Pricefeed in a Upkeep

[obc92]

Is it posible to integrate a price feed that checks Ethereum price inside a checkUpkeep function?

[krakxn]

It is definitely possible, but why? That is not appropriate for checkUpkeep.

To keep things modular--and also for reusability--just create a separate contract, or a function inside the main contract. This way you can invoke it inside your checkUpkeep if there is some conditional necessary for checkUpkeep's context--elsewise no; do not include it if it is not appropriate contextually inside checkUpkeep.

[othaime-en]

^ checkUpkeep() seems peculiar to add this kind of functionality. Maybe create a separate function and implement the functionality in fulfillRandomWords(). fullRandomWords() seems appropriate.

[obc92]

The code is about implementing a contract were keepers chack eth price and when the price is lower than an stop loss placed before in the contract the keepers execute a sell order on uniswap V3. So inside checkUpkeep() function I want a call on another function that calls the price feed. This is the code, seems logic for me.

//priceFeed
    function getPrice() internal returns(uint256) { //Function where I call the conversion
       
        uint256 EthPrice = TokenPrice.dolarValue(priceFeed);
        return EthPrice;
    }

    //Keepers
    function checkUpkeep(bytes memory /* checkData */) public view override returns (
        bool upkeepNeeded, 
        bytes memory num,
        bytes memory value
        ){
        
        bool sellTime; 
        bool Quant;
        uint256 EthPrice;

        EthPrice = getPrice();

        address[] memory id = new address[](s_Wallets.length);

        for (uint i = 0; i < s_Wallets.length; i++) {           //Search in loop which Stop should be triggered
          id[i] = s_Wallets[i];
          Dades memory Data = s_Registre[id[i]];
          uint256 SL = Data.Stop;
          uint256 Q = Data.Quantity;
          sellTime = (SL <= EthPrice); 
          Quant = (Q > 0);
          if (sellTime && Quant){
            num = abi.encodepacked(i);
            value = abi.encodepacked(Q);
          }
          upkeepNeeded = (sellTime && Quant); //All conditions must be True
        }  
        return (upkeepNeeded, num, value);
    }

    function performUpkeep(bytes calldata num, bytes calldata value) external override {
        (bool upkeepNeeded, ) = checkUpkeep("");
        // require(upkeepNeeded, "Upkeep not needed");
        if (!upkeepNeeded) {
            revert Order__UpkeepNotNeeded(
                address(this).balance,
                s_Wallets.length
            );
        }
        //Byte conversion to uint
        uint256 number;
        for(uint i=0;i<num.length;i++){
            number = number + uint(uint8(num[i]))*(2**(8*(num.length-(i+1))));
        }
        uint256 Val;
        for(uint i=0;i<value.length;i++){
            Val = Val + uint(uint8(value[i]))*(2**(8*(value.length-(i+1))));
        }
        
        //Sell Val in UniswapV3
        // ··············
        // ··············

        // Reset data from wallet number
        // Reseteja les dades
        Dades storage dades = s_Registre[s_Wallets[number]];
        dades.Quantity = 0;
        dades.Stop = 0;
        //Delets wallet from the list
        s_Wallets = Remove(num);
        
    }

Wallet number and quantity are send to the performUpkeep() function to execute the sell on the Dex and delete wallet registered data on the contract. I have used this function before and don't understand the errors are throwing me now:

TypeError: Overriding function return types differ.
   --> contracts/MarketOrder.sol:113:5:
    |
113 |     function checkUpkeep(bytes memory /* checkData */) public view override returns (
    |     ^ (Relevant source part starts here and spans across multiple lines).
Note: Overridden function is here:
  --> @chainlink/contracts/src/v0.8/interfaces/KeeperCompatibleInterface.sol:22:3:
   |
22 |   function checkUpkeep(bytes calldata checkData) external returns (bool upkeepNeeded, bytes memory performData);
   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


TypeError: Function has override specified but does not override anything.
   --> contracts/MarketOrder.sol:143:79:
    |
143 |     function performUpkeep(bytes calldata num, bytes calldata value) external override {
    |                                                                               ^^^^^^^^


TypeError: Contract "MarketOrder" should be marked as abstract.
  --> contracts/MarketOrder.sol:12:1:
   |
12 | contract MarketOrder is KeeperCompatibleInterface {
   | ^ (Relevant source part starts here and spans across multiple lines).
Note: Missing implementation: 
  --> @chainlink/contracts/src/v0.8/interfaces/KeeperCompatibleInterface.sol:40:3:
   |
40 |   function performUpkeep(bytes calldata performData) external;
   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


TypeError: Member "encodepacked" not found or not visible after argument-dependent lookup in abi.
   --> contracts/MarketOrder.sol:135:19:
    |
135 |             num = abi.encodepacked(i);
    |                   ^^^^^^^^^^^^^^^^


Error HH600: Compilation failed

Do you have any advice?

[krakxn]

Well, as stated above, why not just create a different contract, or a different function in the same contract to do the logic involved in checkUpkeep instead of "forcing" it into that context. Also, if you ever want to then use that specific function somewhere else, you will have to check for everything which is redundant and a waste of time.

About the errors:

TypeError: Contract "MarketOrder" should be marked as abstract. occurs when you inherit a contract but do not use its properties; therefore being a redundant inheritance usage and should not be inherited.

TypeError: Function has override specified but does not override anything. Make sure it overrides some attribute in the file you are importing, if not, override is unnecessary and should be removed.

TypeError: Overriding function return types differ. This one is straightforward.

TypeError: Member "encodepacked" not found or not visible after argument-dependent lookup in abi. I do not see ABI anywhere in the code snippet provided; even if it is there, make sure the scope is appropriate by declaring it globally (scope).

[obc92]

Is this not what I have done, I mean if I'm understanding what you are saying:
Here is the other contract which calls the eth pricefeed.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.8;

import "@chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol"; // PriceFeed contract imported from chainlink github

library TokenPrice {
    /**
     * Network: Rinkeby
     * Aggregator: ETH/USD
     * Address: 0x8A753747A1Fa494EC906cE90E9f37563A8AF630e
     */
    function getLatestPrice(AggregatorV3Interface priceFeed) internal view returns (uint256) {
        (
            /*uint80 roundID*/,
            int256 price,
            /*uint startedAt*/,
            /*uint timeStamp*/,
            /*uint80 answeredInRound*/
        ) = priceFeed.latestRoundData();
        return uint256(price);// Retorna 8 decimals
    }

    function dolarValue(AggregatorV3Interface priceFeed) internal view returns(uint256) {
        uint256 Price = getLatestPrice(priceFeed);
        uint256 EthAmount = Price/100000000;
        return EthAmount;
    }
}

Which is called by the function:

function getPrice() internal returns(uint256) { //Function where I call the conversion
       
        uint256 EthPrice = TokenPrice.dolarValue(priceFeed);
        return EthPrice;
    }

and inside the checkUpkeep() as EthPrice = getPrice(); to get the dolar price inside the checkUpkeep().

Also why saying I'm not calling inheritance if I'm using both keepers functions?

Solved encodePacking error, thanks!

[alymurtazamemon]

@obc92 Yes, checkUpkeep basically contains the logic that when gets true Chainlink nodes should perform their functions. So you can add anything inside it for the condition statement. You way is correct you can get the price feed from a separate function and call it inside the checkUpkeep for condition.

[obc92]

Thank you guys. Actually the main problem looks like it was about sending multiple parameters to the performUpkeep(bytes calldata num, bytes calldata value) instead of encode multimple data in the Bytes memory parameter.