Buy specified token function

Support Contracts
1

Trying to do custom token buy function and there are no error given by remix while deploying when I try to execute this buy function it is given error

:1234: Code to reproduce

 function buy(uint _amount) external {
        address from = msg.sender;
        address to = address(this);
        uint256 amountTobuy = _amount;
        token.transferFrom(from, to, _amount);
       
    }

:computer: Environment

Remix

1 Like
2

There's not enough information provided. Is the user trying to buy directly from the ERC20 token contract? Or maybe it's like some auction contract?

Please share a bit more context on what you are trying to do.

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3

If I am right, the buy function should take "token" from msg.sender and receive in contract balance.
To use transferFrom you must first approve the contract on the token contract address on bscscan.

Let's suppose you want to take user's "CAKE" when he call buy().
The user have to:

  1. go on the write section of the token https://bscscan.com/token/0x0e09fabb73bd3ade0a17ecc321fd13a19e81ce82#writeContract

  2. connect metamask wallet to bscscan

  3. go here

    image
    image1513×288 4.21 KB

  4. "spender" is your contract address (where there is buy function). "amount" is the amount that the contract will take, it must include the decimals (ie. 100 CAKE = 100000000000000000000)

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4

Ok but where the contract address is given

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5 

interface IERC20 {
   
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


contract Vault {
  address public admin;
  IERC20 public token;
  event BuyPoint(uint pointt, address account);
  



  constructor(address _token, address _admin) {
    admin = _admin; 
    token = IERC20(_token);
  }

  function updateAdmin(address newAdmin) external {
    require(msg.sender == admin, 'only admin');
    admin = newAdmin;
  }
  
  function buy(uint _amount) external {
        address from = msg.sender;
        address to = address(this);
        uint256 amountTobuy = _amount;
        uint points = amountTobuy;
        token.transferFrom(from, to, _amount);
        emit BuyPoint(points, msg.sender);
    }

  function sellTokens(
    address recipient,
    uint _point
    
  ) public {
    
    uint amount = _point;
    token.transfer(recipient, amount);
    
  }


}```
1 Like
6

Your contract address is give once deployed

1 Like
7

I am trying to run the contract its getting deployed but giving error while running it

2 Likes