[Python] How can I stream a large CSV download in Flask without loading the whole file into...

I have an endpoint that exports the report as a CSV.

import io, csv
from flask import Flask, Response

app = Flask(__name__)

def get_report_rows():
# imagine 5 million DB rows here
for i in range(5_000_000):
yield (i, f"name-{i}", i % 100)

@app.get("/export")
def export():
rows = get_report_rows()

output = io.StringIO()
writer = csv.writer(output)
writer.writerow(["id", "name", "score"])
writer.writerows(rows)
output.seek(0)

return Response(
output.getvalue(),
mimetype="text/csv",
headers={"Content-Disposition": "attachment; filename=report.csv"}
)



For large datasets, this endpoint crashes. How can I create the endpoint such that I can stream a CSV row by row?

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