open-trade.md

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meta property content og:title Developers Guide - Open a Trade meta name content description Guide for programatically executing a trade on Berps. meta property content og:description Guide for programatically executing a trade on Berps.

Berps Developer Guides: Open a Trade

This guide walks through the process of programatically executing trades on Berps, using TypeScript and Ethers.js. This article assumes usage on the Berachain V2 Testnet - please adapt contract addresses and providers to your specific environment.

Step 1: Import Dependencies & Define Constants

First, import the necessary dependencies and define constants, including the relevant trading contract address, Pyth endpoint and the Price Feed IDs for the relevant assets. Here, ETH/USD and USDC/USD feeds are used.

import { ethers } from "ethers";
import { EvmPriceServiceConnection } from "@pythnetwork/pyth-evm-js";

const ENTRYPOINT_CONTRACT_ADDRESS = "0xb3395EeeA7701E0037bBC6Ab52953C6fB0c3326c";
const PYTH_ENDPOINT = "https://hermes.pyth.network";
const PRICE_ID =
  "0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace";
const USDC_PRICE_ID =
  "0xeaa020c61cc479712813461ce153894a96a6c00b21ed0cfc2798d1f9a9e9c94a";

const EntrypointContractABI = ... // See below

Step 2: Set up Providers

Create an instance of an Ethers.js signer and connect to the Berps trading contract and the Pyth price provider:

const signer = new ethers.Wallet(YOUR_PRIVATE_KEY, ETHERS_PROVIDER);

const tradingContract = new ethers.Contract(
  ENTRYPOINT_CONTRACT_ADDRESS,
  EntrypointContractABI,
  signer
);
const pythConnection = new EvmPriceServiceConnection(PYTH_ENDPOINT);

Step 3: Fetch Price Updates and Execute Trade

We require two things from Pyth oracles in order to execute a trade:

1. The current asset price (to inform our trade execution price, converted to 10 decimal places)
2. A signed price update (to update Berp's internal price oracle)

The openTrade function takes the arguments below, explained in further detail here. Pyth requires an update fee for each price update, which is passed in as the value argument (set at 2 wei in this example).

const [priceUpdateData, priceFeeds] = await Promise.all([
  pythConnection.getPriceFeedsUpdateData([PRICE_ID, USDC_PRICE_ID]),
  pythConnection.getLatestPriceFeeds(PRICE_ID),
]);

const { price, expo } = priceFeeds[0].getPriceUnchecked();
const priceInTenDec = parseFloat(price) * Math.pow(10, 10 + expo);

const trade = {
  trader: signer.address,
  pairIndex: 1, // Corresponds to trading pair (ETH-USD)
  index: 0, // Contract will determine
  initialPosToken: 0, // Contract will determine
  positionSizeHoney: ethers.parseEther("10"),
  openPrice: priceInTenDec,
  buy: true,
  leverage: 2n,
  tp: 0n,
  sl: 0n,
};

const orderType = 0; // 0 for MARKET, 1 for LIMIT
const slippage = ethers.parseUnits("3", 10); // 3% slippage

const tx = await tradingContract.openTrade(
  trade,
  orderType,
  slippage,
  priceUpdateData,
  { value: "2" }
);

ABI

The relevant part of the EntrypointContractABI containing the openTrade function is as follows:

[
  {
    "type": "function",
    "name": "openTrade",
    "inputs": [
      {
        "name": "t",
        "type": "tuple",
        "internalType": "struct IOrders.Trade",
        "components": [
          { "name": "trader", "type": "address", "internalType": "address" },
          { "name": "pairIndex", "type": "uint256", "internalType": "uint256" },
          { "name": "index", "type": "uint256", "internalType": "uint256" },
          {
            "name": "initialPosToken",
            "type": "uint256",
            "internalType": "uint256"
          },
          {
            "name": "positionSizeHoney",
            "type": "uint256",
            "internalType": "uint256"
          },
          { "name": "openPrice", "type": "int64", "internalType": "int64" },
          { "name": "buy", "type": "bool", "internalType": "bool" },
          { "name": "leverage", "type": "uint256", "internalType": "uint256" },
          { "name": "tp", "type": "int64", "internalType": "int64" },
          { "name": "sl", "type": "int64", "internalType": "int64" }
        ]
      },
      {
        "name": "orderType",
        "type": "uint8",
        "internalType": "enum ISettlement.TradeType"
      },
      { "name": "slippageP", "type": "int64", "internalType": "int64" },
      {
        "name": "priceUpdateData",
        "type": "bytes[]",
        "internalType": "bytes[]"
      }
    ],
    "outputs": [],
    "stateMutability": "payable"
  }
]