Question

I am hoping to use the PayPal Pro Hosted Solution to handle payments for my website, and what i would like to achieve is that user submitted data is NOT inserted into my database until PayPal confirms i have received payment for their entry.

From what I’ve read, i understand the IPN is the best way to achieve this.

So at the moment, users are entering their data with a form, which i am then previewing to them, and if they approve their entry, i am inserting into a database (using PHP/MySQL). The form data at the moment is being passed along in SESSION variables and working fine. The file process is:

1. User enters data
2. User is presented with their entered data on a knew page and if they approve…
3. They click a button which handles the insert into the database.

However what i would like to do is, if they approve their entry on the preview page, when they click approve, instead of the database being updated there and then, send them to PayPal to make the payment and only update the database with their entry if the payment is approved, like this:

1. User enters data
2. User is presented with their entered data on a knew page and if they approve…
3. They click a button which takes them to the payment page
4. If payment is received, their data is added to the database.

Does anyone have any experience of this type of approach point me in the right direction or give me some guidance on how to go about this please?

I have looked over the PayPal documentation but because I’m new to this, i need things explained in a pretty simple manner.

My original idea was just to store the form is SESSION variables but i will lose this by redirecting people to the payment page. Another thought i had was to create an identical database to what i already have as a temporary holding stage for data, then if the IPN comes back approved, move the data to the final hosting database, but this seems like over engineering the problem a bit.

I hope someone can help.

Thanks
Dan

Answer 1

One matter to recognize regarding IPN is that it is an ‘Asynchronous’ response from PayPal – it is not in the user’s browser session, so session variables will not work if you are relying exclusively on IPN (other than if you receive the IPN response and then match it to the user’s session). PayPal also offers PDT (Payment Data Transfer) which is an ‘in-session’ response which could return the user to your site.

I would not rely exclusively on IPN for payment notifications (see my answer in the following SO topic) Can one rely on Paypal IPN solely to record purchases?.

Our system uses a combination of both IPN and PDT, with the ‘cart’ data stored in a DB (as your ‘temporary’ record) until notification of the completed payment by either PDT or IPN – whichever arrives first which completes the transaction (your ‘permanent’ database insertion) and deletes the ‘temporary’ record (so a subsequent IPN or PDT does not trigger a duplicate transaction).