identify if a contract is v2 or v3 (uniswap)

[ubuntutest]

Describe the Feature

it would be interesting to somehow understand if a contract you are about to interact with is a v2 or v3 contract as the router_address is different, if there is no way it would be interesting to implement one.

Code Example

No response

[ricmoo]

This isn’t really under the purview of ethers; this would be up to a higher level library offering a Uniswap API. :)

[ubuntutest]

Thanks for moving the topic to the right category.

Interactions with v2 and v3 tokens by a user on a Dapp need a different router_address.

I wonder how the dapps manage this case, if in case of error they use the opposite router or there is a mode that escapes me.

[ricmoo]

I don’t know the uniswap API, you would likely run a method against both to find the best option and present it (optionally with an option to fallback onto the other) and just keep two contract objects around and just use the “right” one (where right is either the best option, what the user picked through the UI, etc). It just depends on why/when you would use one vs. the other as two which contract object you would create and/or use. If I understand the problem, which maybe I’m missing. :)

[ubuntutest]

After this answer I created two different functions with the getAmountsOut method that call router_address v2 and v3, they gave me values in line with those of uniswap, it worked perfectly in fact I implemented it in my dapp in production.

Since this morning it doesn't work anymore, I have tried in every way. The getAmountsOut () method with the v3 version does not seem valid, yet a few hours ago it worked, now I get this error:

  reason: 'missing revert data in call exception; Transaction reverted without a reason string',
  code: 'CALL_EXCEPTION',
  data: '0x',
  transaction: {
    from: '0x5C5...',
    to: '0xE592427A0AEce92De3Edee1F18E0157C05861564',
    data: '0xd06ca61f000000000000.............3e130629c2b854b7ba9195',
    accessList: null
  },

  error: Error: execution reverted

I don't think it's a uniswap API problem as I only use ethers.js and this specific function in the router:

        router = new ethers.Contract(
            ROUTER_ADDRESS,
            [
                `function getAmountsOut(uint amountIn, address[] memory path) public view returns (uint[] memory amounts)`,
            ],
            account
        );

I don't have any uniswap sdk import or anything related.

[ubuntutest]

A simple advice but, theoretically, effective. Thank you!
If I don't go too far off the topic, I take this opportunity to ask you another question.
I am testing my Dapp on goerli, I use ZETA and DAI token, I am looking for a V3 only and V2 only token for the problem mentioned in the topic.
Do you have any token suggestions that I can use liquidity for swaps?

[ricmoo]

No idea, sorry. Other than occasionally using Uniswap, I’ve never done any testing or used their service in an automated fashion…