Flask-Uploads:如何通过内容(而不仅仅是扩展名)强制文件类型

from flask import Flask
from flask_uploads import UploadSet, configure_uploads, IMAGES

app = Flask(__name__)
photos = UploadSet('photos', IMAGES)

# 配置上传目录和允许的文件类型
app.config['UPLOADED_PHOTOS_DEST'] = 'uploads'
app.config['UPLOADED_PHOTOS_ALLOW'] = IMAGES

configure_uploads(app, photos)

# 自定义回调函数来检查文件内容
def check_file_content(file):
    # 根据文件内容判断文件类型
    # 这里只是一个示例，实际应用中可能需要使用更复杂的逻辑来判断文件类型
    allowed_types = ['image/jpeg', 'image/png']
    if file.content_type not in allowed_types:
        return False
    return True

# 使用file_allowed方法来强制文件类型
photos.file_allowed(check_file_content, 'Invalid file type.')

@app.route('/upload', methods=['POST'])
def upload():
    if 'photo' in request.files:
        filename = photos.save(request.files['photo'])
        return 'File uploaded successfully.'
    return 'No file uploaded.'

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