I want to implement a swap on UniV3 but the follow error appears:
Gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending? execution reverted
I have approved the Weth via etherscan goerli so I don't know why is sending me this error.Any advice??
Here is the code:
// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity ^0.8.0;
pragma abicoder v2;
import '@uniswap/v3-periphery/contracts/interfaces/ISwapRouter.sol';
import '@uniswap/v3-periphery/contracts/libraries/TransferHelper.sol';
contract SwapExamples {
// For the scope of these swap examples,
// we will detail the design considerations when using `exactInput`, `exactInputSingle`, `exactOutput`, and `exactOutputSingle`.
// It should be noted that for the sake of these examples we pass in the swap router as a constructor argument instead of inheriting it.
// More advanced example contracts will detail how to inherit the swap router safely.
// This example swaps DAI/WETH9 for single path swaps and DAI/USDC/WETH9 for multi path swaps.
ISwapRouter public immutable swapRouter;
// Router = 0xE592427A0AEce92De3Edee1F18E0157C05861564
address public constant DAI = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
address public constant WETH = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6; //0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
address public constant USDC = 0xEEa85fdf0b05D1E0107A61b4b4DB1f345854B952;//0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
// For this example, we will set the pool fee to 0.3%.
uint24 public constant poolFee = 3000;
uint256 public UsdOut;
constructor(ISwapRouter _swapRouter) {
swapRouter = _swapRouter;
}
/// @notice swapExactInputSingle swaps a fixed amount of DAI for a maximum possible amount of WETH9
/// using the DAI/WETH9 0.3% pool by calling `exactInputSingle` in the swap router.
/// @dev The calling address must approve this contract to spend at least `amountIn` worth of its DAI for this function to succeed.
/// @param amountIn The exact amount of DAI that will be swapped for WETH9.
/// @return amountOut The amount of WETH9 received.
function swapExactInputSingle(uint256 amountIn) external returns (uint256 amountOut) {
// msg.sender must approve this contract
// TransferHelper.safeApprove(WETH, address(this), amountIn);
// Transfer the specified amount of DAI to this contract.
TransferHelper.safeTransferFrom(WETH, msg.sender, address(this), amountIn); //Envia de la wallet a aquest contract, no necessito.
// Approve the router to spend DAI.
TransferHelper.safeApprove(WETH, address(swapRouter), amountIn);
// Naively set amountOutMinimum to 0. In production, use an oracle or other data source to choose a safer value for amountOutMinimum.
// We also set the sqrtPriceLimitx96 to be 0 to ensure we swap our exact input amount.
ISwapRouter.ExactInputSingleParams memory params =
ISwapRouter.ExactInputSingleParams({
tokenIn: WETH,
tokenOut: USDC,
fee: poolFee,
recipient: msg.sender,
deadline: block.timestamp,
amountIn: amountIn,
amountOutMinimum: 0,
sqrtPriceLimitX96: 0
});
// The call to `exactInputSingle` executes the swap.
amountOut = swapRouter.exactInputSingle(params);
UsdOut = amountOut;
}
}