just like the title says I cannot get using Strings to compile, I keep getting the identifier not found.
This is the start of my .sol contract
import "#openzeppelin/contracts-upgradeable/token/ERC721/extensions/ERC721EnumerableUpgradeable.sol";
import "#openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "#openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "#openzeppelin/contracts-upgradeable/utils/StringsUpgradeable.sol";
contract NFT is Initializable, StringsUpgradeable, ERC721EnumerableUpgradeable, OwnableUpgradeable {
using Strings for uint256;
Please help!
Thank you!
The imported StringsUpgradeable.sol file contains a library named StringsUpgradeable - not Strings.
Also, since it's a library, it cannot be inherited from, so you need to remove it from the list of the NFT parents.
pragma solidity ^0.8;
import "#openzeppelin/contracts-upgradeable/token/ERC721/extensions/ERC721EnumerableUpgradeable.sol";
import "#openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "#openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "#openzeppelin/contracts-upgradeable/utils/StringsUpgradeable.sol";
// removed `StringsUpgradable` from the parents list
contract NFT is Initializable, ERC721EnumerableUpgradeable, OwnableUpgradeable {
// replaced `Strings` to `StringsUpgradable`
using StringsUpgradeable for uint256;
}
Related
How to check values of a variables and functions in solidity like javascript via console.log? Because i need visibility of results for deep understanding.
I am newbie...
i tried hardhat but need more understand.
I'm a newbie too, but I know this (I think)!
There is no console in solidity, you need to write a function for this, or just put it public in the variable itself!
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
contract Value {
uint public num; //add "public" to see the value
function add(uint _num) external{
num += _num;
}
//this function is for returning value
function viewNum() public view returns(uint){
return(num);
}
}
Also use the Remix editor, it's in the browser. There are plenty of videos on the internet!
If you are using hardhat, then you can use console.sol.
You need to import it into your contract.
import "hardhat/console.sol";
Now, you are able to log your variable while you are working.
console.log(__your_variable__);
If you are still looking to log your variables once you deploy your contract, then you need to use event functionality.
Import hardhat console:
import "hardhat/console.sol";
Use console log in your contract
console.log(variable); //Variable value
console.log(1234); //direct value
I'm trying to wrap Eth from an smart contract as I want to swap weth later in uniswap but I don't know how to import the WETH code from goerli scan WETH = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6;.
Following internet examples I accomplished wrapping Eth but all influencers just import a ERC20 library to create a new one. I don't understand why they are using this as they are not interacting with the right weth contract.
Here is the code I used but is just creating a new token. Can anyone give me some advice?
// 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';
import '#openzeppelin/contracts/token/ERC20/ERC20.sol';
contract SwapExamples is ERC20 {
// 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;
address payable [] private s_Wallets;
uint256 public walletA = address(this).balance;
// Router = 0xE592427A0AEce92De3Edee1F18E0157C05861564
address public constant WETH = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6; //0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
// For this example, we will set the pool fee to 0.3%.
uint24 public constant poolFee = 3000;
uint256 public UsdOut;
constructor(ISwapRouter _swapRouter) ERC20("Wrapped Ether", "WETH") {//ERC20("Wrapped Ether", "WETH")
swapRouter = _swapRouter;
}
function Deposit() public payable {
s_Wallets.push(payable(msg.sender));
}
function Mint() external payable {
_mint(address(this), address(this).balance);
}
}
You need not create a new ERC20 token.
Calling:
WETH.deposit.value(msg.value)();
helps you wrap your ETH and you don't need to import WETH code from anywhere.
After wrapping, you can then move on to swapping WETH for any other token on Uniswap like you said.
I am doing the Solidity, Blockchain, and Smart Contract Course – Beginner to Expert Python Tutorial from freeCodeCamp and Patrick AlphaC
https://github.com/PatrickAlphaC/storage_factory
Below is my code image from my IDE too here
// SPDX-License_Identifier: MIT
pragma solidity ^0.8.0;
import "./SimpleStorage.sol";
contract StorageFactory {
SimpleStorage[] public simpleStorageArray;
function createSimpleStorageContact() public {
SimpleStorage simpleStorage = new SimpleStorage();
simpleStorageArray.push(simpleStorage);
}
}
and I am getting the error:
not found contracts/SimpleStorage.sol
even though all the files are spelt correctly and in the same folder.
Please help as I am trying to follow along with the tutorial and don't want to get left behind.
In your picture your filename is wrong. You write SimpleSorage but it must be SimpleStorage. (Note the missing t in Storage.)
getting an Invalid input source specified error with the following import when building a smart contract using the remix IDE
import "https://github.com/aave/flashloan-box/blob/Remix/contracts/aave/FlashLoanReceiverBase.sol";
Put together a super basic example smart contract in remix. It compiles just fine if I dont include the import statement.
pragma solidity ^0.6.6;
import "https://github.com/aave/flashloan-box/blob/Remix/contracts/aave/FlashLoanReceiverBase.sol";
contract Inbox {
string public message;
constructor(string memory initialMessage) public {
message = initialMessage;
}
function setMessage(string memory newMessage) public {
message = newMessage;
}
function getMessage() public view returns (string memory) {
return message;
}
}
This issue is happening because of the nested import using relative path.
The FlashLoanReceiverBase.sol is trying to import relative path ./IFlashLoanReceiver.sol (not absolute path https://github.com/aave/flashloan-box/blob/Remix/contracts/aave/IFlashLoanReceiver.sol).
Since you don't have a contract named IFlashLoanReceiver.sol in the same folder as your own contract, this import fails.
Best solution would be to submit a PR to the aave/flashloan-box repository making all import paths absolute.
This has been a problem I've been dealing with for a while now. My temporary solution has been to create a SafeMath.sol file in my Contracts directory and directly import it from there. However, I've been looking for a 'clearer solution' to this... Old way seemed to be directly importing it from a GitHub link, as seen in some repos and other stack overflow posts like such
However, the proper way do this seems to be installing the corresponding oz package (#openzeppelin/contracts-ethereum-package) and importing the file directly into the needed contract i.e.
import "#openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
However, using VSCode, I still get the error Source "#openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol" not found: File import callback not supported
That said, how can I properly import SafeMath?
EDIT: I am using pragma solidity ^0.6.0;
I looked through the node_modules for the package #openzeppelin/contracts. Here is the current correct import path as of posting:
import "#openzeppelin/contracts/utils/math/SafeMath.sol";
This is no longer needed with Solidity version 8
path is different in v 3.0 documentation
I used this:
import "#openzeppelin/contracts/math/SafeMath.sol";
Instead of this:
import "#openzeppelin/contracts/utils/math/SafeMath.sol";
Can be used in the following way:
pragma solidity ^0.5.0;
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v2.3.0/contracts/math/SafeMath.sol";
contract contractForSafeMath {
using SafeMath for uint;
uint256 addResult;
uint256 subResult;
uint256 mulResult;
uint256 divResult;
uint256 modResult;
uint public MAX_VALUE = 2**256 -1;
//overflow
uint256 overflowResult;
function getResults(uint256 a, uint256 b) public{
addResult = SafeMath.add(a,b);
subResult = SafeMath.sub(a,b);
mulResult = SafeMath.mul(a,b);
divResult = SafeMath.div(a,b);
modResult = SafeMath.mod(a,b);
overflowResult = SafeMath.add(SafeMath.add ( (a**b), SafeMath.mul (SafeMath.mul (b, a), b)), (b** b));
}
function addResultVal(uint a, uint b) public view returns(uint256){
return addResult;
}
function subResultVal() public view returns(uint256){
return subResult;
}
function mulResultVal() public view returns(uint256){
return mulResult;
}
function divResultVal() public view returns(uint256){
return divResult;
}
function modResultVal() public view returns(uint256){
return modResult;
}
function overflowResultVal() public view returns(uint256){
return overflowResult;
}
}
Go to the github page for any import you'll like to have for openzeppelin-contracts, "SafeMath" in this case, and copy the page url.
Ex:
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/math/SafeMath.sol";
Import the library right after pragma solidity. Then include it right after the opening of your contract.
pragma solidity ^x.x.x;
import "openzeppelin-solidity/contracts/utils/math/SafeMath.sol";
contract TheNameOfYourContract {
using SafeMath for uint;
.
.
...
}
creating a project from npx hardhat (2.8.3) selecting advanced project and then having a folder structure like this:
project
|--contracts
|--mycontract.sol
|--node_modules
|--{other files & folders}
The error is gone if I import libraries like this inside mycontract.sol:
pragma solidity ^0.8.4;
import "../node_modules/#openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/#openzeppelin/contracts/utils/math/SafeMath.sol";
import "../node_modules/#openzeppelin/contracts/access/Ownable.sol";
... other code
But this will not compile at least with hardhat. So it appears Solhint (.solhint.json) requires to know exactly the import paths but it ignores by default (.solhintignore) the node_modules folder. By removing node_modules from .solhintignore and restarting VS Code it works for me.
No longer needed but import that works for pragma solidity ^0.6.0;
would be:
import "#chainlink/contracts/src/v0.6/vendor/SafeMathChainlink.sol";