Add auction function to marketplace contract

hey community , I am also pretty new for this area, I would like to ask how can add Auction function to my marketplace contract. There is many auction contract as I understood but I will add blind auction to my marketplace. I start to write already blindauction but I don’t know how I can add that to marketplace contract. until know I can mint and list item. thank you so much

this is my marketplace contract

pragma solidity ^0.8.0;

import "../node_modules/@openzeppelin/contracts/token/ERC721/IERC721.sol";

contract NftMarketContract {
    struct AuctionItem {
        uint256 id;
        address tokenAddress;
        uint256 tokenId;
        address payable seller;
        uint256 askingPrice;
        bool isSold;

    AuctionItem[] public itemsForSale;
    mapping (address => mapping (uint256 => bool)) activeItems;

    event itemAdded(uint256 id, uint256 tokenId, address tokenAddress, uint256 askingPrice);
    event itemSold(uint256 id, address buyer, uint256 askingPrice);

    modifier OnlyItemOwner(address tokenAddress, uint256 tokenId){
        IERC721 tokenContract = IERC721(tokenAddress);
        require(tokenContract.ownerOf(tokenId) == msg.sender);

    modifier HasTransferApproval(address tokenAddress, uint256 tokenId){
        IERC721 tokenContract = IERC721(tokenAddress);
        require(tokenContract.getApproved(tokenId) == address(this));

    modifier ItemExists(uint256 id){
        require(id < itemsForSale.length && itemsForSale[id].id == id, "Could not find Item");

    modifier IsForSale(uint256 id){
        require(itemsForSale[id].isSold == false, "Item is already sold");

    function addItemToMarket(uint256 tokenId, address tokenAddress, uint256 askingPrice) OnlyItemOwner(tokenAddress,tokenId) HasTransferApproval(tokenAddress,tokenId) external returns (uint256) {
        require(activeItems[tokenAddress][tokenId] == false, "Item is already up for Sale");
        uint256 newItemId = itemsForSale.length;
        itemsForSale.push(AuctionItem(newItemId, tokenAddress, tokenId, payable(msg.sender), askingPrice, false));
        activeItems[tokenAddress][tokenId] = true;

        assert(itemsForSale[newItemId].id == newItemId);
        emit itemAdded(newItemId, tokenId, tokenAddress, askingPrice);
        return newItemId;

    function buyItem(uint256 id) payable external ItemExists(id) IsForSale(id) HasTransferApproval(itemsForSale[id].tokenAddress,itemsForSale[id].tokenId){
        require(msg.value >= itemsForSale[id].askingPrice, "Not enough funds sent");
        require(msg.sender != itemsForSale[id].seller);

        itemsForSale[id].isSold = true;
        activeItems[itemsForSale[id].tokenAddress][itemsForSale[id].tokenId] = false;
        IERC721(itemsForSale[id].tokenAddress).safeTransferFrom(itemsForSale[id].seller, msg.sender, itemsForSale[id].tokenId);

        emit itemSold(id, msg.sender, itemsForSale[id].askingPrice);

The question is not clear. Please try to ask more clearly.

Is the contract already deployed? Otherwise, you should just write the function in the code like the other functions it already has.

Thank you for reply. This is my market contract but i did not deploy yet , i would like add blind auction but i dont know that i should write new contract for auction or can i just add blind auction to this market contract. Actually the problem is i created nft market place and it offers 3 way to create item. One is not for selling just create item , second is instant buy , you can create and list item on market , third function is accept offers , for that i need to add auction to marketplace but i dont know how to do it. Thank you so much

It sounds like you need to learn basic Solidity before working on this marketplace project. You can maybe try Solidity by Example.

Thank you so much actually I found there what I need.

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I’m not OP but thank you, i’ve been hoping to find something like this.

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