Getting the Unique Transaction ID seen by the customer from Express Checkout

Question

I'm using PayPal Express Checkout on a sandbox account, and i'm trying to link up the Unique Transaction ID on the "customer" paypal site with the completed transaction via Express Checkout.

My DoExpressCheckoutPayment returned:

TOKEN=EC%2d2KG36160AM8868619&
SUCCESSPAGEREDIRECTREQUESTED=false&
TIMESTAMP=2015%2d01%2d29T09%3a45%3a09Z&
CORRELATIONID=44060412ed341&
ACK=Success&
VERSION=93&BUILD=15009693&
INSURANCEOPTIONSELECTED=false&
SHIPPINGOPTIONISDEFAULT=false&
PAYMENTINFO_0_TRANSACTIONID=011446947E558235S&
PAYMENTINFO_0_TRANSACTIONTYPE=expresscheckout&
PAYMENTINFO_0_PAYMENTTYPE=instant&
PAYMENTINFO_0_ORDERTIME=2015%2d01%2d29T09%3a45%3a08Z&
PAYMENTINFO_0_AMT=7%2e98&
PAYMENTINFO_0_FEEAMT=0%2e47&
PAYMENTINFO_0_TAXAMT=0%2e00&
PAYMENTINFO_0_CURRENCYCODE=GBP&
PAYMENTINFO_0_PAYMENTSTATUS=Completed&
PAYMENTINFO_0_PENDINGREASON=None&
PAYMENTINFO_0_REASONCODE=None&
PAYMENTINFO_0_PROTECTIONELIGIBILITY=Ineligible&
PAYMENTINFO_0_PROTECTIONELIGIBILITYTYPE=None&
PAYMENTINFO_0_SECUREMERCHANTACCOUNTID=W9SM36U76AXSS&
PAYMENTINFO_0_ERRORCODE=0&
PAYMENTINFO_0_ACK=Success

Then my GetExpressCheckoutDetails returned:

TOKEN=EC%2d2KG36160AM8868619&
BILLINGAGREEMENTACCEPTEDSTATUS=0&
CHECKOUTSTATUS=PaymentActionCompleted&
TIMESTAMP=2015%2d01%2d29T09%3a45%3a33Z&
CORRELATIONID=80e00a0067bea&
ACK=Success&
VERSION=93&
BUILD=15009693&
EMAIL=test1%40sud%2eco2euk&
PAYERID=H54VEN293PLFL&
PAYERSTATUS=verified&
FIRSTNAME=Test&
LASTNAME=User&
COUNTRYCODE=GB&
CURRENCYCODE=GBP&
AMT=7%2e98&
SHIPPINGAMT=0%2e00&
HANDLINGAMT=0%2e00&
TAXAMT=0%2e00&
INSURANCEAMT=0%2e00&
SHIPDISCAMT=0%2e00&
PAYMENTREQUEST_0_CURRENCYCODE=GBP&
PAYMENTREQUEST_0_AMT=7%2e98&
PAYMENTREQUEST_0_SHIPPINGAMT=0%2e00&
PAYMENTREQUEST_0_HANDLINGAMT=0%2e00&
PAYMENTREQUEST_0_TAXAMT=0%2e00&
PAYMENTREQUEST_0_INSURANCEAMT=0%2e00&
PAYMENTREQUEST_0_SHIPDISCAMT=0%2e00&
PAYMENTREQUEST_0_TRANSACTIONID=011446947E558235S&
PAYMENTREQUEST_0_INSURANCEOPTIONOFFERED=false&
PAYMENTREQUESTINFO_0_TRANSACTIONID=011446947E558235S&
PAYMENTREQUESTINFO_0_ERRORCODE=0

But the customer site says:

PayPal Express Checkout Payment Sent (Unique Transaction ID 7PK53077PJ222701T)

Answer 1

Oh..the (painful) memories :) That aforementioned "oddity" also exists elsewhere - e.g. eBay transactions

IINM, you'll need to send your own "custom ID" - the Invoice Id mentioned above (which is displayed to the end user) so both ends have some visual reference to a transaction.

In the REST API (unsure in Classic, haven't tried), if you send an Order, the Order Number (finally) is shared on both ends (same for both). Though it wouldn't hurt to still send your own "custom Id"/"Invoice Id".

Buyer/Customer Paypal UI:

Seller/Merchant Paypal UI: Hth...