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.

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1answer
47 views

How does web3 handle new longest chains?

I have a Dapp which subscribes to events using web3. I'm wondering how I can detect that the longest chain has changed or rather how I can make sure the events that I've received are canonical. The ...
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1answer
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How can I turn this into a human readable output? [closed]

I have this buy function but the output gives me a transaction Nr. or whatever this is async function buy() { var a = document.getElementById("amount").value; var accounts= await web3.eth....
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1answer
598 views

How to see event name in etherscan.io transaction event log?

In etherscan.io, I want to be able to see the event name (signature) in the transaction page event log, like here. Currently, I don't see it here. I'll note that the transaction is indeed sent to a ...
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Sending data outside the blockchain

Once a transaction is committed to the blockchain is there a way to let an entity outside the blockchain (i.e. An entity that is not a node in the blockchain) know that a particular transaction has ...
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1answer
49 views

Listen to a solidity event from a smart contract function [duplicate]

I have the following event: event WaitingPlayer2(address indexed player2); Which I call through: function partecipateAsPlayer2(address player2) public{ emit WaitingPlayer2(player2); } Is ...
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158 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 ...
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2answers
33 views

Returning a value from an external function

I have in a contract: function createCourt() external returns (uint256) { uint256 _id = ++nonce; courtOwners[_id] = msg.sender; return _id; } Now, when I try to call ...
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1answer
223 views

Truffle, getPastEvents synchronously

I try to check that a total of 4 events have been emitted by my contract instance. Next code will fail in the assert.equal line since getPastEvents will process the events in a callback and so the ...
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0answers
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How does function getPastEvents works? It's too quick

I'm trying to understand how .getPastEvents function works. When given block range to search is {fromBlock:0, toBlock: 'latest'} it finds my events almost instantaneously. Shouldn't filtering all 7M ...
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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 ...
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What is an Event?

What is an Event? Are they only used in Solidity? How are events defined? How are events initiated? Is there a standard term for an event's invocation (do you say an event "happened", "was called",...
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1answer
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How can I find the result of a function using Events?

Consider the following basic solidity smart contract event BattleResult(string result,uint playerResult, uint enemyResult); mapping(address => uint)playerChoice; function setChoice(...
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2answers
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Is the range of a FilterQuery inclusive up to ToBlock?

I'm looking to use this function: func (ec *Client) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]types.Log, error) but I'm unsure if the range of the FilterQuery is inclusive or ...
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1answer
596 views

Filtering on events of the entire blockchain not possible in testrpc via truffle

A contract I wrote has an event in its constructor. Since I want to find it back in the logs it doesn't seem possible to start listening to the latest block. Because the event is already 'fired' ...
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2answers
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assertEventEmitted from new contract construction call

At present there is no way I can see or is documented to be able to easily use something like this with the truffle framework: So using chai and writing a test to deploy a contract with something ...
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0answers
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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 ...
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1answer
35 views

Garbage in string parameters of events

I have an event defined like this: event Created( address indexed target, string indexed name ); I do emit Created(..., _name); // called function with _name = "comment" which gives ...
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5answers
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How to listen for contract events in JavaScript tests?

I'm trying to trigger events in my solidity contract to output some debug information in my javascript tests. However the events seem to get never caught. That's the relevant contract code: pragma ...
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1answer
228 views

Error trying to get events in web3.py via Infura

I was trying to get all events from my smart contract (in Ropsten) via Infura node. The problem is that I know that Infura does no support creating filters, but I don't know how to get events by ...
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2answers
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Truffle test, logs do not include an emitted event

I am calling a contract function which emits an event in a transaction. This transaction should include the event and is typically visible via: const receipt = await contractInstance.someFunction() ...
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0answers
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How do I get the value from the event to be displayed on the webpage? [duplicate]

I can connect and console.log the event. But can't bring the value to display on the webpage. I don't know what to do. Front-end import React from 'react'; import logo from './logo.svg'; import './...
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1answer
160 views

What data is in 'calldataload'?

I want to parse event logs that are generated by the contract shown below, which assigns different sections of calldataload to the 4 Topics, and the Data section, of the event logs. Topic 0 receives ...
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1answer
55 views

List of ALL Ethereum Contract Events, for ex: Transfer, Mint, etc

A very simple question, yet couldn't find a simple answer. Where can I find a list of all event types such as Transfer, Mint, etc? Is this stored anywhere, for ex: online database or historically ...
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2answers
119 views

dYdX event log signature hash

dYdX has an event called LogDeposit(address indexed accountOwner, uint256 accountNumber, uint256 market, BalanceUpdate update, address from) within their SoloMargin contract. I am trying to get the ...
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1answer
3k views

Current methods to send encrypted messages from contracts

I am trying to understand if there currently exists a method to send a message from a contract to another contract or a private address? What would the Solidity code for this look like? Perhaps events ...
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3answers
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How to get events emitted by a transaction with web3.js

I'm writing a user interface in Javascript and I'm using the web3.js library. I have the transaction hash of a confirmed transaction. I would like to get an array of all events emitted by that ...
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3answers
5k views

How to check events in Truffle Tests?

What's the best way to check that events were fired in a Truffle test?
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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 ...
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1answer
61 views

Event Names not showing up on Etherscan

For some reason Event Names associated with transactions to my contracts aren't being shown in their Event Logs on Etherscan. Worth noting, this event in particular is not indexed. Any thoughts as to ...
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0answers
285 views

Ganache is not showing any events

I have a contract method which emits events but ganache seems not to catch any events. I say this because when I deploy my contract on ropsten the events are being caught fine but only in ganache I ...
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1answer
36 views

TypeError: market.FileViewed is not a function while trying to watch event

I want to watch for fileViewed event and it throws TypeError: market.FileViewed is not a function in marketplace.FileViewed{ ^ My solidity contract: pragma solidity ^0.5.0; contract ...
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0answers
64 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 ...
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1answer
177 views

Iterating through events

I have events (fired some time ago by the contract) containing numbers. I need to load them all, and then to draw a chart. What I do: contract.getInitBlock(function(error, value) { var ...
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0answers
26 views

How a contract on Ropsten (deployed after fork) emit 3/5 events on the shorter chain while same contract on longer chain emits 5/5 of the events

General info: We have a full-node, which broadcast our txs. We have a EventSource contract which contains 5 events types. The eventSource contract deployed only after Istanbul fork. Our node was ...
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0answers
256 views

The sendSignedTransaction function does not activate the on('receipt') event at an appropriate time

console.log(transacting...); web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex')).on('receipt', receipt => { log(receipt); log(`https://ropsten.etherscan.io/tx/${receipt....
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0answers
107 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 ...
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1answer
40 views

Way to create an event?

As soon as a function is called this other function should also be called!! Example: As soon as ether is deposited it should transfer funds into employees wallet. I already have functions deposit() ...
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1answer
44 views

Emited Solidity Events not being watched at frontend truffle contract instance

So, I have been reading through A LOT of pages about events in Solidity and how to interact with them on frontend but I am still pretty new to this and it seems like there have been multiple changes, ...
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1answer
24 views

If for each setter I can get the blockchain state at the moment and make it queryable, will I still need events?

That question came as part of understanding better the role of events in Ethereum. Can the mechanism which index the blockchain state at each setter and makes it queryable for all parties can ...
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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); ...
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1answer
364 views

eth_getLogs only returns logs for last transaction

The following command only returns logs for the last transaction (or block). I'm currently running ganach-cli for the local testnet. There were previous transactions with events but when a new ...
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0answers
138 views

(1) Parity: why does syncing fall behind, (2) Why are events missing events because of (1)

Background: I have multiple parity nodes setup on Digital Ocean and AWS and event watchers attached to these nodes. I also have a service to query block numbers and compare versus etherscan's current ...
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0answers
79 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: "...
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1answer
1k views

Where is storing events log? [duplicate]

I can't understand where are these events log data is stored? I can access to my logs by myContract.allEvents({ fromBlock: 2139049, toBlock: 'latest' }, function(error, event){ ...
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0answers
44 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 ...
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1answer
200 views

How to handle require/revert/assert errors properly

I'm trying to find an easy pattern to revert/rollback a write transaction. The first idea was to log a GenericErrorEvent but then I noticed that it will never be emited if any require/revert/assert ...
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1answer
390 views

How to connect with WebSocket with Web3?

Already referred web3 documentations and other Q-A for web socket connection. Currently using infura as provider.
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1answer
73 views

Not getting getPastEvents or once function using contract instance

I have followed Web3 documentation to subscribe an evnet, I have created Instance of web3 using infura url as argument. Created contract object using, const contract = web3.eth.contract(abi, ...
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5answers
21k views

How to access the event log by knowing the contract address (web3)?

How can I access a log stored in one of the tx of the contract via web3? Code example: event newtest(string indexed name, uint indexed idlevel,string indexed multib, string objmulti, uint objnm); ...
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1answer
121 views

Truffle: 'func.call()' retrieves the return-value of a non-constant function

I've just learned that one can easily obtain the return-value of a non-constant function, by using myContract.func.call() (instead of myContract.func(), which retrieves a response object). Up until ...

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