How to check payment by note?

Question

API

I saw this type of payment for goods in many less popular stores - a person clicks on the buy button and he is invited to transfer money to a Qiwi number or Yandex.Money wallet with a certain comment (note), after which he confirms his payment. So, how can you check the receipt of a payment with a comment? Please push in the right direction, I did not find decent answers on the Toaster.

Answer 1

1. Through the API.
2. Letter in the mail.

Answer 2

Can be implemented through the wallet API. (no need to connect the store, everything is simple) -
https://developer.qiwi.com/ru/qiwi-wallet-personal...
There is an actual library in php - https://github.com/Mirovich/qiwi
I see 2 solutions Problems:
1) You can request information about a transaction by its ID. (you set the id when you form the payment)
https://developer.qiwi.com/en/qiwi-wallet-personal...
2) You can upload the payment history to an array and sort through comparing the notes.
https://developer.qiwi.com/ru/qiwi-wallet-personal...