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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Approval notification

Is there a simple way that I can be notified (or check easily) when my address (an EOA) is approved by some other address (EOA, not contract) for an allowance of x amount of any ERC-20 token? It seems ...
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Web3 - OR condition between multiple filters in getPastEvents

Take as an example the event PairCreated(address indexed token0, address indexed token1, address pair, uint); defined in UniswapV2Factory's contract. Let's say that I want to fetch all the past events ...
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How can I access data of transaction topic?

I need to access the data from topic 2 below (see image): With this code I can render the topic hash, but not the topic data: contract .getPastEvents('allEvents', { fromBlock: START_BLOCK, ...
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Infura-Like caching layer to store all Events in local nodes for fast retrieve

Anyone who has tried to use a local Ethereum node to run any complex DApp will have realized that it is impossible to do so because there is a huge problem of slowness in the retrievement of large ...
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Referencing events of interfaces in libraries

When writing a contract and using an interface, events that are part of the interface do not need to be declared in the contract. Can this be avoided when not writing a library and emitting events ...
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myContract.getPastEvents returns undefined event

I am using Web3 1.3.0. Connecting using Node. Also if I try to enter the name of my Event I get an error saying that event does not exist. This is what I get, shouldn't event have a value ? I am using ...
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37 views

High level tool (autogenerated UI) to obtain all the events emitted by the contract?

I'm pretty sure something like this exists, saw it somewhere in the wild, my Google skills need some StackOverflow boost... I would like to provide two data points: contract address name of the event ...
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How can I view pending events, without much delay?

I can view pending events like so: pending_events_filter = my_contract.events.TestEvent.createFilter(fromBlock='pending', toBlock='pending') pending_events_filter.get_new_entries() But the events are ...
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Read transaction logs of another Smart Contract

I have to track user activity in DEX smart contract and do some validation/operation based on that information. DEX itself does not API to retrieve that info, but emit events, so is there any way to ...
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Does Infura support Event Filters?

Does Infura support creating filters to Listen to events ? I have a dapp with many events, and would like to test it in Ropsten testnet and python web3.py, but it seems infura does not support filters....
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Duplicate events from get_new_entries using web3.py

I'm struggling to understand how to properly poll events emitted from contracts. The provider I'm using is Infura. My code boils down to the following: filter = target_event.createFilter(fromBlock='...
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Recording Event Logs in a DB from a Smart-Contract

I have created a smart-contract and deployed to the Rinkeby Network, it has a client-side application which has been established with React. Now, I would like to observe and audit every transaction or ...
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How to display formatted transaction information in Remix IDE from web3.eth.getTransactionReceipt()?

tl,dr: Remix shows a formatted transaction summary for transactions that are initiated within the Remix IDE. Is it possible to display the same output for an arbitrary transaction hash? Sorry if this ...
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Subscribing to new blocks doesn´t work [ROPSTEN]

I'm trying to subscribe to newBlockHeaders on the ropsten network, but it does not seem to work. The following code works for mainnet but not ropsten. Any ideas? const Web3 = require('web3') const ...
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Event listener works correctly from outside of the machine but not from inside the machine

I have created an event listener for my application. When I run the event listener from outside of the machine it listens correctly to all the events but when I run the same event listener (with ...
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How to find a specific event if it has no indexed params

I understand that I can filter for logs with indexed events like so: event Transfer(address indexed src, address indexed dst, uint wad); whereby, I can search for all Transfer events with src=...
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Which Ethereum library is the one to use nowadays? Contract events on mobile must work

I used drizzle in our dApp and contract events work fine on Desktop browsers with MetaMask. However, on mobile (tested with Rinkeby deployment on MetaMask and Status on Android) the contract events ...
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How to use truffle-assertions to verify parameters of an emit?

I have not been able to find any resources with usage instruction besides github and blog post by the author On github an example is show as such: truffleAssert.eventEmitted(result, 'TestEvent', (...
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Why eth_getLogs returns empty result for Ethereum account address?

I'm developing an Ethereum platform and need to fetch the events log of a desired address. I found a code like this: curl -X POST --data '{"jsonrpc":"2.0","method":"eth_getLogs","params":[{"topics":...
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How to listen for contract creation, or all block events?

I'm building a web app with web3 where users can deploy a certain contract and assign some people to it. Inside the constructor of that contract I also output a certain event. I want these assigned ...
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How to filter an indexed event parameter using web3j?

I am planning to use ethereum logs as a data storage on my private blockchain. I have defined event in my contract like this: event logDomainFilter(uint128 indexed _campaignId, uint128 indexed ...
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In EtherJs how to find account number of balance change event?

I am creating Ethereum Wallet application & I am using EtherJs for Web wallet development. When I try to listen for Balance Change event for multiple accounts then How do I find account number ...
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How can I listen for Truffle Actions such as TX_BROADCASTED, TX_ERROR via the Drizzle Vue Plugin?

In my Vue JS Dapp, which uses Drizzle Vue Plugin, I listen for contract events using $drizzleEvents like so: this.$drizzleEvents.$on('drizzle/contractEvent', (payload) => { this....
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Ethereum Logs since Beginning of Time

I can subscribe to all events in ethereum network (logs, pendingTransaction etc) so I can get only newly generated events (while I am subscribed). For my analysis I need to retrieve all logs from ...
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How to log an event which emits state of the contract in nethereum?

I am logging a specific event from a specific contract using nethereum. However, my event emits contract state (enum in solidity). My log processor shows 0 events instead of 2. Solidity code snippet:...
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Failed to get events from kovan testnet. Same code working in ganache testnet

I'm unable to get events from kovan testnet. The same code is working with ganache blockchain, but when using kovan testnet. I'm not getting any response. Can anyone tell me what I have done wrong?. I'...
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483 views

Listening to events in Ethers.js with websockets

I'm trying to listen to all emitted events from a contract with Ethers.js and Websockets. Any idea why this is not working? var wsProvider = new ethers.providers.WebSocketProvider("wss://rinkeby....
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web3 filter function not working

I am trying to filter Transfer events from my local Ethereum node using web3 py. I am accessing my local ethereum node remotely using teamviewer and it was running and fully synced as well. My code is ...
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web3.js function contract.once() not working on Kovan, but working on ganache

I am subscribing to an event (just once, queued after an update) of a contract to reload the data like this on my react frontend: const instance = new web3.eth.Contract(abi, address) instance.once( ...
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What is the websocket URL in Ethereum on Geth?

I've lunched an Ethereum server based on Geth. Now, I need to be notified about all incoming transactions on my generated accounts. In my previous Bitcoin Core server, I had an option in its config ...
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Unable to hear emitted events

I'm using Infura as my provider. From what I've read online, it seems that using a websocket with infura instead of http is the first step to being able to hear events however I only get an empty list ...
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1answer
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Web3.JS 1.2.6 reporting PastEvents but not new events

relevant code: token.getPastEvents('Approval', { fromBlock: 0, toBlock: 'latest' }, function (error, events) { console.log("ETHEREUM past events " + JSON.stringify(events)); }); token.events....
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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 ...
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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 ...
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1answer
79 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 ...
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241 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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1answer
22 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 ...
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1answer
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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 ...
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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....
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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 ...
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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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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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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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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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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
655 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( "...
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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 ...
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1answer
79 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 ...
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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((...
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1answer
54 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 ...