I did the same for caching purpose and stored the response and request data during the controllers
afterAction. You have to define what your requestData should be what values are important for you. Do you only need all GET and POST params or certain headers as well?
Since you have access to the Request object you can collect all the data you need in an array and store it. Keep in mind some requests like a user name/password based login should not be stored. You don’t want to store unencrypted passwords in your db.
What is your current code? I’m not really sure what you miss or what your issue is. Looks like you got everything.