by informing the users that the process has started and redirecting them to the next screen after the successful run of optimization_process.

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