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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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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58 views

Subscribe to events using local geth in light mode?

I've followed this guide to subscribe to events. I succesfully subscribed to the new block headers using Infura provider. But when I try to use local geth node syncing in light mode, it connects, but ...
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34 views

How I can get parity logs for non-mainchain blocks?

There's no much info on how parity event log works. What happens to event logs that correspond to block which is not mainchain anymore? Are they unrecoverably lost? For such an occasion, is there any ...
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How to filter MyEvent({ },{ }) to retrieve only the latest transaction in the array?

My code: instance.MyEvent({}, {fromBlock: 0, toBlock: 'latest'}).watch(function(error, event) { if (!error) { console.log(event); $('#events').html(event.transactionHash); } else { ...
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1answer
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Events in hub/factory contract

I have written a contract with the hub/factory pattern in which I need to capture the address of the contract that is being created, for this I am using events. Contract A Function A1 -- Call to ...
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Can't get event data selecting the event by name

This is my contract pragma solidity ^'0.5.2'; contract MyContract { event ContractCreated(address newAddress); constructor() public { } function createOtherContract() public { ...
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Web3 Daemon Event listner

const DManage = new web3.eth.Contract(myABI, '0x9420D0904B2F696f8612239e5a507A86B5dA1b6a'); DManage.events.allEvents() .on('data', (response) => { console.log(event); }) .on('changed', (...
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How do newHeads and event subscriptions behave on past reorgs?

Based on the geth documentation, I understand that a subscription on both newHeads and logs will emit all new heads and events that come from a reorg. However, I couldn't find what the behaviour is ...
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One rpc connection faster than another

I have four synced peer nodes running on two separate machines. Nodes 1-3 have been around since the beginning of the block chain and are all on one machine while Node 4 was just added around block ...
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1answer
438 views

Call `getPastEvents` with Drizzle raise error: “getPastEvents is not a function”

Calling getPastEvents with Drizzle will cause the exception: TypeError: this.drizzle.contracts.Contract.getPastEvents is not a function How to get all the past events in an array (in-one-shot) ...
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drizzle not updating events properly - duplicate events

I'm facing a peculiar problem while rendering event values in a component using drizzle. When a new event is created and is updated in the events array of drizzle (drizzleState.contracts.MyContract....
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224 views

How to handle events using drizzle?

strange that after much searching, i havent found even one piece of info out there which clearly elaborates on how the events are manipulated in drizzle. From what i understand, the event names (and ...
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61 views

Accessing the Ethereum State Variables using web3js (Java Script)

I'm trying to run the below code to get the state variables using the getIdBytes method of the Smart Contract, and assign it to a java script array variable, but it doesn't seem to work. All I can ...
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390 views

About getPastLogs usage

"getPastLogs" can get past event log. I check the web3 documentation: fromBlock - Number|String: The number of the earliest block ("latest" may be given to mean the most recent and "pending" ...
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What is the most preferred way to listen to events

After studying about solidity events, my understanding is that receiving an event doesn’t guarantees that the transaction is final. Transaction may yet to be included into the block. And even if it ...
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3answers
234 views

Reading the result of a function that change state by using events in Solidity

I would like to get the result of a function by listening its emitted event. These are two pieces of code of my contrats CONTRACT 1: function createTradeableContract() public stopInEmergency ...
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1answer
57 views

Filter topic across multiple contracts

Is there something I could add to my contract which allows my application to filter for all the deployed contracts which also included this topic/identifier? The only other option to manage this I ...
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87 views

Watch Events with same Name but different params

using web3@0.0.xx is there a way to get Events overloaded (with the same name, but different params) ? I found contract.Transfer[‘address,address,uint256,address,bytes’]({ fromBlock: 0, ...
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1answer
544 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" });
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Filtering blocks on basis of transaction logs in web3j

I want to filter blocks on the basis of a log present inside transactions. How can I do that? I don't have any contract address and want to filter all the blocks generated by all the contracts. ...
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Why would an Infura/MetaMask watch of a contract's allEvents() that works on Rinkeby fail sporadically on Mainnet

I have some code that immediately sets up an allEvents watch for the contract, then leaves that running and uses it to handle various events generated by the contract. I've been running it on Rinkeby ...
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Is there any specification for Decentralized Token Exchange?

Is the way of doing decentralized token exchange (DEX) on Ethereum blockchain specified in some ERC ? Exploring event data in Etherscan I found that there are many types of events: event Order(...
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3answers
566 views

Not able to export to csv all transfer events of a specific contract on Ethplorer.io

I'm able to use the Export to csv function, but it's only giving me the most recent 1000 events. Any suggestions on how to get ALL (2100+) of the events in a csv file? https://ethplorer.io/address/...
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Solidity triggered event that shows a message to everyone who is currently in the site

Just a small question regarding how solidity event works. Let's say I have a function buyCandy(). At the end of the function I attached event: emit LogBuyCandy(msg.sender); event LogBuyCandy(address ...
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196 views

Listen for Solidity Event With X Number of Confirmations

I presume Solidity events are fired the moment the block that includes its transaction is mined -- please correct me if I'm wrong. I need to sync the transaction status locally but wish to only save ...
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134 views

web3 got duplicate events and make data in server different from blockchain

I use web3j to listen ethereum smart contract events to synchronize data for the server, but sometimes I got duplicate events in one function. Let's consider Birth evens in CryptoKitties smart ...
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706 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?
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1answer
306 views

Event unique identifier

The web3.js (1.0) docs helpfully list the return values from a contract event subscription. I've noticed that there is an additional return value id that isn't listed there but is returned with the ...
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1answer
797 views

Geth settings for watching Events?

what are the optimal geth settings if you just want to listen to some events that are fired by smart contracts? I'm having a bit trouble to setup geth properly. Thanks a lot. PS: That is my ...
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777 views

Recommended way to watch events with MetaMask?

I always get in trouble with things like var filter = web3.eth.filter({fromBlock: '5139365', toBlock: 'latest'}); filter.watch(function(_err, _resp){ ... when using MetaMask as provider. What is the ...
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820 views

Web3 Solidity events do not work any more in Chrome?

Ok, it seems like this issue is only present in chrome browser I am working with Version 64.0.3282.140 (Official Build) Built on Ubuntu , running on Ubuntu 16.04 (64-bit) Actually I had some ...
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2answers
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How to include the named of the called contract in Event Log

in my code I am using events in order to log some date. I would like to include the name of the contracts I am calling out of my main contract into this event log. Does anyone have an idea how to do ...
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Get root data of smart contract

I am deploying a Smart contract with set of fields. Updating some fields using events.Till here is fine. Now here i need to fetch the root data(data while deploying the contract) Please suggest. ...
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Tracking transaction attempts/failed attempts sent to a contract from unknown parties

In light of the recently killed parity library and how the person responsible went around randomly trying to kill contracts, is there a way of monitoring smart contracts for attempted and potentially ...
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109 views

How to best react to geth events from a server app?

I have a geth node running on a server. I want my Ruby app to take action every time a contract emits an event. The app cannot miss any events. One way would be to poll for transactions to that ...
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1answer
206 views

Remote geth node failing to retrieve past events

I have set up a remote geth node on AWS as a web3 provider for my DApp. The geth node is initialized with the following command (for testnet) as a daemon service: [Unit] Description=Ethereum go ...
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I am trying to query historical blocks for specific events from my contract. Is a full node required for this? Or is a light node or fast node fine?

I am having difficulty seeing any events for my contract. They show up in etherscan but not when trying to view them using web3. I am running a light node. Do I need a full or fast node to have access ...
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Date-Span in Event Filter

Want to provide an interface on my page to show filter based event data. Haven't come across a proper working example to fetch event data by providing a date span. So it will be helpful if one could ...
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763 views

How to continue to watch the `Events` from the point `geth` was closed?

I have a private Ethereum network. The bootnode(main node)'s goal is to watch Events and if a new Event is generated than trigger a contract's function that I want to run. The key point is triggered ...
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Need help understanding Events

Here's an example from solidity docs: [SOLIDITY] contract ClientReceipt { event Deposit( address indexed _from, bytes32 indexed _id, uint _value ); function ...
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Listening for events on real time with Web3

I want to update UI elements of an app based on contract events. My problem is, that I do not receive any events that happen after the site has been loaded (seems like the subscription does not work). ...
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How to test if a transaction create a specific event using the trace api?

I need to frontrun a transaction on a specific contract only if does a specific thing which is fired as an event once included in a block. So how to get the event based on current contract state of an ...
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Python Web3 get all events

I am using web3 5.14.0 and Infura I am trying to get all transfer event for link chain token like the following: from web3 import Web3 ABI_REQUEST_ENDPOINT = 'https://api.etherscan.io/api?module=...
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Events and callback

I can't quite understand how events work with web3.js. Events work asynchronously and callbacks are executed when the result returns. These callbacks are already defined or I have to write them myself....
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1answer
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How does myContract.events.MyEvent ([options] [, callback]) work?

I'm trying to understand how events work. My contract emits an event which is captured by the node (I'm using web3js). I need to extract the submitted parameters (msg.sender, id_, location_). I need ...
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How to catch a solidity event from Java

I am trying to make a decentralized android application. It is an online two player Tic-Tac-Toe game. I have implemented the back-end with solidity and a part of the front-end in android studio. ...
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1answer
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Ethers.js filters events (Only new events)

I have an event set up in the Contract. Contact Packages emit Spend(msg.sender, msg); function sendPackage(msg) external payable returns(bool) { require( msg.value == price, '...
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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, ...