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Ethereum: Polygon zk-EVM Get Token Balance Error
Overview
The Ethereum Virtual Machine (EVM) and Zk-SNARKs (zk-Edward Key-Share Proofs) are powerful tools for building secure and scalable decentralized applications (dApps). However, integrating these concepts with the Ethereum blockchain can be challenging due to their different architectures. In this article, we will explore why you are encountering an error when trying to get the balance of each ERC-20 token in the Polygon zk-EVM network using Ethers.js.
Problem
When working with ERC-20 tokens on the Polygon zk-EVM network, you are encountering the error “Unable to decode result data”. This error occurs because the ethers.js library cannot parse the result of the getBalance() function call used to retrieve the balance of the ERC-20 token.
Problem
The problem stems from the fact that the getBalance() function returns a JSON object containing balance information. However, Ethers.js expects this object to be in a certain format, where it can successfully decode and parse the result. Unfortunately, the ethers.js library cannot process the generated JSON data due to its internal implementation.
Solution
To solve this problem, you have several options:
1. Update Ethers.js to version 5.x
The simplest solution is to update Ethers.js to version 5.x or later, which includes improved support for ERC-20 token states on the zk-EVM network.
npm install ethers@latest
2. Use the ethers.js getBalance() function with a custom decode function
Another solution is to create a custom decode function that can process the resulting JSON data from the getBalance() function call.
Here is an example implementation:
const { ethers } = require('ethers');
asynchronous function getBalance(tokenAddress) {
const balance = await ethers.getBalance(tokenAddress);
return new Promise((resolve, discard) => {
try {
resolve(balance.data.toString());
} catch (error) {
reject (error);
}
});
}
getBalance("0x...").then((balance) => {
console.log(balance); // Output: balance data as a string
}).catch((error) => {
console.error(error);
});
In this example, we define a custom getBalance() function that takes a token address and returns a promise that resolves the balance data as a string. This allows us to successfully process the received JSON data.
Conclusion
By updating Ethers.js to version 5.x or creating a custom decode function, you should be able to resolve the “unable to decode result data” error when getting the state of each ERC-20 token in the Polygon zk-EVM network using Ethers.js.