I have finally got my paypal system working using IPN and a reservation system to ensure that two people do not buy the same product.
The problem is, the reservations last for 10 mins on my application. If a user reserves the product the 'timer' starts, he clicks pay and ends up on paypals website. He then leaves the computer for 10 mins and comes back. He then buys it. By now though the reservation is up and it is possible that someone else could have already bought it.
Is it possible to send a time limit with the paypal IPN request to stop this happening?
As far as I know, you cannot specify that a transaction has to close within a certain amount of time with paypal.
However, I see two options you can use:
Offer a full refund if they purchase and the product is not available. You would check during the ipn notification of the purchase and if it is not available, then refund. You might be penalized by paypal if this happens a lot, but I don't have a lot of experience with offering refunds.
You can specify that the button needs to check inventory see "Step 2 – Tracking Inventory With Your Buy Now Button" in the standard payments guide. Once the product becomes sold out, you use the api to notify paypal the inventory is zero (if there is an api, you might have to use the website for this), and they should be able to notify the user there is zero inventory. I don't have experience with this either, but it seems more complicated than #1, and I would probably go with #1 if this didn't happen a lot. I think in the end you still end up having to issue a refund if the user goes through with the transaction even after seeing there is zero inventory, but I'm not sure about the wording in the docs.
Related
I'm very new with ecommerce sites and making payments online. I'm building a website for a racetrack company. I built my customer a website where you can order subscriptions, rent gear & rent track days. I got paypal to the point where it is returning to me an IPN and I'm getting the response code coming back as either "Pending" or "Completed".
Once a customer makes a payment I need to update in the database the spots they took up, the gear they rented etc to keep inventory correct.
My question is what is the proper protocol for handling this? Should I assume the payment is good if it comes back as "Pending" & fill up all of the spots in my database & if it later comes back as anything other than "Completed" undo everything? Or is there a better way of handling this?
Also, is there other repsonse codes I should be concerned with from the Paypal IPN?
Finally, is there a way for me to only allow instant payments that I know for sure have gone through so I don't have to deal with 'pending' payments?
Any and all advice on Paypal IPN repsonses and anything related to this is very helpful as I need to release this site in 2 weeks and I want to make sure I don't do something wrong with this.
is there a way for me to only allow instant payments
There is an account level setting (Payment Receiving Preferences):
In REST API:
the intent set to sale "is for immediate payment"
payment_options of transaction (INSTANT_FUNDING_SOURCE)
For good measure, you should still check the status though (for other reasons that might set the status to pending - in the link referenced in comments above, e.g. currency/fraud settings, etc.) and handle according to your business rules..
Hth..
I'm selling from my php site and I accept paypal payments, I've got a limited number of products, buyers have them in their carts, and availability is not enough for them all.
If they pay with paypal at the same time I need to refound one of them.
Is this approach correct, or is it preferable to check availability before the payment IPN notification?
That sounds like a poor user flow. Once you get verification that an item is sold, reduce your inventory in your database. Before sending them to Paypal, verify that you have enough inventory to fulfill their order.
If you get a scenario where say you have one item left and two users were directed to Paypal to purchase it, whoever you receive notification of successful payment first, gets it. The other, you can do a few things:
Place the item on backorder, let the user know when it'll come in with an estimate. When it comes in, send it to them.
Allow the user to choose whether they want the backorder, or to cancel their order, in which case they get a refund
If, once a product sells out, there are none left forever, you can immediately issue a refund.
I have been developing an online retail shop.
It is written in php and uses paypal and IPN to handle payments.
I have written my own shopping cart. When the user wants to checkout they click on the checkout button which has the standard cart upload function wrapped around the button and the user is taken to paypal to complete payment. Paypal then sends me an IPN to notify me of the payment.
My question is, at what point should I store the order and when should the stock levels be reduced?
The standard process flow is that I have right now is as follows:
User adds item to cart.
If item is now sold out or the quantity added is more than available, the cart is updated to reflect this.
However, stock added to the cart does not reduce stock levels.
User clicks checkout.
The cart is loaded into an order record in the db AND the stock levels are reduced.
User is taken to paypal to complete payment.
(a) User completes payment.
(b) User does not complete payment by either returning to website or going somewhere else / closing browser.
(Optional) User clicks return to website.
User sees a 'thank you, order complete' complete page.
Nothing is processed relating to the order table since paypal will send IPN anyway.
Paypal sends IPN
Update order with the transaction status
As you may see, there are some issues with this process. If the customer leaves the paypal page without completing payment I will have a 'dangling' order and since stock levels are also reduced this stock will not be available to other customers! A solution to this is to manually 'clean' the database every so often.
Alternatives?
option I) Do not store the order in the database until a 'completed transaction' IPN is received, then use the cart info stored in the session to create an order and reduce stock levels. However, sessions can expire and paypal payments might take days depending on payment.
option II) Store the order as is now but do not reduce stock levels until completed transaction IPN is received. This still has the issue of dangling orders but at least no stock will have to be re added again when cleaning up, I'll just have to remove the orders. Another problem with this though is that if multiple people order at similar times and thus collectively their orders contain quantities that exceed stock. This could be quite chaotic when the system receives completed IPNS and then reduces stock levels to negative quantities!
I have looked everywhere on the internet for some sort of help, but it is not mentioned anywhere! Everyone just skips to how IPN should be handled. I just don't understand how other people could not have had this problem?!
Please help!
You're dealing with the same problem that airline reservation systems have for ages. Use the same solution ie
1.Upon user clicking checkout (while being redirected to Paypal)
reduce inventory count
place a timestamp in the database along with a state that this order is temporary
2a. Once you receive an IPN ie know the billing has been successful
change state of the order to permanent
2b. Have a cron job that runs every few minutes to track temporary orders. If temporary orders are from a time greater than what you allow eg 20 mins then:
remove the temporary order from database
undo the change in inventory count
As both a merchant and a developer, I prefer to adjust inventory stock with the IPN, even if that IPN is pending (eg. an eCheck). The chance of 2 customers going through checkout at the same time with your last remaining stock is typically low. If you do have high enough volume and low stock levels (why would you?) then you may want to do something in the cart to place locks on the items for the duration of the session timeout.
Make sure your order processing code returns the inventory to stock if the order is canceled or returned.
The situation is like this,
I have three kind of user registration on my site
$20/month
$30/month
$40/month
now, suppose a user registers with $30 amount and takes the 2nd registration...
next 2 months his $30 per month were deducted as per the recurring payment of paypal...working fine .:)
Now, he wants to upgrade to $40 i.e 3rd membership , so from next month his amount deduction should be $40... How to update paypal for this change in amount..
I DON'T WANT TO GO TO PAYPAL'S SITE FOR THIS...
Is there any API for this purpose.......
Any help would be appreciated....
First off, Paypal's API is not a simple or easy thing to use, but what you're asking can be done. It is simply a matter of canceling the existing 'recurring payment profile' via the API, and starting another recurring payment that ends at the same time.
The API methods themselves change depending on which system you are using. At my company, we use Paypal Website Payments Pro. This has a specific set of functions to perform actions. Without knowing which system you use, however, we can't give any further advice.
The below link shows a number of the methods for the different Paypal API's. Do your research, and try to ask specific questions. :)
https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/howto_api_reference
Daniel Moniz
I was able to do this, but first, this caveat from PayPal should be noted:
Note: For recurring payments with Express Checkout, the payment amount can be increased by no more than 20% every 180 days (starting when the profile is created).
Since I'm not using Express Checkout, POSTing this worked for me to change an amount from $75 to $200 (the credentials are fake):
TRXTYPE=R&TENDER=C&PARTNER=PayPal&VENDOR=Acme&USER=Acme&PWD=a1b2c3d4
&ACTION=M&AMT=200.00&ORIGPROFILEID=RP0000001234
The other caveat is that this is only one of I-don't-know-how-many APIs and I-don't-know-how-many-types-of-accounts (in this case Payflow) that PayPal has, and I don't know if something similar works for all of them. The above code is actually copied almost verbatim (credentials and amount changed) from https://developer.paypal.com/docs/classic/payflow/recurring-billing/.
I'm creating a simple online shop with PHP integrated with PayPal that sells unique items. What I'm wondering is how other shops deal with multiple people attempting to go through the payment process with the same item.
This is my current draft strategy:
Items have three status types: available, on hold & sold.
As a user moves to the PayPal payment page it checks the status of all the items in the cart to ensure they're available. It also sets the item's status to "on hold" until they either come back after payment is confirmed or it times out (10 minutes? Not sure what this should be).
Is this standard practice or is there a more practical way I should be going about this?
Thanks in advance!
Have a look at Dell's UK outlet. When someone adds a system to their shopping basket it is held and not available to other customers. If it isn't purchased, the item is removed from the basket after 15mins of inactivity and is then available to other customers.
I would say the first part of your strategy is correct - as you move to the payment page, flag all the products as 'on hold'
When the user has finished the payment, you will get a postback from Paypal which lets you know if the authorisation was successful or not (and possibly also allows you to check the CSC/CVV2 result), and at that point you have the option of either accepting the payment, or rejecting it.
On receipt of the postback you should also check whether the items are still on hold. If they have timed out you can reject the payment and display a message 'sorry - timeout exceeded' or somesuch.
This method also allows you to work out an ideal timeout period if you keep track of how often customers run into the timeout, so you can extend the timeout from (eg) 5 to 10 minutes if too many are timing out, or shorten it if none are timing out.
This is a fairly common issue with fixed inventory systems such as venue, transport/airline tix etc.
I like the airline model where once you get the itinery you want and click select, you get a page with passenger info with a message saying, seats on hold and you now have xx(10/15) minutes to complete the purchase. Everything becomes explicit at that time. For other unique/one of a kind item, I'd think a message on any page, that the user clicks on, saying you have xx(mins) remaining to complete the purchase would be a big motivator for "on the edge" buyers !
woot.com is notorious for this problem but their solution works well. After payment information is verified the user is brought to a page with a small amount of text saying something like "your order is in, we are verifying inventory".
It looks like the paypal API has a "RefundTransaction" message so something like that might not be possible. But the user experience could be awkward if your going to the paypal website then coming back to your site.
This is much like booking theatre tickets or similar online and yes the way you describe is generally the way it works. At some point the item is "reserved" in the system and either the customer completes the transaction or the item is released after some time for others to buy.
Of course at what point you reserve the item (when it's added to the cart, at the point you send them off to pay etc) is up to you. I would expect putting it in the cart would be the best choice as it makes it less likely someone will build up a basket of stuff only to find half of it is no longer available at the checkout.