ethers-multicall
β‘ π Call multiple view functions, from multiple Smart Contracts, in a single RPC query!
Querying an RPC endpoint can be very costly (100+ queries) when loading data from multiple smart contracts. With multicall, batch these queries into a single, on-chain query, without additional over-head!
This is the standalone package of the library formerly created & used by Zapper.
Install
npm install @morpho-labs/ethers-multicall
yarn add @morpho-labs/ethers-multicall
Usage
import { ethers } from "ethers";
import { EthersMulticall } from "@morpho-labs/ethers-multicall";
const provider = new ethers.providers.JsonRpcBatchProvider("...");
const multicall = new EthersMulticall(provider);
const uni = multicall.wrap(
new ethers.Contract("0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984", UniswapAbi)
); // make sure to always wrap contracts to benefit from multicalls
Promise.all([uni.name(), uni.symbol(), uni.decimals()]).then(console.log);
Limitations
- When performing calls in parallel, a single incorrect call may revert and make the aggregated call to the Multicall contract revert ; effectively throwing multiple errors in your code. The following example illustrates this limitation:
const performCall = async (address: string) => {
const erc20 = await multicall.wrap(new ethers.Contract(address, ERC20Abi));
try {
const symbol = await erc20.symbol();
} catch {
return console.error("An error occurred while fetching the symbol of token:", address);
}
};
Promise.all(
[
"0x056Fd409E1d7A124BD7017459dFEa2F387b6d5Cd", // valid GUSD token address
"0x0000000000000000000000000000000000000000", // invalid ERC20 token address
].map(performCall)
);
// prints 2 errors:
// An error occurred while fetching the symbol of token: 0x056Fd409E1d7A124BD7017459dFEa2F387b6d5Cd
// An error occurred while fetching the symbol of token: 0x0000000000000000000000000000000000000000