Band standard dataset

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Developers building on Polygon can now leverage Band Protocol’s decentralized oracle infrastructure. With Band Protocol’s oracle, they now have access to various cryptocurrency price data to integrate into their applications.

Supported tokens¶

Currently, the list of supported symbols can be found at https://data.bandprotocol.com/. Going forward, this list will continue to expand based on developer needs and community feedback.

Price pairs¶

The following methods can work with any combination of base/quote token pair, as long as the base and quote symbols are supported by the dataset.

Querying prices¶

Currently, there are two methods for developers to query prices from Band Protocol’s oracle: through Band’s StdReference smart contract on Polygon and through their bandchain.js JavaScript helper library.

Solidity smart contract¶

To query prices from Band Protocol’s oracle, a smart contract should reference Band’s StdReference contract, specifically the getReferenceData and getReferenceDatabulk methods.

getReferenceData takes two strings as the inputs, the base and quote symbol, respectively. It then queries the StdReference contract for the latest rates for those two tokens, and returns a ReferenceData struct, shown below.

struct ReferenceData {
    uint256 rate; // base/quote exchange rate, multiplied by 1e18.
    uint256 lastUpdatedBase; // UNIX epoch of the last time when base price gets updated.
    uint256 lastUpdatedQuote; // UNIX epoch of the last time when quote price gets updated.
}

getReferenceDataBulk instead takes two lists, one of the base tokens, and one of the quotes. It then proceeds to similarly query the price for each base/quote pair at each index, and returns an array of ReferenceData structs.

For example, if we call getReferenceDataBulk with ['BTC','BTC','ETH'] and ['USD','ETH','BNB'], the returned ReferenceData array will contain information regarding the pairs:

BTC/USD
BTC/ETH
ETH/BNB

Contract addresses¶

Blockchain	Contract Address
Polygon (Test)	`0x56e2898e0ceff0d1222827759b56b28ad812f92f`

BandChain.JS¶

Band’s node helper library bandchain.js also supports a similar getReferenceData function. This function takes one argument, a list of token pairs to query the result. It then returns a list of corresponding rate values.

Example usage¶

The code below shows an example usage of the function:

const { Client } = require('@bandprotocol/bandchain.js');

// BandChain's REST Endpoint
const endpoint = 'https://rpc.bandchain.org';
const client = new Client(endpoint);

// This example demonstrates how to query price data from
// Band's standard dataset
async function exampleGetReferenceData() {
  const rate = await client.getReferenceData(['BTC/ETH','BAND/EUR']);
  return rate;
}

(async () => {
  console.log(await exampleGetReferenceData());
})();

The corresponding result will then be similar to:

$ node index.js
[
    {
        pair: 'BTC/ETH',
        rate: 30.998744363906173,
        updatedAt: { base: 1615866954, quote: 1615866954 },
        requestID: { base: 2206590, quote: 2206590 }
    },
    {
        pair: 'BAND/EUR',
        rate: 10.566138918332376,
        updatedAt: { base: 1615866845, quote: 1615866911 },
        requestID: { base: 2206539, quote: 2206572 }
    }
]

For each pair, the following information will be returned:

pair: The base/quote symbol pair string.
rate: The resulting rate of the given pair.
updated: The timestamp at which the base and quote symbols was last updated on BandChain. For USD, this will be the current timestamp.
rawRate: This object consists of two parts.
value is the BigInt value of the actual rate, multiplied by 10^decimals.
decimals is then the exponent by which rate was multiplied by to get rawRate.

Example usage¶

This contract demonstrates an example of using Band’s StdReference contract and the getReferenceData function.