Flask send_from_directory（）返回空文件

Question

我正在尝试写入o_filename，以使用户从我的flask Web页面下载它。

if request.method == 'POST':

    # user wants to download from s3

    # user wants to hydrate
    if 'hydrate' in request.files:
        file = request.files['hydrate']
        if file and allowed_hydrate_file(file.filename):

            filename = secure_filename(file.filename)
            file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))

            o_filename = filename
            o_filename = o_filename[:-3]
            o_filename += "jsonl"

            fileWrite = open(o_filename,"w")

            fileWrite.write("reddit")


            print("here")

            file.save(os.path.join(app.config['UPLOAD_FOLDER'], o_filename))

            return send_from_directory(app.config['UPLOAD_FOLDER'],
                           o_filename, as_attachment=True)

现在，用户应该可以下载带有文本“ reddit”的o_fileanme。该代码使用户可以下载o_filename，但是该文件为空。我知道这不是正确的jsonl格式，但是我正在测试。我在做什么错，为什么文件为空？