Flask wtforms:文件未上传

我正在尝试使用flask_wtforms上传文件。html页面被打开,我可以选择文件,但当我点击提交时,什么也不会发生。没有验证错误或任何其他错误。我试着在文档中搜索支持,但无济于事。以下是代码和相关导入:

路由.py

from werkzeug.utils import secure_filename
import os

@app.route('/upload', methods=['GET', 'POST'])
def upload():
    form = OrderForm()
    if form.validate_on_submit():
        f = form.photo.data
        filename = secure_filename(f.filename)
        f.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        return render_template('upload.html', form=form)
    return render_template('upload.html', form = form)

forms.py

    photo =  FileField('Prescription', validators=[FileRequired(), FileAllowed(['txt', 'jpg', 'jpeg', 'png'], 'Images only!')])
    submit = SubmitField('Place order')

config.py

class Config(object):
    UPLOAD_FOLDER = 'D:\\projects\\project1\project1\\uploads'

编辑1:已添加 upload.html 文件

upload.html

{% block content %}
<form method="POST" enctype="multipart/form-data">
    {{ form.hidden_tag() }}

    <p>
        {{ form.prescription() }}
    </p>
    <p>
        {{ form.submit() }}
    </p>
</form>
{% endblock %}