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Get the Latest Price

This page explains how to get the latest price of Ethereum (ETH) inside smart contracts, using the ETH/USD Price Feed on the Kovan testnet.

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The full list of price feeds for each network are available from Price Feed Contracts.

Code Examples

Solidity

To consume price data, your smart contract should reference AggregatorV3Interface, which defines the external functions implemented by Price Feeds.

pragma solidity ^0.6.7;

import "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";

contract PriceConsumerV3 {

    AggregatorV3Interface internal priceFeed;

    /**
     * Network: Kovan
     * Aggregator: ETH/USD
     * Address: 0x9326BFA02ADD2366b30bacB125260Af641031331
     */
    constructor() public {
        priceFeed = AggregatorV3Interface(0x9326BFA02ADD2366b30bacB125260Af641031331);
    }

    /**
     * Returns the latest price
     */
    function getLatestPrice() public view returns (int) {
        (
            uint80 roundID, 
            int price,
            uint startedAt,
            uint timeStamp,
            uint80 answeredInRound
        ) = priceFeed.latestRoundData();
        // If the round is not complete yet, timestamp is 0
        require(timeStamp > 0, "Round not complete");
        return price;
    }
}

The latestRoundData function returns five values representing information about the latest price data. See API Reference for more details.

Javascript

const web3 = new Web3("https://kovan.infura.io/v3/<infura_project_id>");
const aggregatorV3InterfaceABI = [{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"description","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint80","name":"_roundId","type":"uint80"}],"name":"getRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"latestRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"version","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}];
const addr = "0x9326BFA02ADD2366b30bacB125260Af641031331";
const priceFeed = new web3.eth.Contract(aggregatorV3InterfaceABI, addr);
priceFeed.methods.latestRoundData().call()
    .then((roundData) => {
        // Do something with roundData
        console.log("Latest Round Data", roundData)
    });

Python

web3 = Web3(Web3.HTTPProvider('https://kovan.infura.io/v3/<infura_project_id>'))
abi = '[{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"description","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint80","name":"_roundId","type":"uint80"}],"name":"getRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"latestRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"version","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}]'
addr = '0x9326BFA02ADD2366b30bacB125260Af641031331'
contract = web3.eth.contract(address=addr, abi=abi)
latestData = contract.functions.latestRoundData().call()
print(latestData)

More Aggregator Functions

Getting the latest price is not the only data that can be retrieved from aggregators. You can also retrieve historical price data. To find out more, move on to Historical Price Data.

Updated about a month ago


What's Next

For more information on how Price Feeds obtain price data, read about Chainlink's Decentralised Data Model. Or, learn about how you can also obtain historical price data.

Decentralized Data Model
Historical Price Data

Get the Latest Price


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