incredible swap

[speriamoBene]

Hello, i did a swap a little while ago and inexplicably lost 13,900 usdt

i just used the instruction

uniswap.make_trade(usdt, symbolUniswap, 13900 * 1000000)

where:
usdt = Web3.toChecksumAddress("0xdac17f958d2ee523a2206206994597c13d831ec7")
symbolUniswap = Web3.toChecksumAddress("0x7d29a64504629172a429e64183d6673b9dacbfce")

But i only received the equialent of 17 usdt instead of 13,9k.
How is it possible?

[ErikBjare]

Impossible to say without looking at the tx.

Edit: Also, your address for the UNI token is not correct. Seems to be for something else called VXV: https://etherscan.io/token/0x7d29a64504629172a429e64183d6673b9dacbfce

Edit 2: Looks like you may have tried to swap using Uniswap v2, which has almost no liquidity for the VXV token: https://v2.info.uniswap.org/pair/0x0c9c5daf1d7cd8b10e9fc5e7a10762f0a8d1c335

TX should have failed though due to excessive slippage (unless you've set that to something high, or there's a bug). If price impact is expected, it wouldn't fail the slippage check.

Edit 3: Found the tx https://etherscan.io/tx/0xb6e8e667ed8489ae071c4327b24bdec1193e9e76ba767421e72370ece1859420/

Indeed, the estimated price was exactly what you got.

Sorry this happened to you. You need to be careful to use a pool that has liquidity (and always check the estimated price before executing!). Thinking of ways to make this clearer in the docs.

[speriamoBene]

Thanks for the reply. In fact, when analyzing the transaction, I used a cashless pool.
Is there a way to check that there is liquidity before executing the trade?
Also, I used Uniswap V2 in this way:

uniswap = Uniswap (address = address, private_key = private_key, version = 2, provider = provider)

If I enter version = 3, is Uniswap V3 supported or do I need to update something?

Thank you very much

[ErikBjare]

Answered by @liquid-8 below. Working on improving docs and adding a estimate_price_impact helper function.

[liquid-8]

You can define a method that returns the pool's contract for the given pair of tokens. Code snippet:

def get_pair_contract(self, token0: AddressLike, token1: AddressLike, fee: int) -> AddressLike:
    if self.version == 2:
        params = [web3.toChecksumAddress(token0), web3.toChecksumAddress(token1)]
        pair_token = self.factory_contract.functions.getPair(*params).call()
    elif self.version == 3:
        params = [web3.toChecksumAddress(token0), web3.toChecksumAddress(token1), fee]
        pair_token = self.factory_contract.functions.getPool(*params).call()
    else:
        pair_token = None
    return pair_token

Then just analyze this contract in the way you like: programmatically or via third-part tools like Etherscan.

If I enter version = 3, is Uniswap V3 supported or do I need to update something?

If you use the latest version then yes, that's all you need to do, basically.

Addition: you need direct pool @ uniV3 for your pair of tokens to trade as current version doesn't support multihop swaps. Also, you have to set proper value for V3 fee.

[speriamoBene]

Thank you very much

[speriamoBene]

Sorry again, but i got this error:

object has no attribute 'factory_contract'

how can i solve it please?

[speriamoBene]

Nope. Is there a way to get money back?

[FILAgiao]

I don't know. I contacted with them on twitter. Have no reply yet...

[speriamoBene]

who did you contact?

[ErikBjare]

I answered @FILAgiao in #208 (comment)

[FILAgiao]

who did you contact?

Just DM uniswap.

[FILAgiao]

The same problem comes to me...lost almost 1.5k$,i do should read that instruction carefully...