estimate_buy_price

Documentation for eth_defi.uniswap_v2.fees.estimate_buy_price function.

estimate_buy_price(uniswap, base_token, quote_token, quantity, *, fee=30, slippage=0, intermediate_token=None)[source]

Estimate how much we are going to need to pay when doing buy.

Calls the on-chain contract to get the current liquidity and estimates the the price based on it.

Example for Ethereum mainnet Uniswap:

import os

from web3 import Web3

from eth_defi.provider.multi_provider import create_multi_provider_web3
from eth_defi.uniswap_v2.deployment import fetch_deployment
from eth_defi.uniswap_v2.fees import estimate_buy_price
from eth_defi.uniswap_v2.pair import fetch_pair_details

# Default to Ankr free JSON-RPC endpoint if one not given
# https://eth.public-rpc.com/
web3 = create_multi_provider_web3(os.environ.get("JSON_RPC_ETHEREUM", "https://eth.public-rpc.com"))

assert web3.eth.chain_id == 1, f"We are not on Ethereum mainnet, got {web3.eth.chain_id}"

uniswap_v2 = fetch_deployment(
    web3=web3,
    factory_address="0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f",
    router_address="0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D",
    init_code_hash='0x96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f',
)

# Uniswap v2's USDC-WETH needs to be reserved to WETH-USDC in human logic
# https://tradingstrategy.ai/trading-view/ethereum/uniswap-v2/eth-usdc
pair = fetch_pair_details(web3, "0xb4e16d0168e52d35cacd2c6185b44281ec28c9dc", reverse_token_order=True)
print(f"Uniswap v2 pool is {pair.contract.address}, https://tradingstrategy.ai/trading-view/ethereum/uniswap-v2/eth-usdc")
print("Base token is", pair.get_base_token())
print("Quote token is", pair.get_quote_token())

raw_price = estimate_buy_price(
    uniswap_v2,
    base_token=pair.get_base_token().contract,
    quote_token=pair.get_quote_token().contract,
    quantity=1 * 10**18,  # 1 WETH = 1000000000000000000 wei
)

# Convert raw USDC Solidity amount -> human USDC
human_price = pair.get_quote_token().convert_to_decimals(raw_price)

print(f"Price is {human_price} ETH/USD")

Example for unit testing:

# Estimate how much ETH we will receive for 500 USDC.
# In this case the pool ETH price is $1700 so this should be below ~1/4 of ETH
amount_eth = estimate_buy_price(
    uniswap_v2,
    weth,
    usdc,
    1*10**18,
)
assert amount_eth / 1e18 == pytest.approx(0.28488156127668085)
Parameters
  • uniswap (eth_defi.uniswap_v2.deployment.UniswapV2Deployment) – Uniswap v2 deployment

  • base_token (web3.contract.contract.Contract) – Base token of the trading pair

  • quote_token (web3.contract.contract.Contract) – Quote token of the trading pair

  • quantity (int) – How much of the base token we want to buy

  • fee (int) – Trading fee express in bps, default = 30 bps (0.3%)

  • slippage (float) – Slippage express in bps

  • intermediate_token (Optional[web3.contract.contract.Contract]) –

Returns

Expected base token to receive

Return type

int