Questions tagged [ethereumjs]

For questions regarding the installation or use of EthereumJS, a Javascript library that implements a number of Ethereum utility functions.

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Why do we use `serialize` function of `ethereumjs-tx` package before broadcasting a transaction

I just want to know the purpose/functionality of serialize function which we use before broadcasting a transaction: const serializedTransaction = tx.serialize() const raw = '0x' + ...
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20 views

How to resolve this error in solidity “The constructor should be payable if you send value.”?

In this solidity code the finalizeRequest() is giving a run-time error. Here is the error : Campaign.finalizeRequest(uint256) 0x692...77b3a transact to Campaign.finalizeRequest errored: VM error: ...
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1answer
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How can i use Token from an ERC20 Contract in my own contract?

I have following contract here on ropsten https://ropsten.etherscan.io/address/0x813870feba76f27ec1afcf79432e065a4839f7ab#code I want to use tokens from a different erc20 contract(...
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How can I approve and buy for another contract? [closed]

Im having this contract here https://ropsten.etherscan.io/address/0x813870feba76f27ec1afcf79432e065a4839f7ab#code This contract "TOKEN"(agi.sol) first needs to approve an transaction amount from a ...
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2answers
75 views

why did this transaction fail?

I have a smart contract on Ropsten that I'm testing: 0x813870feba76f27ec1AfcF79432e065A4839F7AB Transaction has failed(reverted). What is the problem, because I don't see an error message ...
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24 views

Metamask and Ether.js API

I am trying to use the ether.js API with Metamask (with Ganache GUI i.e. localhost 7545) via the Chrome console. I am getting an error saying that ethers is not defined. > let currentProvider = ...
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1answer
19 views

DApp Design Consideration

Does a site like Cryptokitties query the blockchain in order to verify which ERC-721 tokens a specific user owns upon logging into his wallet, or does it store the list of owned tokens locally in a ...
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How do you recover in web3.js 1.2 a message signed with web3 0.2? [duplicate]

MetaMask injects 0.20 and you can't switch it off or mix web3 versions (not easily anyway). I am forced to use this method for signing: web3.personal.sign(web3.fromUtf8(nonce), web3.eth.coinbase) It ...
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1answer
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Return a value from send function [duplicate]

Hi guys i have one really big problem. I have this pice of code function showInfo(uint _pesel) public onlyMainPerson(msg.sender) returns (string memory, string memory) { string memory x = ...
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How to open multiple terminals using docker?

Here I am trying to create private ethereum instance using dockerfile. I want to open two terminals and run command1 in terminal1 and execute command2 in terminal2 only when command1 returns true. ...
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input field is not getting displayed by using ContractForm

<DrizzleProvider options={drizzleOptions}> <LoadingContainer> <div> <h1>Welcome Doctor</h1> ...
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Recovering of typed signature fails because it's too long

I have a typed signature generated by EIP712 V3. It is 132 characters long. I'm trying to recover it using recoverTypedSignature from eth-sig-util. This fails saying: index.js:1 Error: Invalid ...
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1answer
33 views

Could not find declaration module for file 'solc'

I was trying with a simple contract,when I do "node compile.js" in my windows cmd it throws an error.I was using vscode it showing error in const solc = require('solc'),I installed everything ...
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25 views

Why does Infura Ropsten websocket filtering event timeout?

When listening events via Infura Ropsten websocket, web3.py implementation timeout while web3.js succeeds. The demo can be cloned from -- https://github.com/jerryji/ropsten_wss_timeout_demo After ...
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1answer
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What does it mean to serialize a transaction?

In tx library there is a function: serialize() that "serializes" your transaction object. You can then convert that serialization into hexa decimal string, and use it to send the transaction with the ...
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Extract function names alongwith their parameter name and types from abi JSON file

My task is to get function names, its parameters and type of parameters from provided .json file. Then call each extracted function with extracted parameters. The code from this Get all function names ...
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1answer
22 views

Could not call contract function

I want to access the balance of contract(i.e. 0x552F3AfaA0394632f4aEfa9E923fA3e2bbDAF5FE) and its totalSupply(state variable). I could access the balancec of this contract , but why I could not call ...
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pass struct from web3 python interface to solidity

I have created a smart contract with some solidity functions which take structs, enums and mappings(all defined in my contract) as arguments. I intend to call these functions from my web3 python ...
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2answers
31 views

Calling smart contract functions and submitting transacions in BACK-END in high level

I have read some references to create ethereum transactions by a BACK-END server, all in low level, for example, requiring that I control the nonce by myself. Are there safe ways to avoid this control ...
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3answers
34 views

Could not assign contract state variable value to javascript variable

I want to retrieve and assign the value of my contract state variable to my javascript variable.I am doing as per guidlines provided on this community, but failed to assigned. my javascript code is ...
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SendSignedTransaction is not sending tokens

I tried to use sendSignedTransaction function, it signed and sent the transaction successfully(i think), but it's not transferring tokens as it ought to. It's basically not doing the intended task 😔 ...
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2answers
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How to edit transaction data of an ethereum transaction? Or in other words, create a manual transaction, for contracts with no front end?

This strikes me as a very stupid question, but I have googled and cannot find an easy answer. I have identified a contract that I want to interact with- I know the function selector and the variables ...
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1answer
40 views

Contract deploy error with Cannot create property 'from' on string

I am getting this error, when I deploy contract by using web3. TypeError: Cannot create property 'from' on string '...
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1answer
32 views

How can a smart contract payable based function returns value against any purchase

I am trying to get a return value from the payable function, the idea is a user must pay the fees and in return, he will get his special code. My JS test code is as follow it('get special code ...
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What is the networkid and chain id of truffle cli?

I am using truffle console to deploy contracts and using Nodejs/web3js to interract with it. I wanted to use ethereumjs-tx for signing transaction, here is the reference link. I am not sure ,how can ...
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1answer
39 views

rpc error with payload and exception thrown in contract code

This is the problem I get when trying to run my contract! And then when I go ahead and run it, this pops up This is my js code: import React, { Component } from 'react'; import Web3 from 'web3'; ...
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2answers
72 views

Exchange ERC20 token with other ERC20 token

I have 2 ERC20 tokens. The contract are designed as standard ERC20. Here are the 2 tokens to take as an example - AUDC --> Contract Address: (0xContractAUDC) Wallet Address: (...
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1answer
15 views

Geth and JavaScript

I want to deploy a private blockchain using Geth. I am considering using JavaScript to build the backend as I did before (NodeJS) but what about the smart contract? Since it is private is there a way ...
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1answer
31 views

How to parse ecrecover parameters?

I am looking into getting the public key from ANY ethereum address (not owned by me) that has sent a transaction at least once. It seems that the most viable solution here would be to use ethereumjs-...
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2answers
37 views

I Call SmartContract Token ERC20, Why Show Hashing Output ? (Web3 + Metamask + Javascript)

I do not know why with this, even though in the previous version (web3 + Metamask) can issue real data. But now used as hashing (output). I took the example in the code and output below (to get the ...
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3answers
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How to build a decentralised Voting Website without using any 3rd party extensions like Metamask, or IDEs like Remix? [closed]

I've gone through various Blockchain Tutorials but everywhere it's one or the other same thing. Download truffle/ganache, from 10 free testrpc account, use one, use metamask, Remix IDE etc, and Voila!...
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Transactions go to an older contract address rather than the present deployed one

Though I have deployed a new contract but the transactions go to a previously deployed contract in my application. I'm attaching the screenshot of my Remix-ide code and the code for the front end ...
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1answer
309 views

problem connecting web3 v 1.2.1 with metamask : 'currentProvider' of undefined

I am using Web3 v1.2.1 with nodejs v10 and following this link. I am having issue connecting with metamask,below is my code snippet: const Web3 = require('web3') const window = require('window'); ...
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1answer
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Code:const web3 = new Web3(window.web3.currentProvider) Error: window.web3 is undefined

I am going to connect my contract with the website.However,there was something wrong with the web3? I'm not sure. import Web3 from "web3"; const web3 = new Web3(window.web3.currentProvider); const ...
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1answer
130 views

Which version of web3 shall i be using now?

I found the documentation of version 1.0.0 which was released on the 6th of August here. I was told that v1 is not stable and very different than earlier versions. But when i check the available ...
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3answers
79 views

transferFrom function not working in ICO Smart contract

I am facing issues with the transferFrom function of smart contract address 0x6560a9b6436e129cf835ab9da96201207facd4f8: I copied the smart contract code from etherscan.io and deployed on ropsten ...
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1answer
133 views

How do I use web3js 1.0.0 in geth 1.9.0? I want to import an account whose address, private key and passphrase I have in my geth node [duplicate]

I am at Geth/v1.9.0-stable-52f24617/linux-amd64/go1.11.5 web3JS version is giving : > web3.version { api: "0.20.1", ethereum: "0x2712", network: "4", node: "Geth/v1.9.0-stable-52f24617/...
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Error: Keystore: Must include seedPhrase in createVault inputs. How to fix?

i'm studying blockchain development, and i'm trying to create wallet with seed words using eth-lightwallet and vuejs. But i receive this error: Keystore: Must include seedPhrase in createVault inputs, ...
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0answers
23 views

What is the difference between signing a document, signing a transaction and signing a message? (very basic)

As per my limited knowledge in Ethereum, user can sign the object(doc, Tx, msg) for the security purpose and with the public key other user can get that object. But not understand the difference ...
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50 views

How do I perform a fully anonymous transaction using Stealth addresses in Aztec protocol?

I want to know how to make use of Aztec's stealth address protocol.
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Can I Create Node.js API for each function in Smart Contract but sign a Transaction from frontend via Metamask.?

I am trying to develop a Dapp with nodejs backend but I cannot get accounts from Metamask which resides on my frontend. I tried to create an endpoint for each function in Smart Contract. And it seems ...
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1answer
33 views

How to know in advance the gas used by a transaction?

I want to send an ERC20 token (Ropsten network). So I execute a function 'transfer' on a contract. When The transaction is sent, I can get the gas used in the receipt. Few months ago this amount was ...
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Is there a way to broadcast/send transaction using web3js using token that is not ethereum?

My question is: I am trying to send a transaction using a cryptocurrency very similar to ethereum, in fact their code is almost copy pasted from ethereumjs: https://github.com/CSEPlatform/cse-tx/blob/...
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1answer
218 views

'ALERT: Trying to call a function on a non-contract address' Why Do I Keeping This Error?

This is the error from metamask directly: This is the error I get once after I submit the information to IPFS: My Smart Contract: pragma solidity 0.5.3; //Imports for safe math operations import "...
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1answer
61 views

Why txHash in sendSignedTransaction giving Undefined value on sending on rinkeby testnet

let Tx= require('ethereumjs-tx').Transaction; const Web3= require('web3'); const url='https://rinkeby.infura.io/v3/d4dbc79ea192404fb42689cc55ce2fc0'; const web3 =new Web3(url); const account1= '...
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0answers
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Error using drizzle and react

My contract Storage.sol - pragma solidity ^0.5.0; contract Storage { string public data; function getData() view external returns(string memory) { return data; } function setData(...
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15 views

Error send token

let minABI = [ // transfer { "constant": false, "inputs": [ { "name": "_to", "type": "address" ...
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How to save contract address to database with web3js and mongoose when I deploying a contract?

I wanted to get my contract address after it deployed, and then save it into my mongoDB. But instead of that, my contract address is deployed after it. So my mongoDB won't save my contract address. ...
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0answers
54 views

which is a better method to use for signing messages between two parties in web3?

I have been searching for a while for the most secure and supported way for off-chain channel messaging.....so i was using web3.eth.sign(address, keccak256(msg)) for singing messages ....but then used ...
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1answer
115 views

How to use window function in controller (node.js)?

So this is my users controller to upload a file : exports.postUploadFile = (req, res, next) => { var ethereumURI = req.body.ethereumURI; var abi = JSON.parse(req.body.abi); var ...