// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.9.0 ;
interface AggregatorV3Interface {
function decimals() external view returns (uint8);
function description() external view returns (string memory);
function version() external view returns (uint256);
// getRoundData and latestRoundData should both raise "No data present"
// if they do not have data to report, instead of returning unset values
// which could be misinterpreted as actual reported values.
function getRoundData(uint80 _roundId)
external
view
returns (
uint80 roundId,
int256 answer,
uint256 startedAt,
uint256 updatedAt,
uint80 answeredInRound
);
function latestRoundData()
external
view
returns (
uint80 roundId,
int256 answer,
uint256 startedAt,
uint256 updatedAt,
uint80 answeredInRound
);
}
contract FundMe {
mapping (address => uint256) public addressTotalAmountFunded;
function fund() public payable {
addressTotalAmountFunded[msg.sender] += msg.value;
}
function getVersion() public view returns (uint256){
AggregatorV3Interface priceFeed = AggregatorV3Interface(0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419);
return priceFeed.version();
}
}
Hi I am trying to understand why I get this error when I want to check the version
Any thoughts?
The 0x5f4e... address hardcoded in your getVersion() function doesn't hold any smart contract on the Kovan testnet (link). Even though it has a contract deployed on the mainnet, these environments are separated.
When there's no smart contract on the address, there's nothing to send a response to the internal call. Your code expects an uint256 response from the version() call, so that it can return it from the getVersion().
When it doesn't receive the expected response, it throws an exception, effectively reverting the "main" call.
Make sure the address of the data feed is for the Testnet you are using (most likely Kovan) and not for Mainnet.
I experienced the same problem. The problem was with the network selection. You're requesting the price info from a wallet address/contract on Rinkby network. I tried the wallet address on the Kovan network instead and that worked for me.
This is the Kovan address I used 0x9326BFA02ADD2366b30bacB125260Af641031331
It worked find a returned the ETH/USD Price info.
So basically you can solve it in 2 ways:
Go to your metamask and change your network to Rinkby and use the rinkby ETH/USD address in your functions or
Keep your network on Kovan and use the Kovan ETH/USD address.
Related
I'm trying to make a normal request to another contract from mine.
function getUserAccountData(address _miskin) internal view returns (AaveUserData memory) {
ILendingPool lendingPool = ILendingPool(aaveLendingPoolAddress);
(uint256 totalCollateralETH, uint256 totalDebtETH, uint256 availableBorrowsETH, uint256 currentLiquidationThreshold, uint256 ltv, uint256 healthFactor) = lendingPool.getUserAccountData(_miskin);
return AaveUserData(totalCollateralETH, totalDebtETH, availableBorrowsETH, currentLiquidationThreshold, ltv, healthFactor);
}
This is pretty basic and on the line lendingPool.getUserAccountData(_miskin); I get an error: function returned an unexpected amount of data.
I don't understand why I have the correct contract address also.
This is my interface
interface ILendingPool {
function getUserAccountData(address user)
external
view
returns (
uint256 totalCollateralETH,
uint256 totalDebtETH,
uint256 availableBorrowsETH,
uint256 currentLiquidationThreshold,
uint256 ltv,
uint256 healthFactor
);
}
I someone have any idea what can I do I would love thank you.
A struct is decoded differently than the list of its arguments. In particular it has extra bytes at the beginning.
So your code is expecting a output like (uint256, ..., uint256) but getting a AaveUserData struct. I'm not sure how the output of your internal function getUserAccountData is used, but I guess you're reading it using the Aave ILendingPool interface, which doesn't return a AaveUserData struct.
It's a bit of a dum answer but I forked the wrong network so whe. I tried to call the address with the good polygon address I got an error. So the solution: Fork the good network.
Here are the steps I follow on Remix:
Deploy my ERC20Basic token and my DEX contract.
DEX.buy > Buy ERC20Basic tokens in exchange of ETH (works fine).
ERC20Basic.approve(contractAddress, tokenAmount) (works fine).
ERC20Basic.allowance > Works fine, function returns the amount of the allowance.
The problem comes when I try to sell tokens with this function from my DEX contract:
function sell(uint256 amount) public {
uint256 allowance = token.allowance(msg.sender, address(this));
require(allowance >= amount, "Check the token allowance");
token.transferFrom(msg.sender, address(this), amount);
payable(msg.sender).transfer(amount);
emit Sold(amount);
}
I still get "Check the token allowance".
When I log the allowance I get 0.
When I log msg.sender and address(this), I get the same addresses I used on the Remix interface to get the value of the allowance manually.
It feels like the allowance is reset to 0 when I call the sell function or that the sell function can't reach the value of the allowance. Maybe this is something about memory and storage?
My allowance function inside of ERC20Basic contract is:
function allowance(address owner, address delegate)
public
view
override
returns (uint256)
{
return allowed[owner][delegate];
}
Approval function:
function approve(address delegate, uint256 numTokens)
public
override
returns (bool)
{
allowed[msg.sender][delegate] = numTokens;
emit Approval(msg.sender, delegate, numTokens);
return true;
}
Allowance structure:
mapping(address => mapping(address => uint256)) allowed;
How are you calling the approve function?
In your code you aren't passing the require statement because your approval wasn't successful. If it was your allowance wouldn't be 0.
You are probably calling the approve function from the contract which won't work because then the msg.sender would be address of the contract not your accounts address.
You have to approve the amount manually outside of the contract for it to work.
I am very new to Solidity, and have recently been working on trying to learn the ropes. For reference, I have been using code from this video (https://www.youtube.com/watch?v=tBMk1iZa85Y) as a primer after having gone through the basic crypto zombies tutorial series.
I have been attempting to adapt the Solidity contract code presented in this video (which I had functioning just fine!) to require a Burn of a specified amount of an ERC-20 token before minting an NFT as an exercise for myself. I thought I had what should be a valid implementation which compiled in Remix, and then deployed to Rinkeby. I call the allowAccess function in Remix after deploying to Rinkeby, and that succeeds. But, when I call the mint function with the two parameters, I get: "gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending? execution reverted."
If I still send the transaction, metamask yields "Transaction xx failed! Transaction encountered an error.".
I'm positive it has to do with "require(paymentToken.transfer(burnwallet, amounttopay),"transfer Failed");", though I'm not sure what's wrong. Below is my entire contract code. I'm currently just interacting with the Chainlink contract on Rinkeby as my example, since they have a convenient token faucet.
pragma solidity ^0.8.0;
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/IERC20.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/access/Ownable.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Counters.sol";
contract myNFTwithBurn is ERC721, Ownable {
address externalTokenAddress = 0x01BE23585060835E02B77ef475b0Cc51aA1e0709; //Token Type to burn on minting
uint256 amounttopay = 5; //number of these tokens to burn
IERC20 paymentToken = IERC20(externalTokenAddress); //my code: create an interface of the external token
address burnwallet = 0x000000000000000000000000000000000000dEaD; //burn wallet
using Counters for Counters.Counter;
Counters.Counter private _tokenIds;
using Strings for uint256;
// Optional mapping for token URIs
mapping (uint256 => string) private _tokenURIs;
// Base URI
string private _baseURIextended;
constructor() ERC721("NFTsWithBurn","NWB") {
}
function setBaseURI(string memory baseURI_) external onlyOwner() {
_baseURIextended = baseURI_;
}
function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
_tokenURIs[tokenId] = _tokenURI;
}
function _baseURI() internal view virtual override returns (string memory) {
return _baseURIextended;
}
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory _tokenURI = _tokenURIs[tokenId];
string memory base = _baseURI();
// If there is no base URI, return the token URI.
if (bytes(base).length == 0) {
return _tokenURI;
}
// If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
if (bytes(_tokenURI).length > 0) {
return string(abi.encodePacked(base, _tokenURI));
}
// If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.
return string(abi.encodePacked(base, tokenId.toString()));
}
function allowAccess() public
{
paymentToken.approve(address(this), 5000000); //This is my attempt to allow the contract access to the user's external tokens, in this case Chainlink (paymentToken)
}
function mintItem(address to, string memory tokenURI)
public
onlyOwner
returns (uint256)
{
require(paymentToken.transfer(burnwallet, amounttopay),"transfer Failed"); //Try to transfer 5 chainlink to the burn wallet
_tokenIds.increment();
uint256 id = _tokenIds.current();
_mint(to, id);
_setTokenURI(id, tokenURI);
return id;
}
}
If anybody can at least point me to what I'm doing completely wrong in the code that I've added, please do! TIA!
I'm not sure why are you trying to burn link in order to mint and nft but first check if the link code does not have a require that check if the destination address is the burn address if it has then burn the link is not possible and you should use any other erc20 maybe your own erc20, also your contract probably does not have any link and if you want to transfer the link from the user you should do this in the contract paymentToken.transferFrom(msg.sender,destinationAddress,amount) and if the user previously approve your contract you will able to send the tokens, and i suppose that the purpose of the allowAccess function is to make the user approve the contract to move the tokens that will never work, the approve function let's anyone that call it approve any address to move an amount of tokens, the thing is that to know who is approving to let other to move the tokens the function use msg.sender to explain how this work take a look at this example
let's say that your contract is the contract A and the link contract is the contract B
now a user call allowAccess in the contract A, so here the msg.sender is the user because they call the function
now internally this function call approve on contract B, here the contract A is the msg.sender, because the contract is who call the function
so what allowAccess is really doing is making the contract approving itself to move their own tokens that I assume it doesn't have
I'm really really inexperienced with contracts and need your help. I created a contract with remix and sent some bnb to it. I want to retrieve it but I can't seem to make it happen.
pragma solidity ^0.8;
interface IERC20 {
function transfer(address _to, uint256 _amount) external returns (bool);
}
contract MyContract {
function withdrawToken(address _tokenContract, uint256 _amount) external {
IERC20 tokenContract = IERC20(_tokenContract);
// transfer the token from address of this contract
// to address of the user (executing the withdrawToken() function)
tokenContract.transfer(msg.sender, _amount);
}
}
This is the code that I'm using from another post but I don't understand it. Do I have to change the "_to" "and "_amount" with the numbers or do I just copy the code and compile it?
I'm really sorry but I have no idea what I did so I just want to take the tokens back.
Thanks
Sorry but you can't withdraw your bnb, bnb isn't a token, bnb is like the ether in ethereum, the native chain currency and the contract doesn't have a function to let you withdraw it, the only way is if you send wbnb, in that case you can look the address of the contract of the wbnb and call the function withdraw of the contract you made
As Jhonny said, BNB is not an actual token, and so your implemented logic won't work to withdraw BNB. But just for you to know, you could create a function which only allows withdrawing BNB (which is the native currency). It would be something like this:
function withdraw(uint _amount) external {
payable(msg.sender).transfer(_amount);
}
Hope you find this useful.
I try to transfer Ether from the contract to an address but it gives the error that the transaction is out of gas. I think it's a small problem but I can't find it. I have to specifically use solidity version 0.4.24.
The warning from Remix
The error from MetaMask
I have tried different methods, like:
address.transfer(amount);
address.send(amount);
address.call.value(amount)( );
All methods will give the same out of gas exception. and the send and call method will also give a warning that it's outdated and that I should use the transfer method.
I also tried to adjust the gas and it didn't work, I also tried the needed 2,300 for the transfer listed on the docs.
The code:
pragma solidity ^0.4.24;
contract TestContract {
function payAddress(address _address) external payable {
_address.transfer(msg.value);
}
}
If the problem is that the contract doesn't have any Ether to transfer, can it use the Ether I send with the function call? Or is the problem something else?
Thank you for reading.
edit:
I have tried to send Ether to my Contract and that works, I do have Ether on my contract now, but the function still gives the same error as before. So the problem is something else.
Current code:
pragma solidity ^0.4.24;
contract TestContract {
function() external payable { }
function payContract() public payable {}
function paySomeone(address _address, uint256 _amount) external {
_address.transfer(_amount);
}
function getBalance() public view returns (uint256) {
return address(this).balance;
}
}
The balance of the contract
The parameters I use
Same MetaMask error as before
As you can see here the balance of the contract is 10 wei, but when i try to send 9 wei it still gives the same out of gas error. I also still get the same error from Remix as before.
I also post the issue on the Stack exchange and got an answer there. The issue was my
Ganache version. I switched to the Robsten test network and it worked. I'll link the post here.
Yes. In order to send ether from contract to another address, first you must send some ether to the contract address. Take a look at this and this.