This one looks like it will be a bit more challenging since there is no HTTP API avail

Thanks <a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-u

resolved by <a class="issue-link js-issue-link" data-error-text="Failed to load title"

Add support for Uniswap about ethereum-dex-prices-service HOT 3 CLOSED

perich commented on August 22, 2024 3

Add support for Uniswap

from ethereum-dex-prices-service.

Comments (3)

haydenadams commented on August 22, 2024 1

If you guys are open to using web3 directly, prices are very easy. There is a mapping of tokenAddress -> exchangeAddress which you can get from the now finished directory API endpoint, or can just pull all NewExchange events. Or just call getExchange(tokenAddress) on the factory.

If I want to calculate the cost of buying/selling DAI, all you need is the ETH and DAI balance of the DAI exchange contract:

ethReserve = web3.eth.getBalance(daiExchangeAddress)
erc20Reserve = daiContract.balanceOf(daiExchangeAddress)

then you just plug into either the buy or sell formula, as implemented in the contract:

/*
If you're selling ERC20 for ETH, sold reserve is erc20Reserve, boughtReserve is ethReserve
If you're selling ETH for ERC20, sold reserve is ethReserve, boughtReserve is erc20Reserve
*/
function sellPrice(amountSold, soldReserve, boughtReserve) {
   numerator = amountSold * boughtReserve * 997
   denominator = soldReserve * 1000 + amountSold * 997
   amountBought = numerator / denominator
}

/*
If you're buying ERC20 with ETH, sold reserve is ethReserve, boughtReserve is erc20Reserve
If you're buying ETH with ERC20, sold reserve is erc20Reserve, boughtReserve is ethReserve
*/
function buyPrice(amountBought, soldReserve, boughtReserve) {
   numerator = amountBought * soldReserve * 1000
   denominator = (boughtReserve - amountBought) * 997
   amountSold = numerator / denominator + 1
}