How to get how many tokens are left to mint from an ERC721 smart contract that implements a max supply?

Question

I have an ERC721 that implements a public maxSupply value, so I cannot mint more than a certain amount of tokens.

Thanks to the public modifier, this exposes a method I can call to see what the maxSupply is.

I can then perform maxSupply - totalSupply (considering that my ERC721 implements ERC721Enumerable extension as well) to know how many tokens are left to mint.

But, as I understand, the maxSupply function is not part of the IERC721 nor the IERC721Enumerable interfaces.

Does this mean that if I want to call this method from another smart contract I should create my own interface?

Answer 1

Yes, If you want to interact with the maxSupply function from another smart contract, you should create your own custom interface. Here's an example:

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol";

interface ICustomERC721 is IERC721Enumerable {
    function maxSupply() external view returns (uint256);
}