Python Flask send_file StringIO blank files

Question

I\'m using python 3.5 and flask 0.10.1 and liking it, but having a bit of trouble with send_file. I ultimately want to process a pandas dataframe (from Form data, which is u

Answer 1

I guess you should write bytes.

from io import BytesIO    

from flask import Flask, send_file


app = Flask(__name__)


@app.route('/test_download', methods=['POST'])
def test_download():
    # Use BytesIO instead of StringIO here.
    buffer = BytesIO()
    buffer.write(b'jJust some letters.')
    # Or you can encode it to bytes.
    # buffer.write('Just some letters.'.encode('utf-8'))
    buffer.seek(0)
    return send_file(buffer, as_attachment=True,
                     attachment_filename='a_file.txt',
                     mimetype='text/csv')


if __name__ == '__main__':
    app.run(debug=True)