mantle-tutorial

View transactions between layers

This tutorial teaches you how to use the Mantleio SDK to view the transactions passed between L1 and L2 by an address.

Prerequisites

The node script makes these assumptions:

1. You have Node.js running on your computer, as well as yarn.
2. Access to L1 and L2 providers.

Running the script

1. Use yarn to download the packages the script needs.

   yarn
   

2. Use Node to run the script

   yarn script
   

Results

Here are the expected results. Note that by the time you read this there might be additional transactions reported.

Deposits by address 0x23618e81E3f5cdF7f54C3d65f7FBc0aBf5B21E8f
tx:0x3979f14c8e890aec790fa3743c2d7ae736b48aebfc9dc990e84b77cfaf744525
        Amount: 1 L1EPT
        Relayed: true

Withdrawals by address 0x23618e81E3f5cdF7f54C3d65f7FBc0aBf5B21E8f
tx:0xe650064362f163a394d3123e20029ed1b03846a6ae62e4cc8e962482c9cd4814
        Amount: 1 L1EPT
        Relayed: false

How does it work?

In this section we go over the script line by line to learn how to use the SDK to view deposits and withdrawals.

#! /usr/local/bin/node

const ethers = require("ethers")
const mantleSDK = require("@mantleio/sdk")

// Global variable because we need them almost everywhere
let crossChainMessenger

const setup = async () => {
  crossChainMessenger = new mantleSDK.CrossChainMessenger({
    l1ChainId: process.env.L1_CHAINID,
    l2ChainId: process.env.L2_CHAINID,
    l1SignerOrProvider: l1Wallet,
    l2SignerOrProvider: l2Wallet
  })
}

Create the CrossChainMessenger object that we use to view information. Note that we do not need signers here, since we are only calling view functions. However, we do need the chainId values.

// Only the part of the ABI we need to get the symbol
const ERC20ABI = [
  {
    "constant": true,
    "inputs": [],
    "name": "symbol",
    "outputs": [
        {
            "name": "",
            "type": "string"
        }
    ],
    "payable": false,
    "stateMutability": "view",
    "type": "function"
  }
]

const getSymbol = async l1Addr => {
  if (l1Addr == '0x0000000000000000000000000000000000000000')
    return "ETH"

If l1Addr is all zeroes, it means the transfer was ETH.

  const l1Contract = new ethers.Contract(l1Addr, ERC20ABI, crossChainMessenger.l1SignerOrProvider)
  return await l1Contract.symbol()  

Otherwise, ask the contract (we could have used the L1 or the L2) what is the correct symbol.

const describeTx = async tx => {
  console.log(`tx:${tx.transactionHash}`)
  // Assume all tokens have decimals = 18
  console.log(`\tAmount: ${tx.amount / 1e18} ${await getSymbol(tx.l1Token)}`)
  console.log(`\tRelayed: ${await crossChainMessenger.getMessageStatus(tx.transactionHash)
    == mantleSDK.MessageStatus.RELAYED}`)
}

The result of crossDomainMessenger.getMessageStatus()is a MessageStatus enumerated value. In this case we only care whether the deposit/withdrawal is still in process or if it is done.

const main = async () => {    
    await setup()
    const deposits = await crossChainMessenger.getDepositsByAddress(l1Wallet.address)

The crossChainMessenger.getDepositsByAddress() function gives us all the deposits by an address.

    console.log(`Deposits by address ${addr}`)
    for (var i=0; i<deposits.length; i++)
      await describeTx(deposits[i])

    const withdrawals = await crossChainMessenger.getWithdrawalsByAddress(l1Wallet.address)

The crossChainMessenger.getWithdrawalsByAddress() function gives us all the deposits by an address.

    console.log(`\n\n\nWithdrawals by address ${addr}`)
    for (var i=0; i<withdrawals.length; i++)
      await describeTx(withdrawals[i])
} 

main().then(() => process.exit(0))
  .catch((error) => {
    console.error(error)
    process.exit(1)
  })

Conclusion

You should now know how to identify all the deposits and/or withdrawals done by a specific address. There are some additional tracing functions in CrossChainMessenger, but they are very similar in operation.