Flask return csv from sql

from flask import Response, send_file
    try:
        from cStringIO import StringIO                                                         
    except ImportError:
        from StringIO import StringIO

    output = StringIO()

    # 查詢
    results = Users.query.all()

    # 寫入 csv file
    for user in results:
    output.write("%s,%s,%s\n" % (user.id, user.name, user.email))

    # 輸出
    filename = address.csv

    response = Response(output.getvalue(), mimetype='text/csv')
    response.headers['Content-Disposition'] = 'attachment; filename=' + filename

    output.seek(0)
    return send_file(output, as_attachment=True, attachment_filename=filename)

References :
flask note - 我的Java生活 - ITeye技术网站
Returning MySQL query data in a csv file with Flask