readOracle

The readOracle method is designed to retrieve the value from a specific oracle. This enables users to access data fetched by an oracle, which serves as a reliable source of information sourced from external APIs or other data providers.

Usage

As an example, we will utilize the CoinGecko public API oracle, which provides the Ethereum price in USD: CoinGecko Ethereum API.

const readOracleRes = await readerOrFactory.readOracle(
  'QmbXhtjAJysMMA69KkB8KohsEDTZA2PXuhYdAQcHjjQFit'
); // Content ID of the Oracle

TIP

You can utilize either type of SDK instance, be it the basic IExecOracleFactory or the IExecOracleReader, to invoke the readOracle method.

Parameters

import type { ReadOracleParams } from '@iexec/iexec-oracle-factory-wrapper';

paramSet or paramSetCid or oracleId

TIP

• The oracle ParamSet describes the parameters used to feed the oracle.

• Any different ParamSet has a unique ParamSetCid which is the Content ID of the document on IPFS. With a ParamSetCid anyone can retrieve the ParamSet from IPFS.

• The OracleId is the blockchain hash of the ParamSet it is used to store and read the value of an oracle on the Oracle contract.

• ParamSet of the Oracle to be read.

const paramSet: ParamSet = { 
  method: 'GET', 
  url: 'https://api.coingecko.com/api/v3/simple/price?ids=ethereum&vs_currencies=usd', 
  headers: { authorization: '%API_KEY%' }, 
  body: '', 
  dataset: '0x0eFf9Ba4304D5d3EB775cA9dB1F011e65C2eb0cE', 
  JSONPath: '$.ethereum.usd', 
  dataType: 'number', 
}; 

const readOracleRes = await readerOrFactory.readOracle(
  paramSet 
);

• ParamSet CID of the Oracle to be read.

const paramSetCid: ParamSetCID =
  'QmbXhtjAJysMMA69KkB8KohsEDTZA2PXuhYdAQcHjjQFit'; 

const readOracleRes = await readerOrFactory.readOracle(
  paramSetCid 
);

• Oracle ID of the Oracle to be read.

const oracleId: OracleID =
  '0xf0f370ad33d1e3e8e2d8df7197c40f62b5bc403553b103858359687491234491'; 

const readOracleRes = await readerOrFactory.readOracle(
  oracleId, 
  {
    dataType: 'number', // When reading an oracle from its OracleID, the dataType must be specified.
  }
);

options

dataType

When reading an oracle from its OracleID, the dataType must be specified.

const oracleId: OracleID =
  '0xf0f370ad33d1e3e8e2d8df7197c40f62b5bc403553b103858359687491234491';
const dataType: DataType = 'number';

const readOracleRes = await readerOrFactory.readOracle(
  oracleId,
  { 
    dataType, 
  } 
);

Return value

OracleValue

import type { OracleValue } from '@iexec/iexec-oracle-factory-wrapper';