React to the updated balance

Tokens & NFTs
1

The following question has been asked on Telegram:

I need to make a interscore call with callback in a function and read the updated db below the interscore call. How can I implement this ?

It’s the same answer as here: Obtaining the user balance of a deployed FA2.

You can then place the reactive code in the setter_ entrypoint.

:warning: Remember to check the sender and add a mechanism to avoid replay because anyone can ask the balance and give your contract as the callback.

2

The code below the interscore call also uses that function parameters. So placing the reactive code in setter_ enrtypoint needs to send all those params in call back functions as well right? Is is the most efficient solution?

3

It is the solution in line with the FA2 standard. Note that the answer also provides a second solution that doesn’t use callbacks, but a view. This is not included in the standard, but more efficient and fine for many use cases.