[Ethereum] How to read “allevents” using Python web3 (there’s capability in web3.js)

contract-developmenteventspython

Is there a mechanism to create a listener for all events being emitted from a smart contract for the python web3 library. There is a way to do it in web3.js:

myContract.events.allEvents([options][, callback])

However, I don't see a parallel in Python's library. There is a function to get all of the events in Hex but I am looking for the human readable version.

How to get events in Hex:

event_filter = web3.eth.filter({"address": contract_address})

web3.js documentation: https://web3js.readthedocs.io/en/1.0/web3-eth-contract.html#events-allevents
web3.py documentation: http://web3py.readthedocs.io/en/stable/filters.html

Best Answer

One option is to iterate all events and call createFilter on each of the events. Something like:

from web3.contract import ContractEvent

filters = [
  event.createFilter(fromBlock='latest')
  for event in myContract.events
  if issubclass(event, ContractEvent)
]

Related Solutions

[Ethereum] Proper way of using allEvents()

Turned out I shouldn't have used the callback in this case. Here's the working code:

let events = token.allEvents({fromBlock: creationBlock, toBlock: 'latest'});
events.get((error, events) => {
    if (error)
        console.log('Error getting events: ' + error);
    else
        return res.json(events);
});

[Ethereum] web3 python sendTransaction error

The etherscan API is not a JSON-RPC-compatible API. If you want to use a remote node with web3, you can use something like Infura.

According to their documentation, there are ways to invoke the JSON-RPC methods, but they don't actually implement the API externally. For example, to get the latest block number in the JSON-RPC API, you would send a POST like this:

curl -X POST --data '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":83}' localhost:8545

(which web3.py does for you behind the scenes of w3.eth.blockNumber)

In the etherscan API, you would send a GET, like this:

curl https://api.etherscan.io/api?module=proxy&action=eth_blockNumber&apikey=YourApiKeyToken

The two APIs are simply different. It would be possible to create a new specialized EtherscanProvider to work inside web3.py, instead of the normal HTTPProvider, but it would take a bit of work.

Best Answer

Related Solutions

[Ethereum] Proper way of using allEvents()

[Ethereum] web3 python sendTransaction error

Related Topic