Favorite property / product with session / cookies using php

If you do not want to use a database, you will need to save it to another location that allows future queries such as files or cookies.

The risk of saving on cookies is that they are transferred on all HTTP requests. In other words, if you save a lot of data in cookies, the HTTP header will be large and the requests will be slow.

The ideal would be to save only a user identifier in the cookie and keep the real estate IDs on the server, either in database or in files