我正在尝试编写一个程序，将图像和延迟上传到服务器，但它没有返回延迟，错误没有找到延迟标头

Question

我是 REST API 的新手，通过遵循教程和文档进行学习我正在尝试构建一个 REST API，它将从我使用 post map 测试我的 API 的计算机上传图像。问题是我也在尝试获取函数的延迟，但它始终提供相同的输出 No latency header found。图片上传工作正常。

到目前为止，我尝试寻找解决方案，如果你们能提供帮助，我将不胜感激，这是我的代码：

import os
from flask import Flask, request, jsonify
from werkzeug.utils import secure_filename
import time

    UPLOAD_FOLDER = 'directory where to save the picture'
    ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])
    
    def allowed_file(filename):
        return '.' in filename and filename.rsplit('.',1)[1].lower() in ALLOWED_EXTENSIONS
    
    app = Flask(__name__)
    app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
    
    @app.route('/media/upload', methods=['POST'])
    def upload_media():
        headers = {`your text`
            'X-QoS-Latency': str(time.time())
        }
        if 'file' not in request.files:
            return jsonify({'error': 'media not provided'}), 400
        file = request.files['file']
        if file.filename == '':
            return jsonify({'error': 'no file selected'}), 400
        if file and allowed_file(file.filename):
            filename = secure_filename(file.filename)
            file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        latency = request.headers.get('X-QoS-Latency')
        if latency:
            latency_ms = round((time.time() - float(latency)) * 1000, 2)
            print(f'Latency: {latency_ms} ms')
        else:
            print('No latency header found.')
        return jsonify({'msg':'media uploaded successfully'}),200, headers
    if __name__== '__main__':
        app.run(debug=True, port=5050)`