Get onchain price of Uniswap v3 pool (#138)

* Add util func to get onchain price of uni v3 pool

* Add test and changelog

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.21.9
+
+- Add utility function `get_onchain_price()` to ask on-chain price of a 
+ Uniswap v3 pool at any given block number
+
 # 0.21.8
 
 - Add test coverage for `extract_timestamps_json_rpc_lazy`

eth_defi/uniswap_v3/pool.py

@@ -1,10 +1,11 @@
 """Uniswap v3 pool data."""
-from decimal import Decimal
 from dataclasses import dataclass
+from decimal import Decimal
 from typing import Union
 
 from eth_typing import HexAddress
 from web3 import Web3
+from web3.contract import Contract
 
 from eth_defi.abi import get_deployed_contract
 from eth_defi.token import TokenDetails, fetch_erc20_details
@@ -33,6 +34,9 @@ class PoolDetails:
  #: Pool fee as % multiplier, 1 = 100%
  fee: float
 
+ #: Pool contract proxy
+ pool: Contract
+
  def __repr__(self):
  return f"Pool {self.address} is {self.token0.symbol}-{self.token1.symbol}, with the fee {self.fee * 100:.04f}%"
 
@@ -72,6 +76,7 @@ def fetch_pool_details(web3, pool_contact_address: Union[str, HexAddress]) -> Po
  token1,
  raw_fee,
  raw_fee / 1_000_000,
+ pool,
  )
 
 

eth_defi/uniswap_v3/price.py

@@ -3,8 +3,10 @@
 from decimal import Decimal
 
 from eth_typing import HexAddress
+from web3 import Web3
 
 from eth_defi.uniswap_v3.deployment import UniswapV3Deployment
+from eth_defi.uniswap_v3.pool import fetch_pool_details
 from eth_defi.uniswap_v3.utils import encode_path
 
 
@@ -216,3 +218,24 @@ def estimate_sell_received_amount(
  return amount, current_block
 
  return amount
+
+
+def get_onchain_price(
+ web3: Web3,
+ pool_contract_address: str,
+ *,
+ block_identifier: int | None = None,
+ reverse_token_order: bool = False,
+):
+ """Get the current price of a Uniswap pool.
+
+ :param web3: Web3 instance
+ :param pool_contract_address: Contract address of the pool
+ :param block_identifier: A specific block to query price
+ :param reverse_token_order: If set, assume quote token is token0
+ :return: Current price
+ """
+ pool_details = fetch_pool_details(web3, pool_contract_address)
+ _, tick, *_ = pool_details.pool.functions.slot0().call(block_identifier=block_identifier)
+
+ return pool_details.convert_price_to_human(tick, reverse_token_order)

tests/uniswap_v3/test_uniswap_v3_price.py

@@ -20,6 +20,7 @@
  UniswapV3PriceHelper,
  estimate_buy_received_amount,
  estimate_sell_received_amount,
+ get_onchain_price,
 )
 from eth_defi.uniswap_v3.utils import get_default_tick_range
 
@@ -313,3 +314,21 @@ def test_estimate_sell_received_cash(
  )
  assert usdc_received / 1e18 == pytest.approx(14159.565580618213)
  assert block_number > 0
+
+
+def test_get_onchain_price(web3, weth_usdc_uniswap_pool: str):
+ """Test get onchain price of a pool."""
+
+ price = get_onchain_price(
+ web3,
+ weth_usdc_uniswap_pool,
+ )
+
+ assert price == pytest.approx(Decimal(1699.9057541866793))
+
+ reverse_price = get_onchain_price(
+ web3,
+ weth_usdc_uniswap_pool,
+ reverse_token_order=True,
+ )
+ assert reverse_price == pytest.approx(Decimal(0.00058826790693372))