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EVM integration

Integrate Pragma to your contract​

Overview​

The Pragma oracle contract provides various data feeds including spot median prices, TWAPs, realized volatility, options data, and perpetuals data. This guide will help you integrate these data feeds into your smart contracts.

Prerequisites​

  • Solidity ^0.8.0
  • The address of the deployed Pragma oracle contract (you can find the list of deployed contracts here)

Integration steps​

Integration through Pragma Solidity SDK​

The easiest way to fetch prices from Pragma contracts is through the Pragma Solidity SDK, by interacting with the Pragma.sol interface. You can also check out the full Solidity API documentation for the Solidity SDK.

Here is the installation steps for forge and hardhat/truffle.

# Install Foundry (Forge)
curl -L https://foundry.paradigm.xyz | bash
foundryup

# Install the Solidity SDK for Forge
forge install @pragmaoracle/solidity-sdk

Once installed, you can use this code snippet for your integration: 

pragma solidity ^0.8.0;
 
import "@pragmaoracle/solidity-sdk/IPragma.sol";
import "@pragmaoracle/solidity-sdk/PragmaStructs.sol";
 
contract YourContract {
  IPragma oracle;
 
  /**
   * @param pragmaContract The address of the Pragma contract
   */
  constructor(address pragmaContract) {
    // The IPragam interface from the sdk provides the methods to interact with the Pragma contract.
    oracle = IPragma(pragmaContract);
  }
 
  /**
     * This method is an example of how to interact with the Pragma contract to fetch Spot Median updates. You can check the documentation to 
     * find the available feeds.
     * @param priceUpdate The encoded data to update the contract with the latest price
     */
  function yourFunction(bytes[] calldata priceUpdate) public payable {
    // Submit a priceUpdate to the Pragma contract to update the on-chain price.
    // Updating the price requires paying the fee returned by getUpdateFee.
    uint fee = oracle.getUpdateFee(priceUpdate);
    oracle.updatePriceFeeds{ value: fee }(priceUpdate);
 
    // Read the current price from a price feed if it is less than 60 seconds old.
    // Each price feed (e.g., Spot Median ETH/USD) is identified by a unique identifier id.
    bytes32 id = ; // ETH/USD
    PragmaStructs.DataFeed memory data_feed = oracle.getSpotMedianNoOlderThan(id, 60);
  }

}

Let's detail the operations done by the snippet above. Firstly we instantiate a IPragma interface from the solidity SDK, linked to a Pragma contract, passed in the constructor.
Then we call IPragma.getUpdateFee to determine the fee charged to update the price.
After calling IPragma.updatePriceFeeds to update the price, paying the previous fee, we call IPragma.getSpotMedianNoOlderThan to read the current spot median price for the given feed id providing an acceptable staleness for the data to be fetched. You can find here the list of available feeds.

Integration by copying the Pragma interface​

Alternatively, you can copy the IPragma.sol interface and PragmaStructs.sol inside your repository, and generate an instance using a deployed Pragma contract.

import {IPragma} from "./interfaces/IPragma.sol";
import PragmaStructs from "./interfaces/PragmaStructs.sol";

The rest remains the same as described above.

Available feeds​

You can now use various methods to fetch data from the Pragma oracle. Here are the main functions:

  • getSpotMedianNoOlderThan(bytes32 id, uint256 age)
  • getTwapNoOlderThan(bytes32 id, uint256 age)
  • getRealizedVolatilityNoOlderThan(bytes32 id, uint256 age)
  • getOptionsNoOlderThan(bytes32 id, uint256 age)
  • getPerpNoOlderThan(bytes32 id, uint256 age)