以 Truffle 教程为基础 - 添加返回宠物 Function - RPC 错误

Question

I'm building on top of the tutorial provided by Truffle here: https://trufflesuite.com/tutorial/index.html

I'm trying to add a returnPet function similar to: Adding a return function to Truffles Pet Shop

However, I'm running into an RPC error when using metamask when I click on the 'Return' button on a pet.

MetaMask - RPC Error: [ethjs-query] while formatting outputs from RPC '{"value":{"code":-32603,"data":{"message":"VM Exception while processing transaction: revert","code":-32000,"data":{"0x36735e441b9c6ffeb61bcebce098576993c38580ecc207f99043706a074a06e4":{"error":"revert","program_counter":70,"return":"0x"},"stack":"RuntimeError: VM Exception while processing transaction: revert\n    at Function.RuntimeError.fromResults (/tmp/.mount_ganachz4CZxO/resources/static/node/node_modules/ganache-core/lib/utils/runtimeerror.js:94:13)\n    at BlockchainDouble.processBlock (/tmp/.mount_ganachz4CZxO/resources/static/node/node_modules/ganache-core/lib/blockchain_double.js:627:24)\n    at runMicrotasks (<anonymous>)\n    at processTicksAndRejections (internal/process/task_queues.js:93:5)","name":"RuntimeError"}}}}' 
Object { code: -32603, message: "[ethjs-query] while formatting outputs from RPC '{\"value\":{\"code\":-32603,\"data\":{\"message\":\"VM Exception while processing transaction: revert\",\"code\":-32000,\"data\":{\"0x36735e441b9c6ffeb61bcebce098576993c38580ecc207f99043706a074a06e4\":{\"error\":\"revert\",\"program_counter\":70,\"return\":\"0x\"},\"stack\":\"RuntimeError: VM Exception while processing transaction: revert\\n    at Function.RuntimeError.fromResults (/tmp/.mount_ganachz4CZxO/resources/static/node/node_modules/ganache-core/lib/utils/runtimeerror.js:94:13)\\n    at BlockchainDouble.processBlock (/tmp/.mount_ganachz4CZxO/resources/static/node/node_modules/ganache-core/lib/blockchain_double.js:627:24)\\n    at runMicrotasks (<anonymous>)\\n    at processTicksAndRejections (internal/process/task_queues.js:93:5)\",\"name\":\"RuntimeError\"}}}}'" }

I'm maintaining this work here: https://github.com/mpoletiek/pet-shop-tutorial

I'm not sure where to begin. Before approving the transaction in Metamask, it warns:

This transaction is expected to fail. Trying to execute it is expected to be expensive but fail, and is not recommended.

I click 'I will try anyway' to generate the RPC error.

Here is my Solidity contract:

pragma solidity ^0.5.0;

contract Adoption {
    address[16] public adopters;

    // Adopting a pet
    function adopt(uint petId) public returns (uint) {
        require(petId >= 0 && petId <= 15);

        adopters[petId] = msg.sender;

        return petId;
    }

    // Retrieving the adopters
    function getAdopters() public view returns (address[16] memory) {
        return adopters;
    }
    
    // Return Pet
    function returnPet(uint petId) public returns (address) {
        require(petId >= 0 && petId <= 15);
        
        // Address must own the pet
        require(msg.sender == adopters[petId]);
        
        // Clear the adopter for this pet
        adopters[petId] = address(0);
        
        return adopters[petId];
    }

}

and app.js:

App = {
  web3Provider: null,
  accounts: [],
  contracts: {},
  adoptionInstance: null,

  init: async function() {
    // Load pets.
    $.getJSON('../pets.json', function(data) {
      var petsRow = $('#petsRow');
      var petTemplate = $('#petTemplate');

      for (i = 0; i < data.length; i ++) {
        petTemplate.find('.panel-title').text(data[i].name);
        petTemplate.find('img').attr('src', data[i].picture);
        petTemplate.find('.pet-breed').text(data[i].breed);
        petTemplate.find('.pet-age').text(data[i].age);
        petTemplate.find('.pet-location').text(data[i].location);
        petTemplate.find('.btn-adopt').attr('data-id', data[i].id);
        petTemplate.find('.btn-return').attr('data-id', data[i].id);

        petsRow.append(petTemplate.html());
      }
    });

    return await App.initWeb3();
  },

  initWeb3: async function() {

    // Modern dapp browsers...
    if (window.ethereum){
      try {
        //Request account access
        App.accounts = await window.ethereum.request({ method: "eth_requestAccounts" });
      } catch (error) {
        // User denied account access...
        console.error("User denied account access");
      }
      
      // User granted access to accounts
      console.log("Account[0]: "+App.accounts[0]);
      
      App.web3Provider = window.ethereum;
      console.log("modern dapp browser");
    }
    // Legacy dapp browsers...
    else if (window.web3) {
      App.web3Provider = window.web3.currentProvider;
      App.accounts = window.eth.accounts;
      console.log("legacy dapp browser");
    }
    // if no injected web3 instance is detected, fall back to Ganache
    else {
      App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
    }
    
    web3 = new Web3(App.web3Provider);

    return App.initContract();
    
  },

  initContract: function() {

    $.getJSON('Adoption.json', function(data) {
      // Get the necessary contract artifact file and instantiate it with @truffle/contract
      var AdoptionArtifact = data;
      try { App.contracts.Adoption = TruffleContract(AdoptionArtifact); } catch (error) { console.error(error); }

      // Set the provider for our contract
      try {
        App.contracts.Adoption.setProvider(App.web3Provider);
      } catch (error){
        console.log(error);
      }
      // Use our contract to retrieve and mark the adopted pets
      return App.markAdopted();
    });

    return App.bindEvents();
  },

  bindEvents: function() {
    $(document).on('click', '.btn-adopt', App.handleAdopt);
    $(document).on('click', '.btn-return', App.handleReturn);
  },

  markAdopted: function() {

    var adoptionInstance;

    App.contracts.Adoption.deployed().then(function(instance) {
      App.adoptionInstance = instance;

      return App.adoptionInstance.getAdopters.call();
    }).then(function(adopters) {
        
        for(i=0;i<adopters.length;i++){
            if (adopters[i] != '0x0000000000000000000000000000000000000000') {
                if (adopters[i] == App.accounts[0]){
                    $('.panel-pet').eq(i).find('.btn-return').text('Return').attr('disabled', false);
                    $('.panel-pet').eq(i).find('.btn-adopt').text('Adopted').attr('disabled', true);
                } else {
                    $('.panel-pet').eq(i).find('.btn-return').text('-').attr('disabled', true);
                    $('.panel-pet').eq(i).find('.btn-adopt').text('Adopted').attr('disabled', true);
                }
            } else {
                $('.panel-pet').eq(i).find('.btn-return').text('-').attr('disabled', true);
            }
        }
        
        
        
    }).catch(function(err) {
      console.log(err.message);
    });
  },

  handleReturn: function(event) {
    event.preventDefault();
    
    var petId = parseInt($(event.target).data('id'));
    
    console.log("petID:"+petId);
        
    App.contracts.Adoption.deployed().then(function(instance) {

        // Execute adopt as a transaction by sending account
        return App.adoptionInstance.returnPet(petId, {from: App.accounts[0]});
      }).then(function(result) {
        return App.markAdopted();
      }).catch(function(err) {
        console.log(err.message);
      });
    
  },


  handleAdopt: function(event) {
    event.preventDefault();

    var petId = parseInt($(event.target).data('id'));
    console.log("petId:"+petId);

    App.contracts.Adoption.deployed().then(function(instance) {

        // Execute adopt as a transaction by sending account
        return App.adoptionInstance.adopt(petId, {from: account[0]});
        }).then(function(result) {
            return App.markAdopted();
        }).catch(function(err) {
            console.log(err.message);
    });
    
  }

};

$(function() {
  $(window).load(function() {
    App.init();
  });
});

Everything compiles and my tests run okay. Not sure how Metamask knows the transaction is bad before I confirm, but is that a hint? I get the same result in Firefox and Chrome if that helps.

Any ideas what I should check first?

Thanks,

Answer 1

Based on the provided code, you're trying to return a pet that hasn't been yet adopted, so it fails on this logical error.

First you deploy the contract. Since there's no adoption mechanism in the constructor, there are no adopted pets after this step.

App.contracts.Adoption.deployed()

And immediately after that you're trying to return a pet

return adoptionInstance.returnPet

Which fails on this line, because all adopters have the default value 0x0 at this point.

require(msg.sender == adopters[petId]);

Solution : Based on the context of your JS code (the comment and return App.markAdopted() ), you probably wanted to invoke the adopt() function in the JS test - and not the returnPet() .

Answer 2

So I finally got this working after resetting my entire environment and rebuilding with truffle migrate --reset . I also had to ensure I only had 1 browser tab open to the app, multiple tabs resulted in multiple transactions for some reason I'm still unaware of.

app.js

App = {
  web3Provider: null,
  accounts: [],
  contracts: {},

  init: async function() {
    // Load pets.
    $.getJSON('../pets.json', function(data) {
      var petsRow = $('#petsRow');
      var petTemplate = $('#petTemplate');

      for (i = 0; i < data.length; i ++) {
        petTemplate.find('.panel-title').text(data[i].name);
        petTemplate.find('img').attr('src', data[i].picture);
        petTemplate.find('.pet-breed').text(data[i].breed);
        petTemplate.find('.pet-age').text(data[i].age);
        petTemplate.find('.pet-location').text(data[i].location);
        petTemplate.find('.btn-adopt').attr('data-id', data[i].id);
        petTemplate.find('.btn-return').attr('data-id', data[i].id);

        petsRow.append(petTemplate.html());
      }
    });

    return await App.initWeb3();
  },

  initWeb3: async function() {

    // Modern dapp browsers...
    if (window.ethereum){
      try {
        //Request account access
        App.accounts = await window.ethereum.request({ method: "eth_requestAccounts" });
      } catch (error) {
        // User denied account access...
        console.error("User denied account access");
      }
      
      // User granted access to accounts
      console.log("Account[0]: "+App.accounts[0]);
      
      App.web3Provider = window.ethereum;
      console.log("modern dapp browser");
    }
    // Legacy dapp browsers...
    else if (window.web3) {
      App.web3Provider = window.web3.currentProvider;
      App.accounts = window.eth.accounts;
      console.log("legacy dapp browser");
    }
    // if no injected web3 instance is detected, fall back to Ganache
    else {
      App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
    }
    
    //web3 = new Web3(App.web3Provider);

    return App.initContract();
    
  },

  initContract: function() {

    $.getJSON('Adoption.json', function(data) {
      // Get the necessary contract artifact file and instantiate it with @truffle/contract
      var AdoptionArtifact = data;
      try { App.contracts.Adoption = TruffleContract(AdoptionArtifact); } catch (error) { console.error(error); }

      // Set the provider for our contract
      try {
        App.contracts.Adoption.setProvider(App.web3Provider);
      } catch (error){
        console.log(error);
      }
      // Use our contract to retrieve and mark the adopted pets
      return App.markAdopted();
    });

    return App.bindEvents();
  },

  bindEvents: function() {
    $(document).on('click', '.btn-adopt', App.handleAdopt);
    $(document).on('click', '.btn-return', App.handleReturn);
  },

  markAdopted: function() {

    var adoptionInstance;
    App.contracts.Adoption.deployed().then(function(instance) {
      adoptionInstance = instance;

      return adoptionInstance.getAdopters.call();
    }).then(function(adopters) {
        
        for(i=0;i<adopters.length;i++){
            if (adopters[i] != '0x0000000000000000000000000000000000000000') {
                if (adopters[i] == App.accounts[0]){
                    $('.panel-pet').eq(i).find('.btn-return').text('Return').attr('disabled', false);
                    $('.panel-pet').eq(i).find('.btn-adopt').text('Adopted').attr('disabled', true);
                } else {
                    $('.panel-pet').eq(i).find('.btn-return').text('-').attr('disabled', true);
                    $('.panel-pet').eq(i).find('.btn-adopt').text('Adopted').attr('disabled', true);
                }
            } else {
                $('.panel-pet').eq(i).find('.btn-return').text('-').attr('disabled', true);
            }
        }

        
    }).catch(function(err) {
      console.log(err.message);
    });
  },

  handleReturn: function(event) {
    event.preventDefault();
    
    var petId = parseInt($(event.target).data('id'));
    
    console.log("handleReturn petId: "+petId+" Account[0]: "+App.accounts[0]);
    console.log("petID:"+petId);
    console.log("Account[0]: "+App.accounts[0]);
    
    var adoptionInstance;
    App.contracts.Adoption.deployed().then(function(instance) {
      adoptionInstance = instance;

      return adoptionInstance.returnPet(petId, {from: App.accounts[0]});
    }).then(function(result){
        App.markAdopted();
    });
    
  },


  handleAdopt: function(event) {
    event.preventDefault();

    var petId = parseInt($(event.target).data('id'));
    console.log("handleAdopt petId: "+petId+" Account[0]: "+App.accounts[0]);
    console.log("petId:"+petId);

    var adoptionInstance;
    App.contracts.Adoption.deployed().then(function(instance) {
      adoptionInstance = instance;

      return adoptionInstance.adopt(petId, {from: App.accounts[0]});
    }).then(function(result){
        App.markAdopted();
    });
    
  }

};

$(function() {
  $(window).load(function() {
    App.init();
  });
});

Adoption.sol

pragma solidity ^0.5.0;

contract Adoption {
    address[16] public adopters;

    // Adopting a pet
    function adopt(uint petId) public returns (uint) {
        require(petId >= 0 && petId <= 15);

        adopters[petId] = msg.sender;

        return petId;
    }

    // Retrieving the adopters
    function getAdopters() public view returns (address[16] memory) {
        return adopters;
    }
    
    // Return Pet
    function returnPet(uint petId) public returns (uint) {
        require(petId >= 0 && petId <= 15);
        
        // Address must own the pet
        require(msg.sender == adopters[petId]);
        
        // Clear the adopter for this pet
        adopters[petId] = address(0);
        
        return petId;
    }

}