web3 python getAmountsOut 执行已恢复

Question

I managed to set up this function that returns the token value in USD of a contract, everything works fine in some contracts, but in other contracts I get the error " execution reverted " when calling the function " getAmountsOut " does anyone have any idea what it can be? I get the contracts from the same place in bscscan and for some it works and for some it doesn't.

bsc = 'https://bsc-dataseed.binance.org/'
web3 = Web3(Web3.HTTPProvider(bsc))
panRouterContractAddress = '0x10ED43C718714eb63d5aA57B78B54704E256024E'
panabi = '[{...}]'
contractbuy = web3.eth.contract(address=panRouterContractAddress, abi=panabi)  # PANCAKESWAP

def get_price(self):
    try:
        # Base currency token instantiate and ABI
        baseCurrency = web3.toChecksumAddress("0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56")  # BUSD

        # get symbol token
        sellTokenContract = web3.eth.contract(self.token_to_buy, abi=sellAbi)
        symbol = sellTokenContract.functions.symbol().call()

        # Selling token instance and contract
        tokenToSell = web3.toChecksumAddress(self.token_to_buy)  # TOKEN PRICE
        sellAmount = web3.toWei(1, 'ether')

        # Calculate minimum amount of tokens to receive
        amountOut = contractbuy.functions.getAmountsOut(sellAmount, [tokenToSell, baseCurrency]).call() # Error here

        amountOutMin = web3.fromWei(int(amountOut[1]), 'ether')
        print("Valor do token: ", str(amountOutMin))
        str_format = "{:." + self.decs_usd + "f}"
        return float(str_format.format(amountOutMin)), symbol

    except Exception as ex:
        print("ERRO:ver_preco:", ex)
        return "", ""

contracts ok:

https://bscscan.com/address/0x5649e392a1bac3e21672203589adf8f6c99f8db3

https://bscscan.com/address/0x00e1656e45f18ec6747f5a8496fd39b50b38396d

contracts error:

https://bscscan.com/address/0x9376e6b29b5422f38391a2a315623cb853c3c68e

https://bscscan.com/address/0xe786d5a4b985bfe5e371f8e94413cfb440f6618a

if anyone can explain to me why this error occurs in some tokens and not others, and how can i get error message details besides " execution reverted "

Thanks!

Answer 1

The latter specified token addresses fail with the error because there is no existing Pancakeswap pair contract for the specified address combination.

Another way of checking the existence of a pair contract is by calling the factory 's getPair() function.

// returns the existing pair contract address 0x5f7A2a0A32C0616898cA7957C1D58BC92a7E2f6f
getPair(
    // ZDC token specified in your question as OK
    "0x5649e392A1BAC3e21672203589aDF8f6C99f8dB3",

    // BUSD
    "0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56"
)

// returns the zero address 0x0000000000000000000000000000000000000000
// because there's no pair contract for these specified tokens
getPair(
    // DGZV token specified in your question as NOTOK
    "0x9376E6B29b5422f38391A2a315623cB853c3c68e",

    // BUSD
    "0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56"
)