Hey I have just created a Decentralised Lottery. I have integrated it with front-end. I have a function to fetch which is minimumContribution. It was working fine when a user logs in with metamask but when the user hits the refresh button of the webpage the value automatically sets to 0. Can anyonehelp!
//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.7;
contract Lottery{
uint private trackMappping;
mapping(uint256=>mapping(address=>uint256)) private trackPlayers;
address public manager;
uint256 private immutable minContribution;
address[] private players;
event playerEntry(address indexed player);
event winnerPicked(address indexed winner);
bool public isOpen=true;
constructor(uint256 _amount){
minContribution=_amount;
manager=msg.sender;
}
function enterLottery() public payable{
if(msg.value<=minContribution){
revert("your value is less than minimium contribution");
}else if(!isOpen){
revert("Lottery is closed");
}
else if(trackPlayers[trackMappping][msg.sender]==0){
players.push(msg.sender);
}
trackPlayers[trackMappping][msg.sender]+=msg.value;
emit playerEntry(msg.sender);
}
function getminContribution()public view returns(uint256){
require(isOpen, "Lottery Closed!");
return minContribution;
}
function random() internal view returns(uint){
return uint(keccak256(abi.encodePacked(block.difficulty, block.timestamp, players.length)));
}
function pickWinner()public{
require(isOpen,"Lottery has been closed");
require(msg.sender==manager,"You aren't the manager of this smart contract");
require(players.length>3,"Can't declare winner with less than 4 players");
uint count=random();
uint winner=count%players.length;
(bool success,)=payable(players[winner]).call{value:address(this).balance}("");
if(!success){
revert("Transfer failed due to some error");
}
emit winnerPicked(players[winner]);
delete players;
trackMappping++;
isOpen=false;
}
function getBalance() public view returns (uint256){
require(isOpen,"Lottery has been closed");
return address(this).balance;
}
function getParticipants()public view returns(uint256){
require(isOpen,"Lottery has been closed");
return players.length;
}
function startLottery() public{
require(msg.sender==manager,"You aren't the manager of this smart contract");
isOpen=true;
}
}
My front-end code-
import {useMoralis} from "react-moralis";
import swal from 'sweetalert';
import React from "react";
function App() {
const ABI= [{"inputs":[{"internalType":"uint256","name":"_amount","type":"uint256"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"player","type":"address"}],"name":"playerEntry","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"winner","type":"address"}],"name":"winnerPicked","type":"event"},{"inputs":[],"name":"enterLottery","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"getBalance","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"getParticipants","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"getminContribution","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"isOpen","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"manager","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"pickWinner","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"startLottery","outputs":[],"stateMutability":"nonpayable","type":"function"}]
const[par, setPar]=React.useState(0);
const[bal, setBal]=React.useState(0);
const[min, setMin]=React.useState(0);
const[status, setStatus]=React.useState(false);
const {authenticate, isAuthenticated, isAuthenticating, user, account, logout}=useMoralis();
const {Moralis} = useMoralis();
async function login(){
if(!isAuthenticated){
await authenticate();
}
lotteryStatus();
minContribution();
}
async function exit(){
await logout();
}
async function enterLottery(){
const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "enterLottery",
abi: ABI,
msgValue: await Moralis.Units.ETH(prompt("Enter the amount in ETH:"))
}
const transaction = await Moralis.executeFunction(sendOptions);
}
async function minContribution(){
// const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "getminContribution",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
setMin(Moralis.Units.FromWei(transaction._hex));
}
async function pickWinner(){
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "pickWinner",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
setStatus(false);
}
async function getBalance(){
const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "getBalance",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
setBal(Moralis.Units.FromWei(transaction._hex));
}
async function getParticipants(){
//const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "getParticipants",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
swal({
title: `Participants: ${Moralis.Units.FromWei(transaction._hex, 0)}`,
icon: "info",
});
}
async function showInfo(){
const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "getParticipants",
abi: ABI
}
const lists = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "getBalance",
abi: ABI
}
const participants = await Moralis.executeFunction(sendOptions);
const balances=await Moralis.executeFunction(lists);
swal({
title: `Participants: ${Moralis.Units.FromWei(participants._hex, 0)}`,
text: `Balance: ${Moralis.Units.FromWei(balances._hex)}`,
icon: "info",
});
}
async function startLottery(){
// const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "startLottery",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
setStatus(true);
}
async function lotteryStatus(){
// const web3 = await Moralis.enableWeb3({ provider: "metamask" });
const sendOptions = {
contractAddress: "0x8d61466b42308fc259E875Fe71Fe173555F8731A",
functionName: "isOpen",
abi: ABI
}
const transaction = await Moralis.executeFunction(sendOptions);
setStatus(transaction);
}
return (
<>
<div className="card text-center bg2" >
<div className="card-body bg2" >
{/* {isAuthenticated? <button type="button" className="btn btn-outline-warning" onClick={Update}>Balance: {balances}</button> : null} */}
{isAuthenticated? <p className="lottery">Lottery : {status? "Running": "Closed"}</p> : <p className="lottery">Lottery</p>}
{isAuthenticated? <p className=" text-gradient">Account : {user.get("ethAddress")}</p> : <p className=" text-gradient">Account : Not Connected</p>}
{isAuthenticated? <p className=" text-gradient">{null}</p> : null}
{isAuthenticated? <p className="min">Minimum Contribution : {min} ETH</p> : null}
{isAuthenticated? <button className="button-custom" onClick={showInfo}>INFO</button> : null}
{!isAuthenticated? <button type="button" className="btn btn-outline-light button-85" onClick={login}>
Connect to metamask
</button> : null}
{isAuthenticated? <button type="button" className="button-33" onClick={enterLottery} >Enter Lottery</button> : null}
{(isAuthenticated && user.get('ethAddress')==="0x846A519f8c6ceF4db5ABa30Fc3c36BE38DA48F06".toLowerCase())? <button type="button" className="btn btn-outline-success" onClick={startLottery}>Start Lottery</button> : null}
{(isAuthenticated && user.get('ethAddress')==="0x846A519f8c6ceF4db5ABa30Fc3c36BE38DA48F06".toLowerCase())? <button type="button" className="btn btn-outline-primary" onClick={pickWinner}>Pick Winner</button> : null}
{isAuthenticated?<button type="button" className="button-78" onClick={exit}>Logout</button> : null}
</div>
<div className="card-footer text-gradient">Copyright @Abir Dutta</div>
</div>
</>
);
}
export default App;
Please review it once.
This project is hosted- https://deadmanabir.github.io/Lottery/ ](https://deadmanabir.github.io/Lottery/
