How to read from contracts using ethers?
ethers (opens in a new tab) is one of the prominent standard libraries used for interacting with "web3."
It is widely used, and if you come from a different ecosystem, using ethers might be a more straightforward way to get started rather than interacting with Connex directly.
By combining @vechain/web3-providers-connex (opens in a new tab) (VeChain Connex) with ethers (v5), you can easily create the ability to interact with VeChain contracts.
Setting Up the Provider
ethers requires a provider to understand how to interact with the blockchain and submit standard commands. Below is an example snippet that creates a provider for the VeChain MainNet:
import Connex from "@vechain/connex";
import * as thor from '@vechain/web3-providers-connex'
// Connect to VeChain
const connex = new Connex({
node: "https://node-mainnet.vechain.energy",
network: "main"
});
// Inject VeChain Connex Connectivity into an ethers provider
const provider = thor.ethers.modifyProvider(
new ethers.providers.Web3Provider(
new thor.Provider({ connex })
)
)Setting Up the Contract Interface
A generic contract interface can be configured using an address and its ABI. Here is an example for the VTHO Contract and its totalSupply function:
// configure the VTHO contract like any other contract
const CONTRACT_ADDRESS = '0x0000000000000000000000000000456e65726779'
const ABI = [{
name: "totalSupply",
inputs: [],
outputs: [{ internalType: "uint256", name: "vtho", type: "uint256" }],
stateMutability: "view",
type: "function"
}]The interface is created using ethers.Contract and combines contract information with the provider:
const VTHOContract = new ethers.Contract(CONTRACT_ADDRESS, ABI, provider);Using the Contract Interface
Interacting with the contract is simplified to a single async call that responds with the contract outputs:
const totalSupply = await VTHOContract.totalSupply()