How to monitor events on an Solidity Smart Contract using hardhat and ethers?

Question

I'd like to monitor events happening on-chain on a specific Smart Contract. I'd like to know every time a Transfer event happens. I tried to write a code with hardhat, but no events if being logged. Here is my code:

  const abi = [
    "event Transfer(address indexed from, address indexed to, uint256 indexed id)"
  ]

  const MyContract = await new hre.ethers.Contract(
    "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    abi,
    hre.ethers.provider
  )

  MyContract.on("Transfer", (from, to, id) => {
    console.log("Transfered:", from, to, id)
  })
  console.log("monitoring...")

I know that there are events occurring in the blockchain, but my code is not tracking them. What am I doing wrong?

Answer 1

filter = {
    address: "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    topics: [
        utils.id("Transfer(address,address,uint256)")
    ]
}
provider.on(filter, (log, event) => {
    // Emitted whenever a token transfer occurs
})

Try updating the function like this and you'll be able to monitor the transfer events provided the provider emit such events.

Answer 2

Alchemy have some great tools for monitoring, and these all come with a free account for limited testing purposes.

If you want to simply monitor transactions, for instance, their SDK allows a eth_getTransactions call, where you can, for example, specify a to address.

There are plenty of tutorials online depending on what you're looking to achieve.

If you come unstuck at some point, post your question and tag me - I'll do what I can to help :D