All Questions

Drizzle will automatically use the injected Web3 object. But if there is now Web3 object, Drizzle will try to connect to ws://127.0.0.1:8545'. How to configure Drizzle to connect to Infura.io for ...

I have a function call which only reads data from contract but it still costs gas to execute: function foo(int256 x) public returns (bool) { if(tuna[x].validOnce == true){ if(dog[x] == ...

I want to deploy a smart contract that receive funds from two parties. The contract is initialized with some ethers from person (call it revealer), and another Recipient (name it fineRecipient) who ...

I am deploying a private blockchain and currently I can set "gasLimit": "0xE00000000" in my genesis.json and when I run eth.getBlock("latest") I see the proper gas limit and other settings. However, ...

so my truffle based application is communicating fine with my smart contracts on my private network, ganache and ganache-cli. I then deployed it to ropsten where i used the endpoint i got from infura....

What is the best way to handled nested contract call with web3 1.0? I'm trying to collect all data needed and format it into something useable. It could require 2 or 3 calls though. Is there a easy ...

I am getting some error(picture below) while trying to connect DApp with a backend. One day ago, everything worked fine, now I got an error: "basic auth failure". Contracts are deployed on Ropsten ...

I am getting Error: Returned error: VM Exception while processing transaction: revert when testing MyContract.deposit() Here are simplified versions of my code to highlight where the issue is ...

Most suggest that cannot use ERC20 token as payment gateway integration .Why?

I have a token contract. I want to allow a site to give away my tokens to its users. I read i have to approve the owner of that site as allowance to use a set number of tokens for giving away to its ...

Suppose I have: function func(uint256 x) external { ... } I would like to test this function via web3.js, with the maximum possible value of x. In a Truffle test, I have noticed that I can ...

pragma solidity ^0.4.16; import './SafeMath.sol'; /** * @title Equality * @dev the interface of PoSTokenStandard */ contract Equality { uint256 public stakeStartTime; uint256 public ...

I have a function that, according to the Unique ID of the car, gives me all its characteristics: function getCarArray(uint _carId) public view returns (uint[12] memory) ...

I don't understand well how to implement an smart contract to create a capped Token. If I want to follow the example of a simple token is easy: https://github.com/OpenZeppelin/openzeppelin-solidity/...

I have a function which returns address but it gives me error if I try to read it. I'll explain by a quick example: Solidity: contract TestOneReturn { mapping(uint => uint) m_Data; ...

Unable to get User Error The returned value is not a convertible string.

Having a little issue. I have deployed a Mock ERC20 contract on development network like so: const ERC20Mock = artifacts.require("ERC20Mock"); module.exports = async function(deployer, network, ...

I have the following code: function getBytes5() public returns (bytes5) { uint256 x = now; bytes memory inBytes = new bytes(32); bytes5 outBytes5; assembly { mstore(...

Two of the functions of web3 - web3.eth.accounts.wallet.load - web3.eth.accounts.wallet.save Mentioned in the Doc of web3, these are browser only functions. Already tried to test these function ...

Should I upgrade to the latest go-etherum before the Constantinople upgrade activates at Block #7280000? If I do not upgrade, will it affect my node to do transactions?

const HDWalletProvider = require('truffle-hdwallet-provider'); const Web3 = require('web3'); const provider = new HDWalletProvider( 'passphrase', 'rinkeby.infura.io/v3/mytoken' ); const web3 = new ...

I used the web3.eth.accounts.recover method to retrieve the ethereum address but I am getting an error. Here is the code: let v = '0x' + signed_nonce.slice(130,134); let r = signed_nonce.slice(0,...

I am using truffle 5 and ganache-cli. I've imported increaseTime as import increaseTime from './helper/increaseTime'; and the increaseTime.js file is like this export default function increaseTime(...

http://disq.us/p/1zvfcta Please solve and fix the error occured on the system.

I have made a sample contract using Truffle's pet-shop. I have also added the 2_deploy_contracts.js file. I have changed the solidity version and also the constructor() public {} to comply with the ...

I have two wallets: Wallet1: 0x8882528C7104e146E0500203C353C09922575385 Wallet2: 0xddCf0FeC78b5a20B9138F5DDb1357E3B60026a67 Each of them has more than 1 Ropsten ETH. Using web3js and Infura ...

I want to create wallet Dapp. Then i will become the owner of the contract then for the other user who will use my Dapp they will become the users for my Dapp.For every transaction they have pay the ...

as Quorum and Ethereum are developed in Go, would like to understand why Tessera, the new Quorum transaction manager to replace Constellation, is written in Java instead of Go? Thank you. Nathan Aw

I am reading this article : https://medium.com/@jgm.orinoco/why-use-the-withdrawal-pattern-d5255921ca2a It seems interesting. Could anyone explain the idea of the Withdrawal pattern in a simple way ?

If I am not mistaken, the following two assertions hold true for Ethereum PoS: An entity becomes a validator in the upcoming PoS block validation scheme by first issuing a special transaction to ...

Would this be an acceptable way to produce a random number dependent on the reward? Say if the reward is high enough to entice a miner to manipulate the block then the contract will utilize oraclize. ...

I've been following a tutorial to set up a simple voting application just for experimentation purposes but after installing truffle, it seems it won't connect. Heres the error I'm getting when I try ...

im trying to install Truffle and have run into numerous problems - made some headway after getting an earlier version of python but camt seem to figure out this error - could someone point me in the ...

I have a dapp that allows you to upload pictures into blockchain using IPFS and I would like to implement a buy/sell smart contract that will allow users to buy the pictures or to setup terms to sell ...

So I have a factory contract "RestaurantFactory" which i migrate, this contract creates another contract "Restaurant", after deploying the RestaurantFactory and calling createRestaurant() I receive an ...

Here is the transaction details that has transaction fee for 2,100 Ether ($309,267.00) only for sending 0.1 Ether. There is no fairness for users, hence accidentally adding a zero might cause them ...

Following Drizzle documentation, Drizzle instance can only be created with: const drizzle = new Drizzle(options) Where the options is mandatory. And trying to not pass options will generate an error:...

I am much familiar with Rails but new in the Ethereum. But base on my understanding, if I am going to build a Dapp. The web stack should not include the back-end system like Rails. But why there's so ...

I hope this question isn't too vague, but it would really help me to get some advice on from the community on this subject. Which testnet is the most suitable for testing of a dapp? Do testnet ...

I am unable to figure out why the props.query.address is returning "undefined". I am using next.js for routing. Please have a look at below screenshot, Please note the highlighted route, When i ...

Working through a little project using the Truffle Pet Shop as the starting point and hit a wall. It looks like this is the piece in App.js that fires the handleAdopt function: bindEvents: function() ...

I'm trying to migrate a simple contract on the ganache blockchain.But when I type 'truffle migrate' command in the terminal.It freezes for some time and then command execution stops without showing ...

I want to run an Oracle query periodically and my idea was to call getUTCTimestamp(0) for the first query where getUTCTimestamp is: function getUTCTimestamp(uint256 delay) payable { oraclize_query(...

I have a multisignature wallet(it is a different contract). I have some tokens to transfer to another address(token is an ERC20 and can transfer via (yourContract.methods.transfer(toAddress, amount)) ...

assume that I have a private smart contract between peers A and B using quorum blockchain. Then, the variables of the smart contract will be placed in the private state. My question is: Can I make ...

I have implemented PoA on private blockchain with following genesis.json. { "config": { "chainId": 1515, "homesteadBlock": 1, "eip150Block": 2, "eip150Hash": "...

can i call ERC20 token's transfer function in other contract? like transfer AToken from using BContract's function can I?

have anyone used the --ethstats for private net? I am trying to use it but I see below in the geth logs Stats server unreachable err="websocket.Dial ws://host:port/api: unexpected EOF" Stats ...

can we pay the gas price in form of ERC20 token without using the ether? if ERC20 token has a value.then can we pay the gas price in form of ERC20 token.

I just tried to buy a test ether from https://faucet.metamask.io but the faucet address which is supposed to give 1 ether doesn't have enough balance. Snapshot of the faucet address And when i ...