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How to use real-time data in TON contracts

Pyth is a pull oracle. Pyth price feeds on TON are managed through the main TON Pyth smart contract, enabling seamless interaction with on-chain data. In TON, these interactions are facilitated by specific functions within the Pyth TON contract. This contract acts as an interface to Pyth price feeds, handling the retrieval and updating of price data.

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Install the Pyth SDK

Install the Pyth TON SDK and other necessary dependencies using npm or yarn: 
npm install @pythnetwork/pyth-ton-js @pythnetwork/hermes-client @ton/core @ton/ton @ton/crypto

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Write code to interact with oracle

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Off-chain data fetch and update

The following code snippet demonstrates how to fetch price updates, interact with the Pyth contract on TON, and update price feeds: The following example uses the testnet contract. For mainnet usage, change the PYTH_CONTRACT_ADDRESS_TESTNET to PYTH_CONTRACT_ADDRESS_MAINNET accordingly. 
import { TonClient, Address, WalletContractV4 } from "@ton/ton";
import { mnemonicToPrivateKey } from "@ton/crypto";
import { HermesClient } from "@pythnetwork/hermes-client";
import {
  PythContract,
  PYTH_CONTRACT_ADDRESS_TESTNET,
  PYTH_CONTRACT_ADDRESS_MAINNET,
  calculateUpdatePriceFeedsFee,
} from "@pythnetwork/pyth-ton-js";

const BTC_PRICE_FEED_ID =
  "0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43";

async function main() {
  // Initialize TonClient
  const client = new TonClient({
    endpoint: "https://testnet.toncenter.com/api/v2/jsonRPC",
    apiKey: "your-api-key-here", // Get your TON Center API key via @tonapibot or https://t.me/toncenter (optional)
  });

  // Create PythContract instance
  const contractAddress = Address.parse(PYTH_CONTRACT_ADDRESS_TESTNET);
  const contract = client.open(PythContract.createFromAddress(contractAddress));

  // Get current guardian set index
  const guardianSetIndex = await contract.getCurrentGuardianSetIndex();
  console.log("Guardian Set Index:", guardianSetIndex);

  // Get BTC price from TON contract
  const price = await contract.getPriceUnsafe(BTC_PRICE_FEED_ID);
  console.log("BTC Price from TON contract:", price);

  // Fetch latest price updates from Hermes
  const hermesEndpoint = "https://hermes.pyth.network";
  const hermesClient = new HermesClient(hermesEndpoint);
  const priceIds = [BTC_PRICE_FEED_ID];
  const latestPriceUpdates = await hermesClient.getLatestPriceUpdates(
    priceIds,
    { encoding: "hex" }
  );
  console.log("Hermes BTC price:", latestPriceUpdates.parsed?.[0].price);

  // Prepare update data
  const updateData = Buffer.from(latestPriceUpdates.binary.data[0], "hex");
  console.log("Update data:", updateData);

  // Get update fee
  const updateFee = await contract.getUpdateFee(updateData);
  console.log("Update fee:", updateFee);
  const totalFee =
    calculateUpdatePriceFeedsFee(BigInt(updateFee)) + BigInt(updateFee);

  // Update price feeds
  const mnemonic = "your mnemonic here";
  const key = await mnemonicToPrivateKey(mnemonic.split(" "));
  const wallet = WalletContractV4.create({
    publicKey: key.publicKey,
    workchain: 0,
  });

  const provider = client.open(wallet);
  await contract.sendUpdatePriceFeeds(
    provider.sender(key.secretKey),
    updateData,
    totalFee
  );

  console.log("Price feeds updated successfully.");
}

main().catch(console.error);

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On-chain data verification

TODO This code snippet does the following:
  1. Initializes a TonClient and creates a PythContract instance.
  2. Retrieves the current guardian set index and BTC price from the TON contract.
  3. Fetches the latest price updates from Hermes.
  4. Prepares the update data and calculates the update fee.
  5. Updates the price feeds on the TON contract.

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Additional resources

You may find these additional resources helpful for developing your TON application:
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