How to get a quote and swap on 0x with ethers.js

Question

I'm trying to make a simple swap from 10 USDC to 10 USDT using 0x API quote.

I'm doing this:

import type { UnsignedTransaction } from '@ethersproject/transactions'
import { Web3Provider } from '@ethersproject/providers'

const provider = new Web3Provider(window.ethereum)

const [address] = await window.ethereum.request({ method: 'eth_accounts' })

const res = await fetch('https://api.0x.org/swap/v1/quote?buyAmount=1000000&buyToken=USDT&sellToken=USDC')

const quote = await res.json()

// not sure what to do next?

What should be the next step to perform a swap? Using a Web3Provider.

Reference: https://0x.org/docs/guides/swap-tokens-with-0x-api#selling-erc20-tokens

Answer 1

0x API returns a JSON object with standard ethereum transaction fields already populated. You should follow your web3 library's guide for sending transaction objects. Depending on whether you pass in takerAddress as part of your request, you may also have to populate the gas fied on your own.

Don't forget to set appropriate token allowances in advance.

Answer 2

Since the response of /quote endpoint is already a transaction, I think the line you have to add is :

const mintTx = await provider.sendTransaction(quote);

Answer 3

just seeing this, this setup worked for me, I pulled in the signer with the wagmi lib (useSigner hook):

await signer?.sendTransaction({
                        from: yourConnectedAddress,
                        to: quote.to,
                        data: quote.data,
                        value: quote.value,
                        gasLimit: quote.estimatedGas,
                    });