README.md

SUMilanCertificateUpgradeable

This Smart Contract is written in Solidity and uses OpenZeppelin's libraries to generate EIP-721 compliant NFTs.

How it works

The Contract has a main function named mintCertificate that can be invoked only by the contract's owner. The contract's owner is defined at deployment, when the initialize function is called.

The Contract is upgradeable thanks to the OpenZeppelin's Upgrades libraries.

API

SUMilanCertificateUpgradeable contract extends these contracts:

• ERC721Upgradeable
• ERC721URIStorageUpgradeable
• ERC721EnumerableUpgradeable
• OwnableUpgradeable
• Initializable
• UUPSUpgradeable

All the methods of these contracts are available inside SUMilanCertificateUpgradeable instance.

mintCertificate (public onlyOwner)

mintCertificate(address to, string memory tokenUri, string memory eventId)

Checks inside the _certificateOwners mapping if the to address already has a certificate with that eventId. If not, it mints the new certificate.

It's invokable only by the certificate owner.

Parameters:

Name	Type	Required	Description
to	address	yes	Address receiving the minted certificate
tokenUri	string	yes	IPFS hash of the NFT JSON metadata (see ERC721 Metadata JSON Schema)
eventId	string	yes	Event ID for which the certificate is required

Returns

• tokenId (uint256): the token ID of the minted NFT (see Enumerable extension).

_certificateOwners (private)

struct EventsOwned {
    mapping (string => bool) eventIds;
}

mapping (address => EventsOwned) private _certificateOwners;

Associates to every address the eventIds of which it has a certificate.