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NEAR
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Adding on-chain kycNFT checks
Our smart contract deployed on NEAR chain implements a very simple interface which implementing smart contracts can use to quickly check if a certain AccountID has a valid kycNFT.
/// A trait for checking whether an address has a valid kycNFT token
#[ext_contract(kycdao)]
trait KycValidity {
/// Check if an account has any valid tokens
fn has_valid_token(&self, address: AccountId) -> bool;
}You can use the above function in a cross-contract call to check if a given AccountID has valid kycNFT.
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Example
Here is an example of a contract using a cross-contract call to check if the AccountId has a valid kycNFT token.
fn query_kyc(&self, account_id: AccountId) -> Promise {
// Create a promise to call kycdao.has_valid_token()
let promise = kycdao::ext(self.kyc_contract_address.clone())
.with_static_gas(Gas(5*TGAS))
.has_valid_token(account_id);
return promise.then( // Create a promise to callback query_kyc_callback
Self::ext(env::current_account_id())
.with_static_gas(Gas(5*TGAS))
.query_kyc_callback()
)
}
#[private]
pub fn query_kyc_callback(&self, #[callback_result] call_result: Result<bool, PromiseError>) -> bool {
if call_result.is_err() {
log!("There was an error contacting KYC Contract");
return false;
}
// Return the KYC validity, or do some gating with it
let validity: bool = call_result.unwrap();
validity
}