Hi @SolidityDevPrague,
If you want your own minting functionality, then I suggest extending from OpenZeppelin Contracts ERC721 implementation, as you don’t need _tokenIdTracker.
Your mintWithId function looks fine.
You can use _safeMint rather that _mint if you want to enforce that if to is a smart contract it must implement IERC721Receiver.onERC721Received. (see: https://docs.openzeppelin.com/contracts/3.x/api/token/erc721#ERC721-_safeMint-address-uint256-)
If you are set a baseURI, then you don’t actually need to store a uri per token.
e.g. baseURI of https://example.com/tokens/ and tokenID of 1234 then the tokenURI is https://example.com/tokens/1234
Please note, if you are providing the tokenID externally, then you will need to ensure that they are unique otherwise minting will revert.
I did a very quick example:
The following code hasn’t been tested or audited.
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/access/AccessControl.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/GSN/Context.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/token/ERC721/ERC721.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/token/ERC721/ERC721Burnable.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.3.0/contracts/token/ERC721/ERC721Pausable.sol";
/**
* @dev {ERC721} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
* - token ID and URI autogeneration
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract MyNFT is Context, AccessControl, ERC721Burnable, ERC721Pausable {
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* Token URIs will be autogenerated based on `baseURI` and their token IDs.
* See {ERC721-tokenURI}.
*/
constructor(string memory name, string memory symbol, string memory baseURI) public ERC721(name, symbol) {
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setBaseURI(baseURI);
}
/**
* @dev Creates a new token for `to`. Its token ID will be automatically
* assigned (and available on the emitted {IERC721-Transfer} event), and the token
* URI autogenerated based on the base URI passed at construction.
*
* See {ERC721-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 tokenId) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "MyNFT: must have minter role to mint");
_mint(to, tokenId);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC721Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "MyNFT: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC721Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "MyNFT: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override(ERC721, ERC721Pausable) {
super._beforeTokenTransfer(from, to, tokenId);
}
}
