Package Exports

@harmony-js/contract
@harmony-js/contract/dist/index.esm.js
@harmony-js/contract/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@harmony-js/contract) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

@harmony-js/contract

This package provides a collection of apis to create, deploy, and interact with smart contracts. In Harmony, smart contracts all fully EVM compatible and the formats and terminologies match 1-to-1 with EVM smart contracts.

Installation

npm install @harmony-js/contract

Usage

Deploying a contract using contractConstructor

const { ContractFactory } = require('@harmony-js/contract');
const { Wallet } = require('@harmony-js/account');
const { Messenger, HttpProvider } = require('@harmony-js/network');
const { ChainID, ChainType, hexToNumber } = require('@harmony-js/utils');

const wallet = new Wallet(
  new Messenger(
    new HttpProvider('https://api.s0.b.hmny.io'),
    ChainType.Harmony,
    ChainID.HmyTestnet,
  ),
);
const factory = new ContractFactory(wallet);

const contractJson = require("./Counter.json");
const contract = factory.createContract(contractJson.abi);

const options1 = { gasPrice: '0x3B9ACA00' }; // gas price in hex corresponds to 1 Gwei or 1000000000
let options2 = { gasPrice: 1000000000, gasLimit: 21000 }; // setting the default gas limit, but changing later based on estimate gas

const options3 = { data: contractJson.bytecode }; // contractConstructor needs contract bytecode to deploy

contract.wallet.addByPrivateKey('1f054c21a0f57ebc402c00e14bd1707ddf45542d4ed9989933dbefc4ea96ca68');

contract.methods.contractConstructor(options3).estimateGas(options1).then(gas => {
  options2 = {...options2, gasLimit: hexToNumber(gas)};
  contract.methods.contractConstructor(options3).send(options2).then(response => {
    console.log('contract deployed at ' + response.transaction.receipt.contractAddress);
  });
});

Instead of contract.methods.contractConstructor, contract.deploy could be used and it will work.

Loading a contract object using the contract json and contract address for interacting with it

const { Harmony } = require("@harmony-js/core");
const { ChainID, ChainType } = require("@harmony-js/utils");
const hmy = new Harmony("https://api.s0.b.hmny.io", {
  chainType: ChainType.Harmony,
  chainId: ChainID.HmyTestnet,
});

const contractJson = require("./Counter.json");
const contractAddr = "0x19f64050e6b2d376e52AC426E366c49EEb0724B1";

const contract = hmy.contracts.createContract(contractJson.abi, contractAddr);
console.log(contract.methods);

Directly loading contract using ContractFactory

const { ContractFactory } = require('@harmony-js/contract');
const { Wallet } = require('@harmony-js/account');
const { Messenger, HttpProvider } = require('@harmony-js/network');
const { ChainID, ChainType, hexToNumber } = require('@harmony-js/utils');

const wallet = new Wallet(new Messenger(
  new HttpProvider('https://api.s0.b.hmny.io'),
  ChainType.Harmony,
  ChainID.HmyTestnet,
));
const factory = new ContractFactory(wallet);
const contract = factory.createContract(contractJson.abi, contractAddr);

Estimate gas for contract methods

const options1 = { gasPrice: '0x3B9ACA00' }; // gas price in hex corresponds to 1 Gwei or 1000000000

contract.methods.getCount().estimateGas(options1).then(gas => {
  console.log('gas required for getCount is ' + hexToNumber(gas));
});

Call contract read-only methods. Harmony uses 1 Gwei gas price and gas limit of 21000 by default. Use the estimate gas api to correctly set the gas limit.

const options1 = { gasPrice: '0x3B9ACA00' }; // gas price in hex corresponds to 1 Gwei or 1000000000
let options2 = { gasPrice: 1000000000, gasLimit: 21000 }; // setting the default gas limit, but changing later based on estimate gas

contract.methods.getCount().estimateGas(options1).then(gas => {
  options2 = {...options2, gasLimit: hexToNumber(gas)};
  contract.methods.getCount().call(options2).then(count => {
    console.log('counter value: ' + count);
  });
});

Invoking contract modification methods using send api. Need to add a signing account to the contract wallet, otherwise send api will not work.

const options1 = { gasPrice: '0x3B9ACA00' }; // gas price in hex corresponds to 1 Gwei or 1000000000
let options2 = { gasPrice: 1000000000, gasLimit: 21000 }; // setting the default gas limit, but changing later based on estimate gas

contract.wallet.addByPrivateKey('1f054c21a0f57ebc402c00e14bd1707ddf45542d4ed9989933dbefc4ea96ca68');

contract.methods.incrementCounter().estimateGas(options1).then(gas => {
  options2 = {...options2, gasLimit: hexToNumber(gas)};
  contract.methods.incrementCounter().send(options2).then(response => {
    console.log(response.transaction.receipt);
  });
});

All the above apis can also be asynchronously executed using async and await.

Subscribing to the contract events requires web socket based messenger.

const { ContractFactory } = require('@harmony-js/contract');
const { Wallet } = require('@harmony-js/account');
const { Messenger, WSProvider } = require('@harmony-js/network');
const { ChainID, ChainType, hexToNumber } = require('@harmony-js/utils');
const ws = new WSProvider('wss://ws.s0.b.hmny.io');

const wallet = new Wallet(
  new Messenger(
    ws,
    ChainType.Harmony,
    ChainID.HmyTestnet,
  ),
);
const factory = new ContractFactory(wallet);

const contractJson = require("./Counter.json");
const contractAddr = '0x8ada52172abda19b9838eb00498a40952be6a019';

const contract = factory.createContract(contractJson.abi, contractAddr);

contract.events
  .IncrementedBy()
  .on('data', (event) => {
    console.log(event);
  })
  .on('error', console.error);