How to create an Erc721 contract with fixed dollar price per token (eg. 1 nft should always cost 200$, irrespective of the ether price)

Question

I'm creating an Erc721a contract and I want to set the price of my tokens to 200$, and for that I used chanlink's aggregator v3 interface which returns the dollar value, but how should I use this ? If there's any sample code or any smart contract with same functionality, please share !! Thanks.

Answer 1

You can write it for example like this

    function getLatestPrice() public view returns (int) {
        (
            /*uint80 roundID*/,
            int price,
            /*uint startedAt*/,
            /*uint timeStamp*/,
            /*uint80 answeredInRound*/
        ) = priceFeed.latestRoundData();
        return price;
    }
    
    function mint() public payable returns(uint256 tokenId) {
        int oneEthInUsd = getLatestPrice(); // 1 ETH in terms of USD
    
        // If 1 ETH = 3274,72773030 USD

        // 1 ETH : 3274,72773030 USD = X ETH : 200 USD
        // X = 1 * 200 / 3274,72773030

        int twoHundredUsdInEth = 200 ether / oneEthInUsd; 
        require(msg.value >= uint(twoHundredUsdInEth), "The Price is 200 USD"); 

        // the rest of your minting function logic
  }

Answer 2

Consider using $DAI or $USDC for the minting payment instead of price feed from oracle.