Description

This voting dapp project were built for learning about blockchain, dapp and smart contract with NodeJS + Web3JS.

Run simulation blockchain

Run command

$ node_module/.bin/ganache-cli

for simulation full client behavior. it will show wallet address for being use to test

Deploy contract

Run

$ node

then you will be in node console, run command as following

> Web3 = require('web3')
> web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

above command were used to specific where does the blockchain run

> code = fs.readFileSync('Voting.sol').toString()
> solc = require('solc')
> compiledCode = solc.compile(code)

above command were used to compile file smart contract Voting.sol. it will generate object with bytecode and interface.

• bytecode is what we will put it in the blockchain. It works similar to backend
• interface is something like structure of contract that we will use to interact with the contract (abi)

> abiDefinition = JSON.parse(compiledCode.contracts[':Voting'].interface)
> VotingContract = web3.eth.contract(abiDefinition)
> byteCode = compiledCode.contracts[':Voting'].bytecode
> deployedContract = VotingContract.new(['Rama','Nick','Jose'],
{data: byteCode, from: web3.eth.accounts[0], gas: 4700000})

above is assigning an abi and deploying contract

> contractInstance = VotingContract.at(deployedContract.address)

finally, pair abi to address where we put the contract

Edit & run Dapp

1. Edit file index.js by change contract address to where your contract were put deployedContract.address

2. Open file index.html ผ่าน brower เพื่อเข้าถึง Dapp

3. เป็น Dapp สำหรับการโหวต สามารถใส่ชื่อในตารางลงในช่องว่างเพื่อกดโหวต

Reference

- original content