@hovoh/ethcall

ethcall

Utility library to make calls to Ethereum blockchain.

Uses MakerDAO's Multicall contracts to make multiple requests in a single HTTP query. Encodes and decodes data automatically.

Powered by abi-coder and ethers.js.

npm install ethcall

API

• Contract
  • constructor(address, abi): creates Contract instance
  • CALL_FUNC_NAME: yields a call object; usage is similar to ethers Contract class
• Provider
  • constructor(): creates Provider instance
  • init(ethersProvider): initializes a provider; should be called once before any other request
  • all(calls): executes all calls in a single request
  • tryAll(calls): executes all calls in a single request. Ignores reverted calls and returns null value in place of return data (wrapper on top of tryAggregate method)
  • tryEach(calls, canFail): executes all calls in a single request. Ignores reverted calls and returns null value in place of return data for the calls that are allowed to fail (wrapper on top of aggregate3 method)
  • getEthBalance(address): returns account ether balance

Example

Also see examples for reference.

import { InfuraProvider } from '@ethersproject/providers';
import { Contract, Provider } from 'ethcall';

import erc20Abi from './abi/erc20.json';

const infuraKey = 'INSERT_YOUR_KEY_HERE';
const provider = new InfuraProvider('mainnet', infuraKey);

const daiAddress = '0x6b175474e89094c44da98b954eedeac495271d0f';

async function call() {
  const ethcallProvider = new Provider();
  await ethcallProvider.init(provider);

  const daiContract = new Contract(daiAddress, erc20Abi);

  const uniswapDaiPool = '0x2a1530c4c41db0b0b2bb646cb5eb1a67b7158667';

  const ethBalanceCall = ethcallProvider.getEthBalance(uniswapDaiPool);
  const daiBalanceCall = daiContract.balanceOf(uniswapDaiPool);

  const data = await ethcallProvider.all([ethBalanceCall, daiBalanceCall]);

  const ethBalance = data[0];
  const daiBalance = data[1];

  console.log('eth balance', ethBalance.toString());
  console.log('dai balance', daiBalance.toString());
}

call();

Contributing

All Mulitcall contracts are stored in src/multicall.ts file. There are three getMulticall methods corresponding to three Multicall versions. To add a new contract, you need to know its version, address, chain id of the underlying chain, and (optionally) block at which the Multicall contract was deployed.

Deployless Multicall

If you query a chain on which Multicall is not deployed, or if you query a historical block before the deployment of the contract, the deployless version will be used instead. In short, deployless Multicall "emulates" the deployed contract and returns the exact same data. Note that you can't query ETH balance using deployless version.

You can read more about deployless Multicall here.