Ethereum: Integrating ERC20 pre-transaction validation using Wagmi in the interface

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Ethereum: Integrating ERC20 pre-transaction approval with Wagmi on the frontend

When building decentralized applications (Dapps) on the Ethereum blockchain, a common challenge is handling token transfers between users. An important aspect of this process is ensuring that the user has approved the smart contract before transferring their tokens.

In our Dapp, we use ERC-20 tokens for various purposes, including payment processing and storage. However, requiring users to approve a smart contract to transfer these tokens can be cumbersome and lead to unnecessary delays or errors. This is where Wagmi comes in – an efficient and user-friendly library that simplifies the interaction with the Ethereum blockchain.

In this article, we explore how to integrate ERC20 pre-transaction approval with Wagmi on the frontend of our Dapp.

Why Wagmi?

Wagmi is a popular, modern Web3 library that provides a simple and intuitive way to interact with the Ethereum blockchain. Core features include:

• Automatic token transfers: Wagmi handles the complex logic required for automatic token transfers, making it easier for us to focus on developing our Dapp.

• Simple API calls

  : Wagmi’s API is designed for ease of use, allowing developers to leverage its features without requiring extensive knowledge of Ethereum programming.

• Error handling and retry mechanisms: Wagmi provides robust error handling and retry mechanisms to ensure our application remains stable and efficient.

Integrate ERC20 approval into Wagmi

To integrate ERC20 approval before transacting with Wagmi in the frontend of our Dapp, we will follow these steps:

• Install Wagmi: First, install Wagmi by running “npm install wagmi” or “yarn add wagmi” in your project directory.

• Import Wagmi: We import Wagmi and its dependencies into our application:

import { useWagmi } from 'wagmi';

• Create a provider: Next, we create a provider instance to interact with the Ethereum blockchain:

const Provider = {
...useWagmi({
// Specify the provider chain (e.g. '
network: 'eth',
}),
};

• Define the token transfer function: Now we define a custom function to handle token transfers using Wagmi:

const handleTokenTransfer = async({ data, params }) => {
// Extract the ERC-20 token address and amount from the parameters
const tokenAddress = params.tokenAddress;
const amount = params.amount;
// Use Wagmi to transfer the tokens automatically
return await Provider.useMutation(
'transfer',
{
// Provide the transaction details including the token contract address, sender's wallet address and receiver's wallet address
inputs: { from: params.fromAddress, to: tokenAddress, amount },
}
);
};

• Call the custom function when a user tries to send tokens: We add a check to make sure the user has approved the smart contract before transferring their tokens:

“`javascript

const handleTokenTransferRequest = async(event) => {

// Check if the user has approved the smart contract for token transfer

const result = await Provider.query({

query: {

inputs: {

fromAddress,

toAddress,

amount,

network: ‘eth’,

tx: { jsonrpc: ‘2.0’ },

},

},

});

// If approved, proceed with token transfer using Wagmi

if (result.data.approval) {

await handleTokenTransfer({ data: result.data, params: event });

} else {

// Handle the case where the user has not approved the smart contract

Console.

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