Questions tagged [events]
Solidity events and logging problems. Events allow the convenient usage of the EVM logging facilities, which in turn can be used to “call” JavaScript callbacks in the user interface of a dapp, which listen for these events.
162
questions with no upvoted or accepted answers
0
votes
0answers
46 views
Timeout when try to connect over websocket in web3.py
I am trying to listen for events emitted by a simple Solidity contract. I am not able to connect using ws though I can commit transactions using http.
Here's my code for event listening -
import ...
0
votes
0answers
17 views
How unique are the event log ids?
I am using log_ids of events to keep track of which events I've processed.
Log ids are formed using the word log followed by 8 hexadecimal characters i.e. log_d758eda8
The possible combinations of ...
0
votes
1answer
49 views
Unable to filter events with specific values of indexed parameters
I am currently trying to test a smart contract using the truffle suit ( with 'truffle test'). My contract is of a simple ERC20 token which includes the standard Transfer event:
event Transfer(address ...
0
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0answers
107 views
Efficient way to save and retrieve hash in blockchain
I am learning Ethereum using Geth. I have a private blockchain and I am saving hashes through a REST API (python web service). I have readed I can save hash values using maps (mapping data type) and ...
0
votes
1answer
34 views
Storing name values off-chain in events and web3.js
Somewhere I read the advice to store name (title, geographical name, people name, etc.) value off-chain in events.
But if a value is stored in an event, is there an efficient way to retrieve its ...
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0answers
19 views
How to filter ERC721 events?
I got inspired by cryptozombies to start working with ERC721 and give them a try.
Now that I have my collectable idea set up, I want to allow people doing exchanges but for erc20s. Notice that this ...
0
votes
0answers
16 views
0x event extra data fields
I'm looking at events on the exchange contract address: https://etherscan.io/address/0x61935cbdd02287b511119ddb11aeb42f1593b7ef#events with a topic_0 equal to ...
0
votes
1answer
20 views
Event propagation from imported contracts
Im implementing a contract with imported subcontracts of my own. I'm trying to understand if I can receive the events emitted by the imported contracts, but since contracts can be inherit other ones ...
0
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0answers
8 views
Nethreum CreateFilterInput Block Number boundary issue
I obtained the latest block number by using:
var Latest = web3.Eth.Blocks.GetBlockNumber.SendRequestAsync().Result;
Assume Latest = 400000
I create a filter even from block number 390000 to (the ...
0
votes
1answer
264 views
Web3js - Internal Transaction Data (Event Logs): Token Transfers, Contract Creations, & Internal ETH Transfers
I'm currently recording transaction data via Web3js, while directly connected to a local Geth full archive node via IPC, and I was wondering if there was a more elegant way to record internal ...
0
votes
1answer
99 views
getPastEvents on localhost is not a function error
Now, I'm working on an Ethereum Blockchain project to transfer the ownership of stored devices by using local web3 provider at the truffle environment.
Truffle v5.0.27 (core: 5.0.27)
Solidity v0.5....
0
votes
1answer
66 views
Smart Contract Transfer Event Log Data & transfer _value [Rust]
I'd like to have a better understanding of events and logs data, more specifically when it comes to interacting with ERC20 tokens smart contracts and their Transfer events.
I'm looking for a way to ...
0
votes
0answers
52 views
getPastEvents undefined(please help)
I had asked this question before. I looked carefully at the exchange section, which I advised, and I think there is no problem with the exchange section. At least in my opinion there is no problem and ...
0
votes
0answers
98 views
Events using Infura websockets on rinkeby Web3 1.2.1. Returned values aren't valid, did it run Out of Gas?
I am trying to do a simple event listener with NodeJS and Web3 using an Infura endpoint. I have the correct project-id
const Web3 = require('web3');
let web3 = new Web3(
// Replace YOUR-PROJECT-ID ...
0
votes
0answers
50 views
Error: invalid number/address values
Having trouble with the submitOracleResponse inside the callback below:
flightSuretyApp.events.OracleRequest({
fromBlock: 0
}, function (error, event) {
if (error) console.log(error);
...
0
votes
0answers
35 views
Problem accessing variables stored in event log
I have succesfully implemented an event in my contract Portfolio:
// Define eventlog for myEvent
event myEvent(uint indexed eventDate, address indexed sender, myArray[] eventList, uint eventBalance);
...
0
votes
0answers
17 views
Listening events
I have a problem I want to solve with watchevent function.
I am building a daemon script that submit a transaction when a particular event is emitted. Let's suppose the node that run the script goes ...
0
votes
0answers
70 views
Getting empty events in response of receipt. I am using Infura+web3.js+ropsten
JS code
contract.methods
.myFunction(
"data1",
1568545262,
1568631662,
1568718062,
"0xD4496dA2a4b376fC8s4d786EB6B71483436077c4"
)
.send({
from: "...
0
votes
0answers
39 views
web3 update monitoring
Inside a DAPP, I have been using
web3.currentProvider.publicConfigStore.on('update',...
to monitoring Metamask activity.
But in the new metamask-mobile such method does not exists.
There is a ...
0
votes
1answer
358 views
Filters object not working for web3.eth.contract getPastEvents() method
I have referred, Web3 Events, but filters object is not working for me, I've got the same result for events before and after applying filter object.
Here's the code:
instance.getPastEvents(
"...
0
votes
0answers
41 views
How to filter by string parameter , web3 2.0.0-alpha.1 Solidity events?
I'm trying to filter some events , and I noticed since I updated the web3 to version 2.0.0-alpha 1 the event catch is a little bit different.
I have a Smart Contract with this event :
event ...
0
votes
0answers
46 views
No Events After Deploying Another Contract in Remix
I am trying to write an upgradable smart contract in Remix. This involves a Proxy contract, a Logic_0_1_0 contract, and a Logic_0_2_0 contract.
I uploaded Proxy and Logic_0_1_0 only, and the ...
0
votes
1answer
65 views
Solidity Events
I'm using Solidity events to interact with my html page, once a change is done in the contract or page the watch function from html reflects back to the contract.
My question here is, while checking ...
0
votes
0answers
51 views
Web3.js doesn't fire event callbacks anymore
I have a small dapp that uses web3.js to interact with a contract. I have one event listener:
let activateEvent = nexusContract.events.Activate({ _member: defaultAccount })
activateEvent.watch((...
0
votes
1answer
47 views
Web3 event listener - timing issue when immediately retrieving contract values
I'd like to be able to immediately get a struct value from a mapping after calling a function that updates the struct, however, when testing with Ganache, sometimes the event arrives to the listener ...
0
votes
1answer
143 views
In node.js event is not fired
I am using web socket to get event. sending transaction works fine. but event is not fired.
also I referred Web3 events not working
but it does not work, too.
I used eventemitter also. but it did ...
0
votes
0answers
298 views
Can I subscribe to events emitted by another contract?
I am trying to subscribe to an event emitted by an existing library's smart contract. I've found examples of how to subscribe to events emitted by my contract using web sockets and my contract ABI as ...
0
votes
1answer
151 views
Viewing transaction events by using web3 on geth console
According to https://web3py.readthedocs.io/en/stable/contracts.html#web3.contract.ContractEvents.myEvent
web3 allows to extract the pertinent logs from a transaction receipt:
tx_hash = contract....
asked May 6 '19 at 16:06
Juan Ignacio Pérez Sacristán
2,7633 gold badges27 silver badges60 bronze badges
0
votes
1answer
273 views
How to listen contract event in Python
The test contract is
pragma solidity ^0.5.0;
contract Test{
event Here(uint256 indexed a);
uint256 public a;
function add() public returns (uint256){
a += 1;
emit Here(...
0
votes
2answers
36 views
Can events always be called directly by user accounts? Is there a way to make them internal?
I am using events to fire an order, basically using them as a vehicle for a master/slave connection with an IoT device, through the blockchain.
Ideally i want to always verify the right msg.sender is ...
0
votes
1answer
39 views
Mapping or indexed event
I want to store data on chain that is not needed within a smart contract but should be retrieved easily and particularly quickly from outside. I know that storing the data within an indexed event is ...
0
votes
1answer
47 views
getting the latest holders address:balance for a smart contract
I managed to get all the transfer events from any given smart contract, but now I need to reduce that to current holder any idea how I would do this?
Here is my code so far:
import ERC20ABI from './...
0
votes
1answer
47 views
Truffle Exec Return Events
I have set up a JavaScript file that takes in my contract and executes the various functions and then returns the correct events. The file runs through 'truffle exec'.
I am using the following line ...
0
votes
1answer
320 views
Web3.js event.get not firing, whereas event.watch gives correct values
I am trying to do a simple test for events.
Following is solidity code.
Values received from chgEvent.watch are always correct.
But in chgEvent.get, results1 is empty. chgEvent.get does not get ...
0
votes
2answers
264 views
Solidity event function not appearing in web3
I have a contract with the following event (using 0.4.24):
event UpdateProgress(bool _gameInProgress);
I am registering the contract like this:
import Web3 from 'web3';
import address from './...
0
votes
2answers
50 views
Subscribing to multiple Transfer events of various ERC20s
I need to suscribe to Transfer events of couple of different ERC20s in order to catch transfers to my contract. And here is the question: to catch all those events I need to create instance of each ...
0
votes
1answer
52 views
Problem watching events without invoke functions in the Smart Contract
I have an event which is sent each time when a contract is deployed. It is launched in the constructor.
I have a Dapp where I want to watch this event to send a tx each time that a smart contract is ...
0
votes
0answers
41 views
How to read ALL logs of a certain event
When I read event logs like this:
myContract.getPastEvents('myEventLogName', {
fromBlock: 0,
toBlock: 'latest'
})
.then(function(events){
console.log(events) // same results as the ...
0
votes
1answer
732 views
Proper way of using allEvents()
I'm trying to get all events for a contract:
let events = token.allEvents({fromBlock: creationBlock, toBlock: 'latest'}, (err, res) => {
try {
let result = events.get();
...
0
votes
0answers
69 views
can't read past event logs
const event = contractInst.Transfer({},{fromBlock: 0, toBlock: 'latest'});
events.get(function (error, result) {
if (!error) {
console.log(result);
}
});
The get ...
0
votes
1answer
471 views
How to get only past 2 days events using getPastEvents everytime?
How can the following query be modified to only fetch the past two days worth of events:
const events= await MyContract.getPastEvents("eventName", {
fromBlock: 0,
toBlock: "latest"
});
0
votes
0answers
247 views
Listen to filtered events using web3js 0.19 (provided by infura)
I am working on a uport dApp. uPort by default uses web3 from rinkeby.infura.io which is web3 version 0.19. So no WebSocket available. I tried ZeroClientProvider but that leads to this error:
Error ...
0
votes
0answers
50 views
Events firing but bool variable not changing in value
Given a contract with an event as follows
contract test {
event LogEvent(
address a,
bool result
);
function testInputs(some parameters) public (){
....
...
0
votes
0answers
151 views
Unable to catch contract event using parity websockets
I have a contract deployed on ropsten which emits event when ether amount is deposited in it. I can see the event appearing in etherscan.
this.web3Socket = new Web3(new Web3.providers....
0
votes
0answers
90 views
When exactly do events fire
I have a web3J application that is supposed to deploy a contract (by calling a function on another contract) then listen for the contractCreatedEvent that is fired by the factoryContract and then call ...
0
votes
1answer
1k views
How to use events to retrieve data from a transaction? PRIVATE CHAIN
i am using GETH for the architecture and deployment of my contract on a private chain and it works pretty fine, but unfortunately i want to return data from a transaction function and this makes me ...
0
votes
1answer
365 views
Why myContract.events.MyEvent([options][, callback]) does not return “data” and “logs”?
We have an event as follows :
event LogNewObject(address sender, bytes32 indexed id, bytes32 sub_states_types, bytes32 sub_states_values, address owner);
This event is called in following function :
...
0
votes
1answer
61 views
A common error at time of using web3 options
When i use some web3 options as follows, I receive a common error i.e.
TypeError: web3.[option] is not a function
For example :
TypeError: web3.toAscii is not a function
web3.toAscii(...
0
votes
0answers
777 views
Truffle Test Sell Event Assertion Error
When I test my selling event in truffle.So, the following error comes:-
The solidity code is :-
event Sell(address _buyer, uint256 _amount);
// Buy token
function buyTokens(uint256 _numberOfTokens) ...
0
votes
2answers
585 views
How to find the block, when contract was deployed
I have contract address, and I want to find the block number, when it was deployed, to use it for loading events for this contract. Is it possible?
