Web3.js Guide – How to Get Pending and Failed Transactions

web3js

I want my front end to show the status of my solidity functions. When my functions are successful I fire a "success" event. I can watch for that event and respond to it like so:

const events = myContract.allEvents({ fromBlock: 0, toBlock: 'latest' })
      events.watch( (err, evt) => {}

However, I would also like to display when these functions are pending and when they have failed, but I cant figure out how.

I notice that when I do this:

await web3.eth.filter("pending").watch(
      function(error,result){
          if (!error) {
              console.log("pending" + result);
          }
      }
    )

I can see various transactions as they are pending, but I'm not sure how to tell if one of them corresponds to one of the functions I care about.

I'm not even sure how I would figure out if a transaction has failed.

Any help would be great thanks!

Best Answer

I can see various transactions as they are pending, but I'm not sure how to tell if one of them corresponds to one of the functions I care about.

After you make a transaction, web3 gives you a transaction hash. This uniquely identifies the transaction.

I'm not even sure how I would figure out if a transaction has failed.

You use eth.getTransactionReceipt(transactionHash) (after transaction is mined) and check the status field. A status of 1 denotes success, whereas 0 denotes failure.

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The answer is

status: false

This indicates what you see on etherscan. If you try getting this field through web3, the response is usually 0x0 or 0x1.

So here you go:

web3.eth.getTransactionReceipt(txID, function (e, data) {
            if (e !== null) {
                console.log("Could not find a transaction for your id! ID you provided was " + txID);
            } else {
                console.log(data);
                if(data.status == '0x0') {
                    console.log("The contract execution was not successful, check your transaction !");
                } else {
                    console.log("Execution worked fine!");
                }

[Ethereum] ERC20 tokens transactions’ history from Ethereum node

using ethersjs. This will return all transfer logs for all tokens on the network.

Under the hood it takes the signature from the event out of the ABI , which is the first element needed in the topics array (the remaining optional arguments are the indexed arguments from the event)

It then makes an RPC call for these events to the node you supplied when creating the provider.

On succesful response it parses the received hex-encoded data back to human readable data through reading the types from the ABI.

const provider = new providers.JsonRpcProvider('http...')
const event = (new Interface(StandardToken.abi)).events.Transfer
const topics = [event.topics[0]]
let logs = await provider.getLogs({
  fromBlock: 1,
  toBlock: 'latest',
  topics: topics
})

logs =  logs.map(log => event.parse(log.topics, log.data))

Best Answer

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