Dutch Auction Guide

Introduction

The Dutch auction order is used to sell a nft asset with a given start price and end price. The actual match price will decrease linearly.

Dutch Auction And Buy

Select Selector.

Please refer to nft transfer selector guide

Calculate replacementPattern

Please refer to replacement pattern guide

Parse order parameters

Please refer to order event

Generate buy order calldata

Please refer to build calldata

Make Order

Please refer to make order

Take Order

Please refer to take order

Example JS Code

The referenced contracts are located in TestERC20, TestERC721 and NiftyConnectExchange

const nftOwner = accounts[1];
const makerRelayerFeeRecipient = accounts[2];

const niftyConnectExchangeInst = await NiftyConnectExchange.deployed();
const testERC721Inst = await TestERC721.deployed();

// Step 1: mint ERC721 token and setApprovalForAll
const tokenId = await testERC721Inst.tokenIdIdx();
await testERC721Inst.mint(nftOwner, {from: nftOwner});
await testERC721Inst.setApprovalForAll(NiftyConnectExchange.address, true, {from: nftOwner});

// Step 2: calculate list time, expire time and generate random salt
const listtime = Math.floor(Date.now() / 1000);
const expireTime = web3.utils.toBN(listtime).add(web3.utils.toBN(3600)); // expire at one hour later
const salt = "0x"+crypto.randomBytes(32).toString("hex");

// Step 3: set sell price and amount
const exchangePrice = web3.utils.toBN(1e18);
const extraPrice = web3.utils.toBN(1e17);
const ERC721_AMOUNT = web3.utils.toBN(1); // ERC721 amount must be 1

// Step 4: Select Selector. For ERC721
const ERC721TransferSelector = web3.utils.toBN(0);
const ERC721SafeTransferSelector = web3.utils.toBN(1);

// Step 5: Calculate replacement pattern
const sellReplacementPattern = generateBuyReplacementPatternForNormalOrder(false)

// Step 6: make order
await niftyConnectExchangeInst.makeOrder_(
    [
        NiftyConnectExchange.address,                       // exchange
        nftOwner,                                           // maker
        "0x0000000000000000000000000000000000000000",       // taker
        makerRelayerFeeRecipient,                           // makerRelayerFeeRecipient
        "0x0000000000000000000000000000000000000000",       // takerRelayerFeeRecipient
        TestERC721.address,                                 // nftAddress
        "0x0000000000000000000000000000000000000000",       // staticTarget
        TestERC20.address,                                  // paymentToken
        nftOwner,                                           // from
        "0x0000000000000000000000000000000000000000"        // to
    ],
    [
        exchangePrice,                // uint basePrice
        extraPrice,                   // uint extra
        listtime,                     // uint listingTime
        expireTime,                   // uint expirationTime
        web3.utils.toBN(salt),        // uint salt
        ERC721TransferSelector,       // uint merkleValidatorSelector
        tokenId,                      // uint tokenId
        ERC721_AMOUNT,                // uint amount
        0,                            // uint totalLeaf
    ],
    1,                      // side (0 buy,1 sell)
    1,                      // Kind of sale (0 fixPrice buy/sell, 1 Auction) 
    sellReplacementPattern, // replacementPattern
    [],                     // staticExtradata
    [
        "0x0000000000000000000000000000000000000000000000000000000000000000", // merkle root hash, only for trait-based order 
        "0x0000000000000000000000000000000000000000000000000000000000000000"  // ipfs hash which contain the metadata of merkle proof, only for trait-based order 
    ],                      // merkleData
    {from: nftOwner}
);

const currentPrice = await niftyConnectExchangeInst.calculateCurrentPrice_(
    [
        NiftyConnectExchange.address,                       // exchange
        nftOwner,                                           // maker
        "0x0000000000000000000000000000000000000000",       // taker
        makerRelayerFeeRecipient,                           // makerRelayerFeeRecipient
        "0x0000000000000000000000000000000000000000",       // takerRelayerFeeRecipient
        TestERC721.address,                                 // nftAddress
        "0x0000000000000000000000000000000000000000",       // staticTarget
        TestERC20.address,                                  // paymentToken
        nftOwner,                                           // from
        "0x0000000000000000000000000000000000000000"        // to
    ],
    [
        exchangePrice,                // uint basePrice
        extraPrice,                   // uint extra
        timestamp,                    // uint listingTime
        expireTime,                   // uint expirationTime
        web3.utils.toBN(salt),        // uint salt
        ERC721TransferSelector,       // uint merkleValidatorSelector
        tokenId,                      // uint tokenId
        ERC721_AMOUNT,                // uint amount
        0,                            // uint totalLeaf
    ],
    1,                      // side
    1,                      // saleKind
    sellReplacementPattern, // replacementPattern
    [],                     // staticExtradata
    "0x00",                 // merkleRoot
);

console.log("currentPrice: "+currentPrice.toString());

// Take Order

const buyer = accounts[3];
const takerRelayerFeeRecipient = accounts[4];

// Step 1: parse order calldata from event OrderApprovedPartTwo
const orderApprovedPartTwoEvent = expectEvent.inLogs(makeOrdertx.logs, 'OrderApprovedPartTwo');
const sellCalldata = orderApprovedPartTwoEvent.args.calldata;

// Step 2: generate buy order calldata
const buyCalldata = await niftyConnectExchangeInst.buildCallData(
    ERC721TransferSelector, // uint selector,
    "0x0000000000000000000000000000000000000000", // address from,
    buyer, // address to,
    TestERC721.address,// address nftAddress,
    tokenId, // uint256 tokenId,
    ERC721_AMOUNT,// uint256 amount,
    "0x00", // bytes32 merkleRoot
    [],// bytes32[] memory merkleProof
);

// Step 3: Calculate replacementPattern for buyOrder
const buyReplacementPattern = generateBuyReplacementPatternForNormalOrder(false)

// Step 4: Take Order
await niftyConnectExchangeInst.takeOrder_(
    [   // address[16] addrs,
        // buy order
        NiftyConnectExchange.address,                       // exchange
        buyer,                                              // maker
        "0x0000000000000000000000000000000000000000",       // taker
        "0x0000000000000000000000000000000000000000",       // makerRelayerFeeRecipient
        takerRelayerFeeRecipient,                           // takerRelayerFeeRecipient
        TestERC721.address,                                 // nftAddress
        "0x0000000000000000000000000000000000000000",       // staticTarget
        TestERC20.address,                                  // paymentToken

        // sell order
        NiftyConnectExchange.address,                       // exchange
        nftOwner,                                           // maker
        "0x0000000000000000000000000000000000000000",       // taker
        makerRelayerFeeRecipient,                           // makerRelayerFeeRecipient
        "0x0000000000000000000000000000000000000000",       // takerRelayerFeeRecipient
        TestERC721.address,                                 // nftAddress
        "0x0000000000000000000000000000000000000000",       // staticTarget
        TestERC20.address,                                  // paymentToken
    ],
    [   // uint[12] uints,
        // buy order
        exchangePrice,                // uint basePrice
        extraPrice,                   // uint extra
        listtime,                     // uint listingTime
        expireTime,                   // uint expirationTime
        web3.utils.toBN(salt),        // uint salt
        tokenId,                      // uint tokenId
        // sell order
        exchangePrice,                // uint basePrice
        extraPrice,                   // uint extra
        listtime,                     // uint listingTime
        expireTime,                   // uint expirationTime
        web3.utils.toBN(salt),        // uint salt
        tokenId,                      // uint tokenId
    ],
    [   // uint8[4] sidesKindsHowToCalls,
        0, 1,
        1, 1
    ],
    buyCalldata, // bytes calldataBuy,
    sellCalldata, // bytes calldataSell,
    buyReplacementPattern, // bytes replacementPatternBuy,
    sellReplacementPattern, // bytes replacementPatternSell,
    [],// bytes staticExtradataBuy,
    [],// bytes staticExtradataSell,
    "0x00",// bytes32 rssMetadata
    {from: buyer}
);