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Questions tagged [logs]

Questions dealing with the contracts or clients logs. The tag "events" may be more appropriate, see https://ethereum.stackexchange.com/questions/tagged/events

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1answer
26 views

Infura getLogs returns an empty result

I'm writing a crypto based system with PHP on Infura, and now I am coding a script to retrieve logs for a specific address. This is my code: $ch = curl_init($my_server_url); $data = array( '...
2
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1answer
29 views

Unique identification of transfers

https://github.com/ethereum/go-ethereum/blob/master/core/types/log.go#L40 // Derived fields. These fields are filled in by the node // but not secured by consensus. ... // index of the log in the ...
2
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0answers
16 views

Web3 Ethereum log subscriptions - removed field?

I am trying to subscribe to Ethereum events (via Infura) but I'm a bit confused. I am following this documentation: https://web3js.readthedocs.io/en/v1.2.0/web3-eth-subscribe.html#subscribe-logs ...
1
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1answer
58 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 ...
0
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1answer
31 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
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2answers
37 views

what is the transferfrom event signature?

I am currently writing a code that list all types of transactions in a given contract . my plan is to just check for all logs whether the topics[0] == an event signature of a function. and now i am ...
1
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1answer
110 views

Solidity: Raise events via Assembly using log3

I want to raise events from inside a piece of assembly code. I've extended the answer here with the function AssemblyEvent() which currently causes a runtime error. Working example: pragma ...
0
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1answer
48 views

Is it possible to get duplicates of the log events on Ethereum when we have a fork of the chain?

Let's suppose we have 2 chains of ethereum blockchain. When I fetching contract's log events from x block to getBlockNumber(). Will i get two or one the same log events from each block? Or ...
1
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0answers
35 views

Handling EOF when subscribing to Event Logs

I'm trying to subscribe to events logs to handle Transfer(address,address,uint64) events. I've followed this example. https://github.com/miguelmota/ethereum-development-with-go-book/blob/master/en/...
0
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1answer
54 views

Converting Log Topics to int64 correctly in Go

I currently use the code below to extract the ERC721 Token ID from Transfer Event Logs: txHash := newLog.TxHash.Hex() hexString := common.BytesToAddress(newLog.Topics[3].Bytes()).Hex() flowerNum, _ :=...
1
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1answer
151 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 ...
1
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0answers
22 views

Error deploying the subgraph: Internal error: Could not pick index node

I'm playing with "The Graph" example counter project. If all I do is change the contract address in the mapping.ts to the same Counter contract on Rinkeby, then try to deploy, I get this error: ...
0
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1answer
40 views

Who is “from” in case of inheritance in solidity?

I have the following code: // Test.sol pragma solidity ^0.5.2; import "./TestBase.sol"; contract Test is TestBase{ string[] name ; constructor() public payable { name.push("sheep"); ...
0
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1answer
103 views

How to interact with events from a smart contract?

can we get access to watch the event and get logged data from them and use it for processing in a smart contract? Like matching an state variable with the data logged by an event .
0
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1answer
51 views

Logs and events: How are arguments of “watch” defined?

In order to watch an event we can use: var temp; eventx.watch (function(error, result){ temp = result.args.val.toNumber();}); Question 1: What is the role of: function(error, result){ temp = result....
1
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1answer
346 views

Emit event while require statement fails

I would like to be able to log a result of a condition: if(time > 5) { emit Result("time is larger than 5"); } else { emit Result("time is less than 5"); } This will work just fine, but ...
3
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2answers
1k views

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() ...
1
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0answers
46 views

Read args object from particular block transaction in truffle console.

Hi I have question on how to read args from specific block transaction that are passed when event was called. I have triggered an event, my block is created and i got transaction tx. In the ' Logs: ' ...
3
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3answers
162 views

How to setup 'topics' for function getPastLogs ()?

Sir, I want to read the past event log by using getPastLogs(),but I got the whole log.I hope I can filter some log. I find I can setup the 'topics' in getPastLogs(),but it always fails. How ...
0
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1answer
155 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" ...
3
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0answers
156 views

Bloom Filters - is the blockchain filtered block by block?

I understand that bloom filters are used to quickly scan for log topics and corresponding contract addresses. I also understand that an 2048-bit bloom filter is stored in the block header. Question: ...
0
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1answer
26 views

Should I route forwarding contracts through a second forwarding contract?

This is more of a question of filter events, I guess. If I have 500k deposit addresses and they are all forwarding to one account and emitting event logs with address(this) and msg.value, would it be ...
2
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2answers
151 views

How to maintain history of changes in mapping?

I have a mapping variable in my solidity code which maps address to name. I want to maintain the history/log of every change that happens in this mapping. What is the best possible solution to it?
1
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2answers
1k views

How do I decode the transaction's log with Web3.py?

I can filter my events (please see), but instead of that if I know only the transaction hash and if its already deployed, is it possible to obtain and parse the transaction's log data using Web3.py? ...
0
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2answers
779 views

How to decode data parameter under logs in transaction receipt?

I went through many questions but I couldn't get my answer. web3 version -- 0.20.6 According to documentation event's parameters which are not indexed store in data parameter under logs. I want to ...
0
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0answers
40 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 ...
2
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1answer
34 views

Can ethereum logs be present while transaction is being mined, then disappear later?

Question about the ethereum blockchain: If I walk the blockchain like so: for block in blockchain: for transaction in block: receipt = getTransactionReceipt(transaction) for log ...
1
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0answers
52 views

Why do are the 'type' & 'removed' fields in receipt logs different between Ganache and Geth?

When I run a particular transaction and log the receipt, I am getting different results depending on if my EVM is Geth or Ganache. Specifically, Ganache returns receipt.logs[0].type: 'mined' while in ...
1
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1answer
43 views

What does the logger's address mean in Ethereum yellow paper?

In the Ethereum yellow paper Page 5 says that the log entry O consists of (O_a,(O_{t0}, O_{t1},...),O_d). And O_a means the logger's address. What's the meaning of logger's address? Does it mean the ...
0
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1answer
285 views

Solidity: msg.data vs bytes

This is a simple contract that has a function input_data(bytes data) and a simple fallback function that passes msg.data to function input_data. contract test_input_data{ address owner; event ...
2
votes
1answer
411 views

How to unsubscribe logs / events?

There are two ways to subscribe/watch to logs/events: Subscribe: var subscription = web3.eth.subscribe('logs', { address: '0x123456..', topics: ['0x12345...'] }, function(error, result){ ...
1
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1answer
211 views

Decoding Contract Log's “Data” field With eth-abi Throws Error: “Padding bytes were not empty: b'0x0000000000'”

I used this guide to create the code below. I suspect the error is somewhat related to the encoding processes I do to the strings, as that is the only place where I deviate from the guide. Here is my ...
4
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1answer
77 views

Different outputs on event log subscription

These are the two ways I found to track events on the Ethereum blockchain. One of them doesn't contain the data I need. Why not? Way 1 does NOT contain the data I need Result: subscription = web3wss....
7
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1answer
132 views

What is the capacity of the logsBloom?

The logs bloom filter in the block header has a size of 2048 bits. How many messages will it accommodate before the false positive rate is too high for it to be useful anymore? If a formula could be ...
0
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1answer
573 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(); ...
1
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0answers
112 views

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. ...
0
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1answer
24 views

Incorrect values being passed

I am trying to copy stored values using the following internal value. pragma solidity ^0.4.21; contract test{ event LogTest( bytes32[5] a ); bytes32[5] attr; function ...
0
votes
1answer
149 views

copying bytes32 values from map to array

I am trying to copy stored values from a map to an array. I have the following code: pragma solidity ^0.4.21; contract test { event LogTest( bytes32[5] a ); bytes32[5] arr; mapping (uint=...
0
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0answers
49 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 (){ .... ...
5
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2answers
1k views

how to interpret event data ethereum

I was able to use the EtherScan api to get an array with event logs. Now I need to read from the data stored inside. The event data exists out of: uint256, uint256, uint256, address, address, string. ...
2
votes
1answer
819 views

What does “Topics” mean in “Event log”? [duplicate]

When we invoke an event as follows : event MyEvent(uint256 indexed _id, bytes32 _action, bytes32 _player, bytes32 _actionState, address _owner); emit MyEvent(uint256(_public_id), bytes32(_action), ...
1
vote
1answer
223 views

Web3.js getPastLogs() fromBlock error

I am trying to get some logs from ropsten and here is my code: web3.eth.getPastLogs( { address: '0x3b873a919aa0512d5a0f09e6dcceaa4a6727fafe', fromBlock: 3292448, toBlock: 3292448, }, )...
0
votes
1answer
136 views

Why Event log is NOT shown in HTML page?

I want to see Event logs in UI. And for this, I use following code in JavaScript : var EnergyEvent = Coursetro.setEnergyEvent({}, {fromBlock: 0, toBlock: 'latest'}); EnergyEvent.watch(...
0
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1answer
312 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
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1answer
51 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(...
1
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3answers
235 views

How to get “event logs” similar to “remix”?

I have an event as follows : event LogNewObject(address sender, bytes32 indexed id, bytes32 sub_states_types, bytes32 sub_states_values, address owner); And this event is used in following function :...
1
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1answer
63 views

Only one topics args for event logs visible in the transaction receipt, instead of three expected

I have a Smart Contrat where there is some events like bellow : MyContract { event CustomerDataSendingToSeller(address _seller, string _hasheCustomerData, uint256 _orderSeq); function ...
0
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2answers
3k views

How to listen to events generated by an existing contract in web3 1.x.x?

Currently I'm unable to find a working solution. Let's say I have the following smartcontract: contract Manufacturer { event LogNewOrder(string order); string[] public orders; function ...
0
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2answers
48 views

How to see Logs of exceptions?

I'm using solidity compiler ^0.4.23, I added logs to the function at exception points like this: function firstSaleDelivery(address _beneficiary, uint256 rate) public onlyOwner{ require(!...
0
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0answers
663 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) ...