I am running ganache-cli through a node application: const ganache = require('ganache-core'); const ethers = require('ethers'); const provider = new ethers.providers.Web3Provider( ganache.provide...

I am trying to connect Ethers.js to a local Ehereum node (Geth) running in a Docker container. On the client side, I'm creating the provider this way: new ethers.providers.JsonRpcProvider('http://g...

Using OpenEthereum, which is the json rpc call allowing to do it? I found the parity_pubsub module but I ve no idea of the parameter for getting not yet confirmed transactions. I also found https:/...

I want my smart contract to return 7 or 8 UNIQUE random numbers ranging from 1 to 100 upon calling the contract. What can be the best approach to obtain such result?

How to detect empty address that has initial value of 0x0000000000000000000000000000000000000000 in web3.js? What I'm doing now is: if (address !== '0x0000000000000000000000000000000000000000') {...

I am new to web3 and ethereum blockchain. I tried broadcasting a transaction using the following code but it always gives me an invalid sender error.The sample code is shown below. const Tx = requi...

Pretty new to Solidity and just tried the first HelloWorld smart contract in Remix IDE and stumbled upon this error, while trying to deploy the smart contract. creation of HelloWorld pending... cre...

So, I have been following tutorials of Eat The Blocks on ToDo List Ethereum DApp. Done till step 6, but while running the command npm run dev-front I am getting this error. > [email protec...

I was trying to create a python program to convert ETH to BTC. I was using the command : client.transfer_money("ETH Account ID ", to="BTC Account ID", amount="0.1", cu...

I have a query, where do blockchain data saved in every node. After a long search in google, StackOverflow, and some blogs, like got many answers: like: it saved in a database like level-DB or rock...

I am making a project using Ethereum. In this project , I am making a contract called "A". When I send a message to "A", I want "A" to make a web request. Is it possib...

I'm having trouble getting the python function web3.geth.txpool.inspect() to work. I've tried using a geth server from the command line, from the ethereum/client-go container, and from the truffle...

I am getting an error when passing (javascript array of objects) from web3js, To solidity function that takes (array of structs) as a parameter. could you help me? below is the code and the erro...

I have a smart contract that I’m trying to make, it pays out the winners of my League of Legends tournament. However I’m running into an issue. I need to make an API call to get the winner of the m...

Show Image as you can see the image above, the function 'custLogIn' is view type (free on ether) but after deploy the contract trhough Remix, it changed into non-free function. I want to know abo...

I would like to see the real-time pending transactions in the Ethereum txpool via Web3.py. I do not run a local node but use Infura instead. According to the documentation of Web3.py, apparently on...

When I try to do this in Solidity, it gives me UnimplementedFeatureError: Nested dynamic arrays not implemented here. I see this in code examples. Does Solidity not support this? Edit - posted comp...

For smart contract development, what is the difference between Openzeppelin SDK and Truffle? When should I use one or another, or both together?

How can i run abi.encodePacked in golang? in solidity i use keccak256(abi.encodePacked(a, b)) to calc the signature of the params. here is my contract. pragma solidity ^0.4.24; import "openzepp...

When one contract's function read data from second contract's function (that is, there is no state change on the second contract). Does it consumes gas?

The doc on github says: --allow-insecure-unlock Allow insecure account unlocking when account-related RPCs are exposed by http And, I have to add the option when start geth, otherwise can't un...

One of the much appraised features of blockchain among other things is traceability of data stored on the blockchain priced on records being immutable i think. I am trying to find out how state ch...

I am trying to setup a private ethereum network. I started two nodes in the same machine (Windows 7) in two different ports. I am unable to add one node as the peer of the other node. What I have ...

I wanted to config my truffle-config.js with provider. When I run command "truffle migrate --network ropsten", it throws this error: Error: Web3ProviderEngine does not support synchronou...

I am designing a solution for an ethereum smart contract that does bidding. The use-case includes reserving a name eg. "myName" and assigning to an address. And then, people can bid for that name (...