Methods Overview

We’ll cover two main ways to take offers:

1. Fixed Pricing – A set price defined by the maker.
2. Dynamic Pricing – Rates pulled from on-chain price feeds, with a customizable slippage cap.

Depending on the offer’s takingOfferType, you may need to take the full amount (BlockOffer) or can take any partial amount (PartialOffer).

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1. takeOfferFixed

function takeOfferFixed(
    uint256 offerId,
    uint256 withdrawalAmountPaid,
    address affiliate
) external;

What it does: You pay a fixed amount of the withdrawal asset to the maker, and receive the maker’s deposit asset from escrow.

Tip: If the offer is a BlockOffer, you must supply the full remaining amount. For PartialOffer, you can supply any amount up to what’s left.

Parameters:

Possible Errors:

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2. takeOfferDynamic

function takeOfferDynamic(
    uint256 offerId,
    uint256 withdrawalAmountPaid,
    uint256 maximumDepositToWithdrawalRate,
    address affiliate
) external;

What it does: Fetches live rates for your assets, caps slippage at maximumDepositToWithdrawalRate, then swaps your withdrawal asset for the maker’s deposit asset.

Tip: We recommend to copy the depositToWithdrawalRate from the API dotc_offers response. If you set maximumDepositToWithdrawalRate to 0, it will use the current rate without any extra cap.

Parameters:

Possible Errors:

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Usage Tutorial

Examples use TypeScript & Ethers.js You can adapt these steps to any language or library.

1. Prerequisites

• Node.js ≥ 16, plus Yarn or npm
• A Polygon RPC endpoint (e.g. https://polygon-rpc.com/, Alchemy, Infura—any will work)
• A wallet with enough of the withdrawal token (e.g. USDC)
• (Optional) API token for dotc_offers: https://rfq.swarm.com/v1/client/

2. Full Example Script

Below is a complete script that fetches offers, approves your token, and takes an offer based on its pricing type. Copy, update your private key, API key, then run!

import { ethers } from "ethers";

async function main() {
  // 1. Fetch offers from the API
  const response = await fetch(
    "https://rpq.swarm.com/v1/client/dotc_offers?page=0&limit=1&network=polygon&withdrawalAssetSymbol=USDC",
    {
      headers: { "X-API-Key": "API_KEY" }
    }
  );
  const { offers } = await response.json();

  // 2. Setup wallet and contracts
  const PRIVATE_KEY = "a3f...";  // ← your wallet private key
  const RPC_URL      = "https://polygon-rpc.com/";  // ← any valid RPC endpoint
  const DOTC_ADDRESS = ethers.getAddress("0x22593b8749a4e4854c449c30054bb4d896374fa1"); // ← our DOTC contract address for your network (polygon in this example)

  const provider = new ethers.JsonRpcProvider(RPC_URL);
  const wallet   = new ethers.Wallet(PRIVATE_KEY, provider);
  const dotc     = new ethers.Contract(
    DOTC_ADDRESS,
    [
      "function takeOfferFixed(uint256,uint256,address)",
      "function takeOfferDynamic(uint256,uint256,uint256,address)"
    ],
    wallet
  );

  // 3. Approve the withdrawal token
  async function approveToken(tokenAddress: string, amount: bigint) {
    const erc20 = new ethers.Contract(
      tokenAddress,
      ["function approve(address,uint256) external"],
      wallet
    );
    const tx = await erc20.approve(DOTC_ADDRESS, amount);
    console.log("Approval tx hash:", tx.hash);
    await provider.waitForTransaction(tx.hash);
    console.log("✔️ Token approved!");
  }

  // 4a. Take a fixed-price offer
  async function takeFixed(
    offerId: bigint,
    amount: bigint,
    affiliate: string = ethers.ZeroAddress
  ) {
    const tx = await dotc.takeOfferFixed(offerId, amount, affiliate);
    console.log("takeOfferFixed tx hash:", tx.hash);
    const receipt = await provider.waitForTransaction(tx.hash);
    console.log("✔️ Fixed offer taken!", receipt);
  }

  // 4b. Take a dynamic-price offer
  async function takeDynamic(
    offerId: bigint,
    amount: bigint,
    maxRate: bigint,
    affiliate: string = ethers.ZeroAddress
  ) {
    const tx = await dotc.takeOfferDynamic(offerId, amount, maxRate, affiliate);
    console.log("takeOfferDynamic tx hash:", tx.hash);
    const receipt = await provider.waitForTransaction(tx.hash);
    console.log("✔️ Dynamic offer taken!", receipt);
  }

  // 5. Execute based on pricing type
  const offer = offers[0];
  const offerId = BigInt(offer.id); // convert hex id to decimals
  const amountIn = BigInt(offer.amountIn); // by passing amountIn we can take the whole offer

  // Approve
  await approveToken(offer.withdrawalAsset.address, amountIn);

  if (offer.offerPrice.pricingType === "FixedPricing") {
    await takeFixed(offerId, amountIn);
  } else if (offer.offerPrice.pricingType === "DynamicPricing") {
    const maxRate = BigInt(offer.depositToWithdrawalRate);
    await takeDynamic(offerId, amountIn, maxRate);
  }
}

main();

3. Run It

Use any online IDE (replit, codesandbox, etc) or save as trade.ts, then:

npm install ethers
npx ts-node trade.ts