6. Interact with the contract - Call

Make sure you have installed SwisstronikJS by running npm i @swisstronik/utils

1. Within the scripts folder, create a file called getMessage.js

2. Let's write our getMessage.js script

• Import hardhat and swisstronikJS functions

//Import hardhat and swisstronikJS functions
const hre = require("hardhat");
const { encryptDataField, decryptNodeResponse } = require("@swisstronik/utils");

• Let's use sendShieldedQuery to send a call/query to the blockchain

/**
 * Send a shielded query/call to the Swisstronik blockchain.
 *
 * @param {object} provider - The provider object for making the call.
 * @param {string} destination - The address of the contract to call.
 * @param {string} data - Encoded data for the function call.
 *
 * @returns {Uint8Array} - Encrypted response from the blockchain.
 */
const sendShieldedQuery = async (provider, destination, data) => {
  // Get the RPC link from the network configuration
  const rpclink = hre.network.config.url;

  // Encrypt the call data using the SwisstronikJS function encryptDataField()
  const [encryptedData, usedEncryptedKey] = await encryptDataField(rpclink, data);

  // Execute the call/query using the provider
  const response = await provider.call({
    to: destination,
    data: encryptedData,
  });

  // Decrypt the call result using SwisstronikJS function decryptNodeResponse()
  return await decryptNodeResponse(rpclink, response, usedEncryptedKey);
};

• Write the main script to use sendShieldedQuery function

async function main() {
  // Address of the deployed contract
  const contractAddress = "0xf84Df872D385997aBc28E3f07A2E3cd707c9698a";

  // Get the signer (your account)
  const [signer] = await hre.ethers.getSigners();

  // Construct a contract instance (must match the name of contract)
  const contractFactory = await hre.ethers.getContractFactory("Swisstronik");
  const contract = contractFactory.attach(contractAddress);

  // Send a shielded query to retrieve data from the contract
  const functionName = "getMessage";
  const responseMessage = await sendShieldedQuery(signer.provider, contractAddress, contract.interface.encodeFunctionData(functionName));

  // Decode the Uint8Array response into a readable string
  console.log("Decoded response:", contract.interface.decodeFunctionResult(functionName, responseMessage)[0]);
}

• Add this by hardhat default

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

The final getMessage.js script should look like this:

const hre = require("hardhat");
const { encryptDataField, decryptNodeResponse } = require("@swisstronik/utils");

const sendShieldedQuery = async (provider, destination, data) => {
  const rpclink = hre.network.config.url;
  const [encryptedData, usedEncryptedKey] = await encryptDataField(rpclink, data);
  const response = await provider.call({
    to: destination,
    data: encryptedData,
  });
  return await decryptNodeResponse(rpclink, response, usedEncryptedKey);
};

async function main() {
  const contractAddress = "0xf84Df872D385997aBc28E3f07A2E3cd707c9698a";
  const [signer] = await hre.ethers.getSigners();
  const contractFactory = await hre.ethers.getContractFactory("Swisstronik");
  const contract = contractFactory.attach(contractAddress);
  const functionName = "getMessage";
  const responseMessage = await sendShieldedQuery(signer.provider, contractAddress, contract.interface.encodeFunctionData(functionName));
  console.log("Decoded response:", contract.interface.decodeFunctionResult(functionName, responseMessage)[0]);
}

main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

3. Execute the following command in your terminal to run the script using the Swisstronik network

npx hardhat run scripts/getMessage.js --network swisstronik

4. Upon successful execution, your terminal should display Decoded response: Hello Swisstronik!! or the latest message you've defined in the contract 🎉