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I was deploying a NFT and the VRF coordinator takes too much time to respond and I cant see if the _safemint function is working or not. Also i cant verify the contract on rinkeby.io Is there a way to read some variables from a deployed on chain contract ?

Advanced collectible.sol :

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@chainlink/contracts/src/v0.6/VRFConsumerBase.sol";

contract AdvancedCollectible is ERC721, VRFConsumerBase{
    uint256 public tokenCounter;
    bytes32 public keyhash;
    uint256 public fee;
    enum Breed{CAT1, CAT2, NFT1, NFT2}
    mapping(uint256 => Breed) public tokenIdToBreed;
    mapping(bytes32 => address) public requestIdToSender;
    event requestedCollectible(bytes32 indexed requestId, address requester);
    event breedAssigned(uint256 indexed tokenId, Breed breed);

    constructor(address _vrfCoordinator, address _linkToken, bytes32 _keyhash, uint256 _fee) public
    VRFConsumerBase(_vrfCoordinator, _linkToken)
    ERC721("Dogie", "NFT")
    {
        tokenCounter = 0;
        keyhash = _keyhash;
        fee = _fee;
    }

    function createCollectible() public returns (bytes32){
        bytes32 requestId = requestRandomness(keyhash, fee);
        requestIdToSender[requestId] = msg.sender;
        emit requestedCollectible(requestId, msg.sender);
        // tokenCounter = tokenCounter + 2;
    }

    function fulfillRandomness(bytes32 requestId, uint256 randomNumber) internal override {
        Breed breed = Breed(randomNumber % 4);
        uint256 newTokenId = tokenCounter;
        tokenIdToBreed[newTokenId] = breed;
        emit breedAssigned(newTokenId, breed);
        address owner = requestIdToSender[requestId];
        _safeMint(owner, newTokenId);
        tokenCounter = tokenCounter + 1;
        
    }

    function setTokenURI(uint256 tokenId, string memory _tokenURI) public {
        // 11:10:43 / 16:22:11   
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not owner no approved");
        _setTokenURI(tokenId, _tokenURI);
    }
}

deploy_and_create.py:

import time import brownie from scripts.helpful_scripts2 import fund_with_link, get_account, OPENSEA_URL, get_contract from brownie import AdvancedCollectible, config, network

def deploy_and_create():
    account = get_account()
    
    
    # print(get_contract('vrf_coordinator'))
    advanced_collectible = AdvancedCollectible.deploy(
        get_contract('vrf_coordinator'),
        get_contract('link_token'),
        config['networks'][network.show_active()]['keyhash'],
        config['networks'][network.show_active()]['fee'],
        {"from":account})
    
    fund_with_link(advanced_collectible)
    creating_tx = advanced_collectible.createCollectible({"from":account})
    creating_tx.wait(1)
    print('Do not try to sleep!')
    # time.sleep(1)
    print(f'New token has been created!  ≧◠‿◠≦✌, {advanced_collectible.tokenCounter()}') # It prints 0 every time

    return advanced_collectible, creating_tx


def main():
    deploy_and_create() 
Any help will be appriciated
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  • Alright, so you want to read a variable value from a deployed contract? It's possible, but only if the variable is public. (Private variables can be read too, but that is more complex).
    – Sky
    May 30, 2022 at 11:26
  • i cant verify the contract on rinkeby.io -> when you use "^" in your contract then you have this problem. use always a specific solidity compiler version and a specific version of openzeppelin
    – Majd TL
    May 30, 2022 at 11:33

1 Answer 1

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Yeah, you can read variables from the deployed contract. (Will work for public variable)

Example for brownie:

contractName.variableName() 

Or in your case:

AdvancedCollectible.tokenCounter()
AdvancedCollectible.keyhash()
AdvancedCollectible.fee()

I often do this in brownie tests where I have to assert the value of a variable. For example, I set fee to be 1000 then:

assert 1000 == AdvancedCollectible.fee()
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