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This is my Html code :

<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- The above 3 meta tags *must* come first in the head; any other head content must come *after* these tags -->
    <title>Election Results</title>

    <!-- Bootstrap -->
    <link href="css/bootstrap.min.css" rel="stylesheet">

    <!-- HTML5 shim and Respond.js for IE8 support of HTML5 elements and media queries -->
    <!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
    <!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/html5shiv/3.7.3/html5shiv.min.js"></script>
      <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
    <![endif]-->
  </head>
  <body>
    <div class="container" style="width: 650px;">
      <div class="row">
        <div class="col-lg-12">
          <h1 class="text-center">Election Results</h1>
          <hr/>
          <br/>
          <div id="loader">
            <p class="text-center">Loading...</p>
          </div>
          <div id="content" style="display: none;">
            <table class="table">
              <thead>
                <tr>
                  <th scope="col">#</th>
                  <th scope="col">Name</th>
                  <th scope="col">Votes</th>
                </tr>
              </thead>
              <tbody id="candidatesResults">
              </tbody>
            </table>
            <hr/>
            <form onSubmit="App.castVote(); return false;">
              <div class="form-group">
                <label for="candidatesSelect">Select Candidate</label>
                <select class="form-control" id="candidatesSelect">
                </select>
              </div>
              <button type="submit" class="btn btn-primary">Vote</button>
              <hr />
            </form>
            <p id="accountAddress" class="text-center"></p>
          </div>
        </div>
      </div>
    </div>

    <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
    <!-- Include all compiled plugins (below), or include individual files as needed -->
    <script src="js/bootstrap.min.js"></script>
    <script src="js/web3.min.js"></script>
    <script src="js/truffle-contract.js"></script>
    <script src="js/app.js"></script>
  </body>
</html>

I'm trying to connect my local blockchain on ganache to the app. I went to Metamask on chrome>Custom rpc enter image description here

But I'm not getting a desired result. It is not showing me the list of candidates. Can someone help? This is my Election.sol file

pragma solidity ^0.5.0;


contract Election {
    struct Candidate {
        uint id;
        string name;
        uint votecount;
    
    }
    
mapping (uint => Candidate) public candidates;
uint public candidateCount;

  constructor() public {
   addCandidate("Candidate 1");
   addCandidate("Candidate 2");
  }
  function addCandidate (string memory _name)  private {
    candidateCount++;
    candidates[candidateCount]=Candidate(candidateCount,_name,0);

  }

 
}

This is my app.js file:

  App = {
      web3Provider: null,
      contracts: {},
      account: '0x0',
      hasVoted: false,
    //initialise app using web3. It connects client side application to block chain
      init: function() {
        return App.initWeb3();
      },
    
      initWeb3: function() {
    
        if (typeof web3 !== 'undefined') {
          // If a web3 instance is already provided by Meta Mask.
          //Meta mask can change cgrome browser to metamask browser
          App.web3Provider = web3.currentProvider;
          //setting the web3 provider to our  own web3 provider
          web3 = new Web3(web3.currentProvider);
        } else {
          // Specify default instance if no web3 instance provided
          App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
          web3 = new Web3(App.web3Provider);
        }
        return App.initContract();
      },
    //initialise contract
    //contract to front end application
      initContract: function() {
    
        $.getJSON("Election.json", function(election)
        //load a new json file  of Election artifacts
         {
          // Instantiate a new truffle contract from the artifact
          //only the truffle contracts contacts inside the app
          App.contracts.Election = TruffleContract(election);
          // Connect provider to interact with contract
          App.contracts.Election.setProvider(App.web3Provider);
    
          App.listenForEvents();
          //make app work
          return App.render();
        });
      },
    
      // Listen for events emitted from the contract
      listenForEvents: function() {
        App.contracts.Election.deployed().then(function(instance) {
          // Restart Chrome if you are unable to receive this event
          // This is a known issue with Metamask
          // https://github.com/MetaMask/metamask-extension/issues/2393
          instance.votedEvent({}, {
            fromBlock: 0,
            toBlock: 'latest'
          }).watch(function(error, event) {
            console.log("event triggered", event)
            // Reload when a new vote is recorded
            App.render();
          });
        });
      },
    
      render: function() {
        //this display accounts of all acounts on blockchain
        //displays the candidates contesting
        var electionInstance;
        var loader = $("#loader");
        var content = $("#content");
    
        loader.show();
        content.hide();
    
        // Load account data
        //getCoinbase gives the account that we are currently on in the blockchain 
        web3.eth.getCoinbase(function(err, account) {
          if (err === null) {
            App.account = account;
            //display the account
            $("#accountAddress").html("Your Account: " + account);
          }
        });
    
        //get copy of deplyed contract
        App.contracts.Election.deployed().then(function(instance) {
          electionInstance = instance;
          return electionInstance.candidatesCount();
        }).then(function(candidatesCount) {
          var candidatesResults = $("#candidatesResults");
          candidatesResults.empty();
    
          var candidatesSelect = $('#candidatesSelect');
          candidatesSelect.empty();
    
          for (var i = 1; i <= candidatesCount; i++) {
            electionInstance.candidates(i).then(function(candidate) {
              var id = candidate[0];
              var name = candidate[1];
              var voteCount = candidate[2];
    
              // Render candidate Result
              var candidateTemplate = "<tr><th>" + id + "</th><td>" + name + "</td><td>" + voteCount + "</td></tr>"
              candidatesResults.append(candidateTemplate);
    
              // Render candidate ballot option
              var candidateOption = "<option value='" + id + "' >" + name + "</ option>"
              candidatesSelect.append(candidateOption);
            });
          }
          return electionInstance.voters(App.account);
        }).then(function(hasVoted) {
          // Do not allow a user to vote
          if(hasVoted) {
            $('form').hide();
          }
          loader.hide();
          content.show();
        }).catch(function(error) {
          console.warn(error);
        });
      },
    
      castVote: function() {
        var candidateId = $('#candidatesSelect').val();
        App.contracts.Election.deployed().then(function(instance) {
          return instance.vote(candidateId, { from: App.account });
        }).then(function(result) {
          // Wait for votes to update
          $("#content").hide();
          $("#loader").show();
        }).catch(function(err) {
          console.error(err);
        });
      }
    };
    
    $(function() {
      $(window).load(function() {
        //app initialises whenever 
        App.init();
      });
    });

This is what I'm getting: What i'm getting

This is what i should get: enter image description here

2
  • Can you add your app.js file ? – clement Dec 26 '20 at 21:54
  • @clement added the app.js file. Can you please explain the error in my code? – Vasvi Sood Dec 27 '20 at 5:19
0

Just refresh the page once. Metamask does not respond instantaneously. Also there were some variable name errors in the code (like using candidatesCount instead of Candidate), that I corrected.

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