Ethereum: Integrating ERC20 Approval Before Transaction using Wagmi on Frontend

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Ethereum: Integrating ERC20 Approval Before Transaction using Wagmi on Frontend

When building decentralized applications (dapps) on the Ethereum blockchain, one common challenge is handling token transfers between users. One key 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 may lead to unnecessary delays or errors. That’s where Wagmi comes in – an efficient and easy-to-use library that simplifies interacting with the Ethereum blockchain.

In this article, we’ll explore how to integrate ERC20 approval before transaction using 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. Its core features include:

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

• Simple API calls: Wagmi’s API is designed to be easy to 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 that our application remains stable and efficient.

Integrating ERC20 Approval with Wagmi

To integrate ERC20 approval before transaction using Wagmi on the frontend of our dapp, we’ll follow these steps:

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

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

import { useWagmi } from 'wagmi';

• Create a provider: Next, we’ll 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’ll define a custom function to handle token transfers using Wagmi:

const handleTokenTransfer = async ({ data, params }) => {

  // Extract the ERC-20 token's 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',

    {

      // Specify the transaction details, including the token contract address, sender's wallet address, and recipient's wallet address

      inputs: { from: params.fromAddress, to: tokenAddress, amount },

    }

  );

};

• Call the custom function when a user tries to send tokens: We’ll add a check to ensure that 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 approval is granted, proceed with the token transfer using Wagmi

if (result.data.approval) {

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

} else {

// Handle the case where user hasn’t approved the smart contract

console.

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