What would be the best way to write a code for recently viewed products? I use a database to create dynamic pages and thought I could store the ID number in a session or cookie and pull the image and title from the database. Although, I didn't know if this would work. I would only want it to display the last 5 items viewed and not show any duplicates. Any Ideas?
The conventional way would be to store within a cookie. If you can encrypt the cookie, do so.
Remember, a cookie can be modified by the user. The #1 rule is to never trust user input. All in all, be sure to validate the information before displaying or you'll open yourself up to the world of attacks.
Store the IDs in an array? Seperate by ',' or '.' -- do NOT create 100 different cookies for storing IDs.
You COULD also use SQL to store the views... but why use un-needed sql queries? SQL is for storage, long term. Session and cookies are for current actions.
If the user is logged in, you can create a table called 'userViews' providing the userID and the viewed productID. Then, you can select a query using 'SELECT DISTINCT' on the productID. This will select unique values. (Check http://www.w3schools.com/sql/sql_distinct.asp)
If the user is not logged in, I suggest you do the same but instead of using a userID, try to find something unique from the user. You could try setting a cookie or session with a random (unique) number and link that to the database.
There are 3 ways you can show recently viewed products. (Maybe some other way but these 3 are mostly used).
Based on IP
This isn't a good idea, it's because there is chance two people are using same router and the person who did not see the product would see the other person recent view. (You may use IP based to show other people like in your area. etc..).
Based on Cookies
By using cookies you are 100% sure that your are display recent product to the person who is visiting your sites, but not all users/visitors have enabled the cookies also cookies can easily edit and a security risk if you did not encrypt properly.
Session ID
You can generate a random user_id for a visitors and store this information in database like this:
start_session();
if(!$_SESSION['user_id']){
$_SESSION['user_id'] = rand(1, 1000000);
mysql_query('INSERT INTO products_recent (user_id) VALUES ('.$_SESSION['userid'].')');
}
Also, you can select/update the user product views and display to that users.
And you can easily clean database every 24 hours if you want, or you can use this data for analysis purpose.
Finally - Registered Users
If register users view your product I high recommend save in database and show these recent view product every time he/she visit your store.
Thanks,