# Mint a new position ### Input Parameters To mint a new position, we use the `nonFungiblePositionManager` and call `mint`. For this exact example, we’re hard-coding the token amounts to be minted. In production, this would be a user-configurable function argument. ```solidity /// @notice Calls the mint function defined in periphery, mints the same amount of each token. For this example we are providing 1000 DAI and 1000 USDC in liquidity /// @return tokenId The id of the newly minted ERC721 /// @return liquidity The amount of liquidity for the position /// @return amount0 The amount of token0 /// @return amount1 The amount of token1 function mintNewPosition() external returns ( uint256 tokenId, uint128 liquidity, uint256 amount0, uint256 amount1 ) { // For this example, we will provide equal amounts of liquidity in both assets. // Providing liquidity in both assets means liquidity will be earning fees and is considered in-range. uint256 amount0ToMint = 1000; uint256 amount1ToMint = 1000; ``` ### Calling Mint Here we approve the `nonfungiblePositionManager` to use the contracts' tokens, then populate the `MintParamsv struct and assign it to a local variable` params`that will be passed to the`nonfungiblePositionManager`when we call`mint\`. * By using `TickMath.MIN_TICK` and `TickMath.MAX_TICK`, we are providing liquidity across the whole pool’s range. In production, you may want to specify a more concentrated position. * We set `amount0Min` and `amount1Min` to zero for the example - but this would be a vulnerability in production. A function calling `mint` with no slippage protection would be vulnerable to a front running attack designed to execute the `mint` call at an inaccurate price. * For more reliable practice, the developer needs to implement a slippage assessment process. * Note that this function will not initialize a pool where one does not yet exist. ```solidity // Approve the position manager TransferHelper.safeApprove(DAI, address(nonfungiblePositionManager), amount0ToMint); TransferHelper.safeApprove(USDC, address(nonfungiblePositionManager), amount1ToMint); INonfungiblePositionManager.MintParams memory params = INonfungiblePositionManager.MintParams({ token0: DAI, token1: USDC, tickLower: TickMath.MIN_TICK, tickUpper: TickMath.MAX_TICK, amount0Desired: amount0ToMint, amount1Desired: amount1ToMint, amount0Min: 0, amount1Min: 0, recipient: address(this), deadline: block.timestamp }); // Note that the pool defined by DAI/USDC must already be created and initialized in order to mint (tokenId, liquidity, amount0, amount1) = nonfungiblePositionManager.mint(params); ``` ### Updating The Deposit Mapping And Refunding The Calling Address After the previous point, we can call the internal function we previously wrote in Setting Up Your Contract. After that, we can take any liquidity leftover from minting and refund it to `msg.sender`. ```solidity // Create a deposit _createDeposit(msg.sender, tokenId); // Remove allowance and refund in both assets. if (amount0 < amount0ToMint) { TransferHelper.safeApprove(DAI, address(nonfungiblePositionManager), 0); uint256 refund0 = amount0ToMint - amount0; TransferHelper.safeTransfer(DAI, msg.sender, refund0); } if (amount1 < amount1ToMint) { TransferHelper.safeApprove(USDC, address(nonfungiblePositionManager), 0); uint256 refund1 = amount1ToMint - amount1; TransferHelper.safeTransfer(USDC, msg.sender, refund1); } } ``` ### The Full Example ```solidity /// @notice Calls the mint function defined in periphery, mints the same amount of each token. For this example we are providing 1000 DAI and 1000 USDC in liquidity /// @return tokenId The id of the newly minted ERC721 /// @return liquidity The amount of liquidity for the position /// @return amount0 The amount of token0 /// @return amount1 The amount of token1 function mintNewPosition() external returns ( uint256 tokenId, uint128 liquidity, uint256 amount0, uint256 amount1 ) { // For this example, we will provide equal amounts of liquidity in both assets. // Providing liquidity in both assets means liquidity will be earning fees and is considered in-range. uint256 amount0ToMint = 1000; uint256 amount1ToMint = 1000; // Approve the position manager TransferHelper.safeApprove(DAI, address(nonfungiblePositionManager), amount0ToMint); TransferHelper.safeApprove(USDC, address(nonfungiblePositionManager), amount1ToMint); INonfungiblePositionManager.MintParams memory params = INonfungiblePositionManager.MintParams({ token0: DAI, token1: USDC, tickLower: TickMath.MIN_TICK, tickUpper: TickMath.MAX_TICK, amount0Desired: amount0ToMint, amount1Desired: amount1ToMint, amount0Min: 0, amount1Min: 0, recipient: address(this), deadline: block.timestamp }); // Note that the pool defined by DAI/USDC must already be created and initialized in order to mint (tokenId, liquidity, amount0, amount1) = nonfungiblePositionManager.mint(params); // Create a deposit _createDeposit(msg.sender, tokenId); // Remove allowance and refund in both assets. if (amount0 < amount0ToMint) { TransferHelper.safeApprove(DAI, address(nonfungiblePositionManager), 0); uint256 refund0 = amount0ToMint - amount0; TransferHelper.safeTransfer(DAI, msg.sender, refund0); } if (amount1 < amount1ToMint) { TransferHelper.safeApprove(USDC, address(nonfungiblePositionManager), 0); uint256 refund1 = amount1ToMint - amount1; TransferHelper.safeTransfer(USDC, msg.sender, refund1); } } ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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