Unification of token approval and contract invocation in Ethers.js
When interacting with decentralized applications (dApps) created on the basis of Ethereum, one of the common patterns involves the transfer of tokens to a smart contract. However, this can lead to unnecessary overhead and potential security risks due to the two separate calls required: the token validation and the contract call.
In our current implementation, we make two separate calls:
await token.approve(contractAddress, amount);
— approval of the specified amount of tokens for this contract.
await contract.myFunction();
— call the contract function using approved tokens.
This approach can be cumbersome and error-prone because it requires manual control of the approval process and ensures that only certain functions are called in the contract.
We present a unified challenge: token validation and contract invocation in Ethers.js
To simplify this process and reduce unnecessary overhead, we introduce a new method called approveAndInvoke
. This function will combine the token validation with the contract call into one call.
import { ethers } from 'ethers';
/**
- Combines token approval and contract call into one call.
*
- @param {string} tokenAddress - The address of the token for approval.
- @param {string} contractAddress - The address of the smart contract to call.
- @param {number} amount - Amount of tokens to approve for the contract.
*/
async function approvedAndInvoke(tokenAddress, contractAddress, amount) {
// Get an instance of the supplier
const provider = await ethers.getProvider();
// Approve the token for this contract
const approvedResponse = await provider approved(tokenAddress, contractAddress, amount);
if (!approveResponse) throw new Error('Token approval failed');
// Call the contract function using the approved tokens
try {
await provider.invokeStatic(contractAddress, 'myFunction', { tokens: [amount] });
} catch (error) {
console.error(error); // Approval and call of the token failed
}
}
export default approvedAndInvoke;
Usage Example
import { approvedAndInvoke } from './approveAndInvoke';
// Replace the contract address and amount with your token address
const tokenAddress = '0x...'; // Replace with actual token address
const contractAddress = '0x...'; // Replace with actual contract address
const amount = 10n;
approvedAndInvoke(tokenAddress, contractAddress, amount).then(() => {
console.log('Tokens approved and successfully invoked!');
}).catch((error) => {
console.error(error); // Approval and call of the token failed
});
This approveAndInvoke
function takes the required parameters, approves the specified tokens for the given contract, and invokes the contract function using these approved tokens. This approach reduces the overhead of manually approving tokens and invoking the contract, making it a more convenient and secure way to interact with dApps built on Ethereum.