"Not Enough Fund" when doing buying token transaction in Solidity with Remix IDE - ethereum

Question

I am completely new to this blockchain world so I want to try learn it. While I am following a tutorial to create a simple ERC-1155 contract to mint a token and set its price. When I am trying to run the buyToken function from another address, it keeps saying "Not Enough Fund". When I debug the msg.value value is 0, even though I have 100 ethers balance on each of my address. When I change the amount of token to 0, it works successfully. What should I need to do to be able to do the transaction?
Log
This is my contract that I have modified on:
// Contract based on https://docs.openzeppelin.com/contracts/4.x/erc1155
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "#openzeppelin/contracts/token/ERC1155/ERC1155.sol";
/**
* #title NFTMinter
* #dev NFT Contract Minter
* #custom:dev-run-script ./scripts/deploy_with_ethers.ts
*/
contract NFTMinter is ERC1155 {
constructor() ERC1155("https://raw.githubusercontent.com/noopmood/TutorialNFTInGo/main/metadata/{id}.json") payable {}
// Define the mapping of addresses to balances
mapping(address => mapping(uint256 => uint256)) public _balances;
// Define the mapping of address to tokenIds owned
mapping(address => uint256[]) public _tokenIds;
// Define the mapping of tokenId to price
mapping(uint256 => uint256) public tokenPrice;
// Define the sender to address payable type
address payable public sender;
struct Token {
uint256 tokenId;
uint256 balance;
}
function mintCaller(uint256 tokenId, uint256 amount) public {
_mint(msg.sender, tokenId, amount, "");
}
// Mints new tokens and sets the price for each token.
function mintAddress(uint256 tokenId, uint256 amount, address addr, uint256 price) public{
_mint(addr, tokenId, amount, "");
// Update the balance of the recipient
_balances[addr][tokenId] += amount;
// Add the tokenId to the address
_tokenIds[addr].push(tokenId);
// Set the price of the token
tokenPrice[tokenId] = price;
}
// Get all tokenIds from its owner address
function getTokenIdsByAddress(address addr) public view returns (uint[] memory) {
return _tokenIds[addr];
}
// Get the balance / amount of the tokenId
function getTokenByIdAndAddress(address addr, uint256 tokenId) public view returns (Token memory) {
Token memory result;
result.tokenId = tokenId;
result.balance = _balances[addr][tokenId];
return result;
}
// Get the tokenIds along with its corresponding balances/amount
function getAllTokenByAddress(address holder) public view returns (Token[] memory) {
Token[] memory result = new Token[](_tokenIds[holder].length);
for (uint i = 0; i < _tokenIds[holder].length; i++) {
result[i].tokenId = _tokenIds[holder][i];
result[i].balance = _balances[holder][_tokenIds[holder][i]];
}
return result;
}
// Transfers the tokens from one address to another.
function transfer(address addr, uint256 tokenId, uint256 amount) public {
require(_balances[msg.sender][tokenId] >= amount, "Not enough balance");
// Transfer the token
_safeTransferFrom(msg.sender, addr, tokenId, amount, "");
// Update the sender's balance
_balances[msg.sender][tokenId] -= amount;
// Update the recipient's balance
_balances[addr][tokenId] += amount;
}
// Allows a buyer to purchase a token by sending the required amount to the contract and updating the balance of the buyer.
function buyToken(uint256 tokenId, uint256 amount) public payable {
require(msg.value >= amount * tokenPrice[tokenId], "Not enough funds");
// Deduct the amount from the buyer
sender = payable(msg.sender);
sender.transfer(amount * tokenPrice[tokenId]);
// Transfer the token to the buyer
_safeTransferFrom(address(0), msg.sender, tokenId, amount, "");
// Update the buyer's balance
_balances[msg.sender][tokenId] += amount;
}
}
On what the step to reproduce this:
Deploy the contract with value, for me I pass 20 Ether
Run the mintAddress function by passing, tokenId: 1, amount: 10, price: 10, address: the address an account
Run the transfer function by passing address: the address of account you want to transfer the token into, tokenId: 1, amount: 10
Change the account in upper part to the address you use in transfer function
Run buyToken function, tokenId: 1, amount: 10
It will said Not Enough Fund
buyToken
What I have tried so far:
I read in another post, that I should deploy the contract with the value in it. But it still doesn't work
I have checked that the balance of my account in remix have 100 ethers, but when I try to doing the buy token with it, it still said 'Not Enough Fund'
What I am expecting:
To be able to buy the token with the price that has been set when minting the token.

Answer 1

Your error is failing from here:
// require is like if statement. if condition does not satisfied, it shows the passed message
require(msg.value >= amount * tokenPrice[tokenId], "Not enough funds")
When a user sends funds alongside the transaction, not as an function argument, solidity will catch it with msg.value. Looks like you are not sending any value alongside the transaction or not sending enough funds. in Remix IDE
you need to pass the necessary value in the above red borderd box