All Questions

0
votes
0answers
3 views

shouldComponentUpdate() firing only when browser canvas size is changed [on hold]

I'm facing a peculiar problem in which every time in my Ethereum React DApp, a token purchase request is given by pressing a submit button. The shouldComponentUpdate() function is fired only when I ...
5
votes
1answer
36 views

After deleting all elements from an array, how much gas refund will be made?

Following answer and solidity_link says that: Use delete on arrays to delete all its elements. delete dataArray; This is exactly the same as dataArray.length = 0 From this answer as I ...
0
votes
1answer
8 views

Deploy Contract Syntax Error

I am testing a contract, when I run the truffle migrate command, in my deplyment contract located in the migrations folder the following error appears: var HelloWorld=artifacts.require (“./HelloWorld....
1
vote
0answers
17 views

How can I recover the path to a specific transaction in the tx patricia merkle tree?

I'm working on a project where a non trusted entity is running an ethereum node (either geth or aleth), and has to pass information along to a non networked party. Namely, the non networked party ...
0
votes
0answers
13 views

how is GET https://solc-bin.ethereum.org/bin/list.json net::ERR_CERT_DATE_INVALID corrected?

I am trying to load Remix via the website in Chrome. Reported here - https://github.com/ethereum/remix/issues/1167 I get mock compiler: source not found and in the console - GET https://...
0
votes
0answers
7 views

Warning: myJS defines an invalid contextType. contextType should point to the Context object returned by React.createContext()

I'm using DrizzleContext of drizzle-react package. I'm deriving the context object using the following code: static contextType = DrizzleContext.Consumer; the derived context object is then ...
0
votes
0answers
18 views

How to make ECDSA signature of (value_1, value_2) with web3 on Python?

I want to call function with four parameters. I know how to create two of them, but the last two is the r and s components of ECDSA signature of (param_1, param_2). I tried this (and a lot of ...
1
vote
1answer
23 views

How to pass bytes32 to Web3.methods.function.call

I have a contract that is doing an ecrecover: function recover(bytes32 h, uint8 v, bytes32 r, bytes32 s) public returns (address) { return ecrecover(h, v, r, s); } It works ...
0
votes
1answer
24 views

Accessing one smart contract contained in another smart contract from javascript

I'm cross-posting this from Stack Overflow, since there seems to be more activity here. I am trying to develop a dApp with Truffle and want to test my smart contract. The contract contains a second ...
0
votes
2answers
25 views

Solc error invalid opcode, but works in truffle

I am trying to compile solidity code in solc(nodejs) but unsuccessful so far. I have created a sample app for demo. Here is sample's directory structure (node.js and truffle combined): │ app.js │ ...
0
votes
1answer
20 views

“web3.eth.accounts” doesn't output account address

I follow the instruction video "Code Your Own Cryptocurrency on Ethereum (Full)" from Dapp University on youtube. What is different when i use web3.eth.account. Here is from tutorial Here was i do ...
0
votes
1answer
20 views

How to show the time when the blockchain contract called? [duplicate]

I want to show the time when blockchain contract called. I am currently saving the time in the blockchain using a method like this function userCheckIn(uint placeid) public { userCount++; ...
0
votes
2answers
34 views

How can the smart contract auto execute the function in the private chain?

I know currently, we can use the Ethereum Alarm Clock and Aion scheduling system to execute the function automatically, but according to what I know, it only can work in Main Net and Test Net(Rposten)....
1
vote
1answer
11 views

Can ganache-cli connects to another ganache-cli?

Is it possible to create a private network using ganache-cli? Can a ganache-cli running on port 8545 connect to ganache-cli running on port 9545? Can we use ganache-cli as a node? Or it is a ...
0
votes
0answers
11 views

Is there any opensource Ethereum wallet which supports NFC?

Looking for Ethereum wallet with NFC(Near field communication) Support. Please let me know if there is any opensource app.
0
votes
2answers
18 views

How to restrict ICO investors to redeem their ERC20 tokens while not restricting them to trade tokens among themselves?

We want to create an ICO where investors can purchase ERC20 tokens anytime but have to wait for atleast 3 months from the date of purchase in order to redeem/encash them on our platform. But we do ...
0
votes
0answers
20 views

Why does return address(player) return a weird string?

I am trying to get the player's address through front end and when I run through the solidity function that should return the player's address, it would return ...
0
votes
1answer
22 views

Contract change registry

If i have a smart contract stored on block 10, when i change the status of this contract, the altered contract will be stored on the next block or the status of the contract will be stored in block 10 ...
0
votes
1answer
22 views

Is it possible to deploy a contract from python web3 if I have the ABI and bytecode from Remix?

Question says it all. I have a contract that I've written and compiled via Remix. I've dumped the ABI and Bytecode into local files, and I'm reading them into my python application. I'm following the ...
5
votes
0answers
653 views

Why should I vote and accept answers? [migrated]

As a new user, how should I decide to upvote and downvote questions, answers and comments?
0
votes
2answers
41 views

How do I monitor 50k addresses for incoming ERC20 transactions?

I have a list of 50.000 Ethereum addresses which at any time may receive ERC20 transfers. I know I can create filters but I don't think it scales to send 50.000 RPC calls to an Ethereum node every 20 ...
0
votes
0answers
5 views

Checking outgoing TX from duneanalytics.com query [on hold]

I am trying to run a script from explore.duneanalytics.com to check outgoing tx from an array of addresses but get the error: Error running query: syntax error at or near "output" LINE 9: WHERE "from"...
1
vote
1answer
18 views

How to encode function call in C

I understand web3 can be basically used for every existing task, however, is there anything we can use for C? My C program is communicating with the RPC server using the curl library, by posting JSON ...
0
votes
1answer
15 views

ganache-cli: how to persist new created accounts

I start my service by: ganache-cli -d --gasPrice 0 -q --db=./db This persists my 10 defaults created accounts, but when I create new accounts using Web3: web3.eth.personal.newAccount('password') ...
0
votes
0answers
16 views

Using traditional identities on a private Ethereum blockchain & wallet-less usage

I am trying to integrate a DApp (typical solidity, web3.js setup) running on a private Ethereum blockchain with a traditional enterprise user directory (let's say Azure AD). The idea would be : at ...
1
vote
1answer
39 views

Decrypt message on-chain

I want to store some data in smart contract and then decrypt it on chain. Pseudocode: contract EncryptedData { bytes data; string public decryptedData; constructor(bytes data_) public { ...
0
votes
0answers
10 views

Ethereum testrp connection

I'm using web3 in an android app and I'm to get the provider to be able to call the function within the web3 library to work but fails. This is the error i get Attempt to invoke virtual method'...
0
votes
2answers
14 views

connect users to the sidechain SKALE

SKALE is Ethereum Dapps to run high speed, Low cost smart contract layer. I wish to connect users to the sidechain SKALE,from their browser. automatically without the manual change as necessary for ...
1
vote
1answer
22 views

add fields to ERC721 tokens, still belongs to the standard?

if starting from the code of an erc721 token, I add fields beside the name, symbol and URI, is it still a token that respects the standard? Add in the contract, not in the JSON file. The most ...
0
votes
2answers
36 views

Metamask not returning current account address with web3js and ganache

How to return the address of my current account from Metamask? I have tried with web3.eth.getCoinbase() but this and metamask has two different address. web3.eth.getCoinbase() returns me the first ...
0
votes
1answer
25 views

Gas estimation failed: gas required exceeds allowance or always failing transaction

I have two contracts one for defining token and other for crowdsale. I am using remix ide. pragma solidity >=0.4.22 <0.6.0; contract owned { address public owner; constructor () public { ...
0
votes
1answer
8 views

Can Hyperledger Fabric Blockchain Supports Partial Transaction Encryption?

My use case is that we need to protect only sensitive data in the transaction in blockchain. But we want to open other data in the same transaction to the public, Can Hyperledger Fabric supports the ...
0
votes
0answers
21 views

How long does a smart contract typically take to complete?

I have been developing an application using a smart contract, the application is similar to this one: https://www.ethereum.org/crowdsale I went ahead and initiated a request, below is the codebase ...
0
votes
1answer
22 views

This contract object doesn't have address set yet, please set an address first

I am in the final stages of developing an application that is similar to https://www.ethereum.org/crowdsale, however, when I click on the create button, my Metamask modal is not popping up to ask me ...
0
votes
2answers
11 views

Problem making solidity contract compatible with version 0.5.0 or higher

pragma solidity >=0.5.0 <0.6.0; contract Courses { struct Instructor { string age; //add memory to struct varibles string fName; string lName; } ...
1
vote
0answers
8 views

During gas-free transaction get an error “No relay responded! 4 attempted, 4 pinged”

I did all modification related to this instruction https://github.com/tabookey/tabookey-gasless However, when I'm trying to write some tests it fails and provides me the following error Error:...
0
votes
0answers
7 views

Could someone explain to me the use of the FastRawTransactionManager class?

int pollingInterval = 3000; FastRawTransactionManager fastRawTxMgr = new FastRawTransactionManager(web3j, credentials, new PollingTransactionReceiptProcessor(web3j, pollingInterval, 40)); From what I ...
1
vote
2answers
27 views

How do I recover the address from message and signature generated with web3.personal.sign?

Is there any way to do that? To recover address in nodejs server-side from signature and message after it was signed with web3.personal.sign client-side? I tried this: https://ethereum.stackexchange....
0
votes
0answers
17 views

How to use 'geth attach' with Infura?

I have a project in Infura and the project ID is 6f...3a. I'm having problem to start geth attach process with Infura. I tried all protocols (http, https, ws and wss) but all failed. Did I miss ...
0
votes
2answers
20 views

Integer overflow checking

In the code of Coin contract at: https://solidity.readthedocs.io/en/latest/introduction-to-smart-contracts.html#subcurrency-example there is the following function which requires the amount to be ...
0
votes
0answers
22 views

Get RPC URL / IP of Metamask's current provider

Suppose I have multiple copies of the same dapp running on different servers which do not directly communicate with each other, for testing purposes, and can manually interact with different dapp ...
0
votes
2answers
16 views

Where do I find the literal error definitions thrown by the Ethereum Network?

I've been trying to create an Ethereum Transaction but keep getting the 320000 invalid sender error. From other questions I've seen, this may be caused by errors in signing, sender address or chainID, ...
0
votes
1answer
15 views

How does the MetaMask work with gas?

I have some web application based on Ethereum. This is how I call some function from a contract: contract.doSomething.sendTransaction(data, {gasPrice: web3.toWei(10, 'Gwei')}, callback...); This ...
1
vote
1answer
13 views

Can anyone with part of the chain (e.g. a light node) read unencrypted transaction data?

I need clarification on the fact that "the blockchain is public and anyone can read it". Given a node which is storing only, say, 1 block from the blockchain, can that node read the transaction data ...
0
votes
0answers
41 views

Currently you have no contract instances to interact with in Remix [closed]

I get this error "Currently you have no contract instances to interact with", when I change the environment from "Java Script VM". Then I found the solution for the above error where I changed the ...
1
vote
1answer
20 views

is there a list type in solidity?

I know there are dynamically sized arrays, but I need a data structure that can remove elements from the middle cheaply. Using pop() with a dynamically sized array should require a shift of every ...
0
votes
1answer
24 views

invalid number value (arg=“_goal”, coderType=“uint256”, value=2000000000000000000)

i am following a tutorial from here. And upon running truffle test. It produces following error. 2_HashnodeCrowdsale.js ====================== Deploying 'HashnodeCrowdsale' ------...
0
votes
0answers
9 views

DeclarationError: Identifier not found or not unique and Undeclared identifier

I am trying to create a crowdsale contract using zeppelin. But i am facing following errors. CrowdSale.sol:6:46: DeclarationError: Identifier not found or not unique. contract EdCoinCrowdSale is ...
0
votes
0answers
11 views

Function doesn't return any value but modify the data in the contract

I have a function that can retrive all data and one for retrive only not readed data. On Remix with JavaScrpit VM it's work, but on Remix with my private blockchain linked with web3 provider the ...
0
votes
1answer
16 views

Contract gives erc20 tokens based on an event, to an empty wallet

I have a new wallet address and no ETH. I want to be able to request an amount of 10 erc-20 tokens. Because I do not have any eth on this wallet, I want to be able to get the tokens onto my wallet ...

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