Need help with transferring erc20 tokens from a user to smart contract [duplicate]

Question

I am using the following code to transfer some erc20 tokens with token address = token and amount being amount but every time I deploy it and try to transfer an erc20 token it is showing me the following error

Gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending? execution reverted: ERC20: insufficient allowance { "originalError": { "code": 3, "data": "0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001d45524332303a20696e73756666696369656e7420616c6c6f77616e6365000000", "message": "execution reverted: ERC20: insufficient allowance" } }

CODE:

function depositERC20tokens(address token, uint amount) public{
 

       IERC20 _token = IERC20(token);
        address me = address(this);
        uint256 allowance = _token.allowance(msg.sender,me);
        _token.approve(me,amount);
        _token.transferFrom(msg.sender, me, amount);
    }

Answer 1

your _token.approve(me,amount) is wrong, it will set allowance of your contract to spend token, while you need to set allowance of msg.sender to spend token.

function depositERC20tokens(address token, uint amount) public{
        IERC20 _token = IERC20(token);
        address me = address(this);
        address receiver = msg.sender;
        // uint256 allowance = _token.allowance(msg.sender,me);
        // _token.approve(me,amount);
        _token.approve(receiver, amount);
        _token.transferFrom(receiver, me, amount);
    }