getPair call via Ethers.Contract does not return a pair address

[Samboy76]

Hi,

When I call following getPair under uniswapFactory contract I created via ethers.Contract in my javascript it doesn´t return any pair address.

const UniswapV2Factory = require("./build/contracts/IUniswapV2Factory.json");

uniswapFactory = new ethers.Contract(
		'0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f', // uniswap v2 factory address in Etherscan mainnet
		UniswapV2Factory.abi, wallet
	);

	const pairAddress = await uniswapFactory.getPair(wethAddress, otherAddress);
  	const pair = new Contract(pairAddress, UniswapV2Pair.abi, wallet);
	console.log("yeah2!");

Strange thing is if I removed await keywork it returns Promise { }.

However, if I run await uniswapFactory.getPair(wethAddress, otherAddress); directly under Truffle console it resolves the pair address correctly.

Any suggestions would be greatly appreciated as it´s been bugging me also for a very long time.

Thank you

[apdan510]

Hey @Samboy76 How do you run your JS script? You mentioned getPair working okay inside Truffle console? Any more screenshots, logs, or info you can share?

Thank you!
-Alex

[Samboy76]

Have raised Truffle Ticket #945282. Also shared the repo pointing to priceBotChecker.js which is the issue.
Much appreciate your help!

[apdan510]

Saw the ticket. Thank you! Ill get more eyes on this issue while I am sifting through the code. Thank you!

[Samboy76]

Thanks a lot @apdan510.
Looking fwd to your finds...

[Samboy76]

https://github.com/Samboy76/Flashloan-arbitrage

[Samboy76]

priceBotChecker.js

[apdan510]

Got the repo. Thank you! Will hop on analysis with the rest of team tomorrow morning. Hoping its a small bug somewhere.

…

On Thu, Sep 29, 2022, 2:20 PM Samboy76 ***@***.***> wrote: priceBotChecker.js — Reply to this email directly, view it on GitHub <#5566 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJSDIQQAM4ZQ3CR2PUHD7MTWAYB2PANCNFSM6AAAAAAQWEYO4U> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[apdan510]

• This is a suspected bug that happens in a Truffle project when working with Uniswap pair addresses. There are no errors when this project is converted to a HH project *

[Samboy76]

It goes well beyond in that the issue lies in its inability to make any on-chain call outs to the network not just limited to Uniswap pair addresses. This was the case for me because I couldn´t even retrieve the pair´s reserves through getReserves() even when I attempted to retrieve the pairAddress off-chain like through CREATE2 beforehand as shown on the docs.