Checking blockchain data from a smart contract

inspired by some Etherium DApps, an NFT owner can get benefits like DApp’s pricing reduction automatically, is that possible to be implemented by Algorand smart contracts keeping the absolute truth only on-chain ?
For example :
let’s say we have a smart contract that redirect each callback depending on transaction sender : if the sender is the owner of NFT “X” then he will get 2% instead of regular DApp fees 5%… so the question is how can the contract knows that, of course we can’t put all VIP addresses on the contract because of the huge size, so Iam looking to find an efficient way to do so.
Thank you for your help

there are multiple NFT standards…

with arc72 you store onchain information who is the owner of the specific asset and can do some logic in some method where you resell the nft…

see our submission to the last hackathon for the ticketing application: shindg-contract/projects/shindg-contract/contracts/Shindg.algo.ts at main · scholtz/shindg-contract · GitHub

Amazing @scholtz, is that possible using Pyteal ?

Okay @scholtz I think I have understand the idea from Arc72, to be honnest I think that implementing NFTs within protocol layer as standard assets is much better, especially if trading them is an option, however the tickets example was so helpful.

watch out… pyteal is old language which new projects should not use… púte python is now available… just run algokit init

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Thank you @scholtz for the recommendation

You could use an oracle to supply the data feed within the contract.

With something like GORA network you could create the data feed which is then propogated to their nodes and then you could take that info in within the contract by interacting with GORA smart contracts.

We’re doing a similar thing at CompX - will be providing our pricing and ASA info from our database that’s off-chain as a data feed so we can use our data within the contracts

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@Xxiled interesting, why should I do that instead of feeding my contract with just boxes ?

It depends - how are you going to update those boxes? If you expose any of the data you’re passing into your smart contract in web requests prior to sending via txn you open up an avenue for attack.
So oracles allow sensitive data to be transferred/read on chain without being exposed

@Xxiled I will update boxes manually each time NFTs collection will be changed, there is no risk at all because all what the contract should do is checking NFT’s validity from the box