uniswap low level swap call

2
votes

I can use the router02 function to swap tokens on uniswap:

route02.swapExactTokensForTokens(amtIn, amtOut,
         [t1.address, t2.address], addr, deadline(), {gasLimit: 4000000});

But how to call the low level swap function for uniswap directly? Here is my code but it didn't work. I have already send tokens to uni_v2_address before this function call.

const ethers = require('ethers');
const uni = new ethers.Contract(UNI_V2_ADDRESS, IUniswapV2Pair.abi, wallet);
let amt0out = BigInt(1) * BigInt(10**16);
let amt1out = BigInt(0);

//do swap
let tx = await uni.swap(amt0out, amt1out,
    addr, 0x0, {gasLimit: 4000000});
1
ethereumsolidity

1 Answers

0
votes

Remove the fourth parameter "data" like this:

let tx = await uni.swap(amt0out, amt1out, addr, {gasLimit: 4000000});

Passing anything in the fourth "data" parameter initiates a Flash Swap, optimistically transferring tokens to addr and attempting to call a function named "uniswapV2Call" on the addr as described here:

Uniswap Flash Swaps Documentation