📂 dApp Developers
# readerCanReadDataFeed()
Table of Contents
For on-chain smart contracts, the function
readerCanReadDataFeed() (opens new window)
returns true if the reader parameter can access the dataFeedId parameter
meaning that the reader address has read access. See
Coverage Policies for more information about dAPI read
access.
# Example Usage
// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "@api3/airnode-protocol-v1/contracts/dapis/interfaces/IDapiServer.sol";
contract mySmartContract {
function myVerifyReadable(
address _dapiServerContractAddress,
bytes32 _datafeedId
) external {
bool private canRead;
// Calling the DapiServer for reader status
// where "this" is the contract address of this contract (myVerifyReadable).
(canRead) =
IDapiServer(_dapiServerContractAddress).readerCanReadDataFeed(_datafeedId, address(this));
}
}
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# Parameters
readerCanReadDataFeed(bytes32 datafeedId, address reader)
bytes32 datafeedId- The ID of a dAPI, Beacon, or Beacon set.address reader- The address to verify such as the reader's smart contract address or another address.
# Using a dapiName for the datafeedId parameter
If you want to check the status using a dapiName, first encode the dapiName
to bytes32 and calculate the off-chain hash of the encodedDapiName as shown
below. Then pass the value of dapiNameHash as _datafeedId in the code
example above. Try it in the
ethers playground (opens new window).
// First encode the dapiName (such as AVAX/USD) to bytes32
encodedDapiName = ethers.utils.formatBytes32String("AVAX/USD");
// encodedDapiName now equals
// 0x415641582f555344000000000000000000000000000000000000000000000000
// Then calculate the off-chain hash
dapiNameHash = ethers.utils.solidityKeccak256(['bytes32'], [encodedDapiName]);
// dapiNameHash now equals
// 0xcc06defee290c6e46f55823e39eb14024b06d4a6c7a0b6bf8b1f1e229c389b9c
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# Returns
bool- Whether the address passed is whitelisted and therefore can read the dAPI, Beacon, or Beacon set ID passed.