TransferHelper: TRANSFER_FROM_FAILED unable to swap token to token uniswap

Question

I am trying to swap using WETH from my contract to DAI using swapExactTokensForTokens(amountIn, amountOutMin, getPathForETHtoToken(tokenAddress), address(this), deadline) with uniswap. First I approved large amount on both DAI and WETH address then I deposited 0.01 worth of WETH using:

function wrap() public payable restricted {
    if (msg.value != 0) {
      WETH.deposit{value : msg.value}();
      WETH.transfer(address(this), msg.value);
    }
  }

on my contract and now able to see the balance in WETH Next on remix I filled out the parameters for my swap function

function Buy(uint amountIn, uint amountOutMin, uint deadline, address tokenAddress) external payable restricted {
    uniswapRouter.swapExactTokensForTokens(amountIn, amountOutMin, getPathForETHtoToken(tokenAddress), address(this), deadline);
}

// amountIn = 10000000000000000, amountOutMin = 4029840000000000000, etc

And when I execute I get this error

Fail with error 'TransferHelper: TRANSFER_FROM_FAILED'

How do I resolve this issue?

Answer 1

In my case I had to call approve on the from token again, just before calling swap