Metamask: How to parse json rpc errors on the front end?

Parsing JSON RPC Errors and Extracting Recovery Messages in JavaScript

JSON RPC (JavaScript Object Request Processing) is the standard way for JavaScript to communicate with smart contracts over the Ethereum network. When a transaction fails, an error message can be returned that developers need to analyze and understand.

In this article, we’ll show you how to parse JSON RPC errors in the UI to extract recovery messages in the event that a failed transaction returns an error.

Why Parse JSON RPC Errors?

JSON RPC provides a number of benefits for interacting with smart contracts:

• Error Handling: JSON RPC allows for explicit error handling, making your application more robust and reliable.

• Transaction Recovery Messages

  : By parsing the error message returned by the contract, you can extract the underlying transaction recovery message that may be required to recover from a failed transaction.

Parsing JSON RPC Errors

To parse JSON RPC errors in the UI, you need to follow these steps:

• Get the contract methods and events

  

  : First, you need to get the methods and events defined in the contract.

• Call a function with the error message: Then, call a function that takes the error message as input. This will help you parse the error data and extract any relevant information.

• Parse the JSON data: Finally, parse the JSON data returned by the call function to extract any useful information.

Here is some sample code to help you get started:

const Web3 = require('web3');
const contractAbi = [...]; // Contract ABI
asynchronous function parseError(error) {
try {
const methodsAndEvents = await this.contract.methods.getMethods();
for (const method methodsAndEvents) {
if (method.name === 'someMethod') {
const params = await method.params;
let revertMessage;
if (param length > 0) {
// Check if the error is related to a specific parameter
const paramKey = parameters[0];
for (const param of params.slice(1)) {
if (param.key === 'revert') {
revertMessage = JSON.parse(param.value);
break;
}
}
}
if (revertMessage) {
return revertMessage;
} else {
// No return message found, return empty string
return '';
}
}
}
} catch (error) {
console.error('Error parsing error:', error);
}
}

How ​​to use

To use this code in the UI, you need to do the following:

• Replace contractAbi with your contract ABI.

• Set up a Web3 instance and connect it to your Ethereum network.

• Call parseError when an error occurs in a transaction or method call.

Here is an example of using this code in a simple React application:

“javascript

// CallsomeMethodfunction with error message as input

console.log(Revert message: ${JSON.parse(error.message).revertMessage}`);

} else {

console.