如何从POST请求负载中提取特定信息并保存到txt文件中？

from flask import Flask, request

app = Flask(__name__)

@app.route('/process_post', methods=['POST'])
def process_post():
    # 从POST请求中提取特定信息
    data = request.form.get('key')  # 假设要提取名为'key'的数据

    # 将提取的信息保存到txt文件中
    with open('output.txt', 'w') as file:
        file.write(data)

    return 'Data extracted and saved successfully!'

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

function sendPostRequest() {
    var data = { key: 'value' };  // 要发送的数据，以键值对形式表示

    fetch('/process_post', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(data)
    })
    .then(response => response.text())
    .then(result => {
        console.log(result);  // 输出后端返回的结果
    })
    .catch(error => {
        console.error('Error:', error);
    });
}