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Upload a StringIO object with send_file

Posted by Stephane Wirtel on 2010-07-07 @ 21:57 and filed in Utilities

Sometimes, you want to avoid the creation of a file to send this file to the client.

So, in this case, you can use a StringIO object with the send_file helper.

Here is an example:

#!/usr/bin/env python

# Thanks to Dan Jacob for a part of the code !

from flask import Flask, send_file
import StringIO

app = Flask(__name__)

def index():
    strIO = StringIO.StringIO()
    strIO.write('Hello from Dan Jacob and Stephane Wirtel !')
    return send_file(strIO,

This snippet by Stephane Wirtel can be used freely for anything you like. Consider it public domain.