# readDataFeedValueWithDapiName()

Table of Contents

This function reads a value from a dAPI using its name. In the code example below, \_dapiNameis a dAPI name. For on-chain smart contracts the msg.sender argument received by the function readDataFeedValueWithDapiName() (opens new window) must have read access for the dAPI requested.

Calling from off-chain code (using a library such as ether.js) is not subject to coverage policies. Off-chain code is beyond the scope of this doc.

# Example Usage

// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "@api3/airnode-protocol-v1/contracts/dapis/interfaces/IDapiServer.sol";
contract mySmartContract {
    function myGetDataFeedValue(
        address _dapiServerContractAddress,
        bytes32 _dapiName
    ) external {
        int224 private value;
        // Calling the DapiServer for a data feed value.
        value =
            IDapiServer(_dapiServerContractAddress).readDataFeedValueWithDapiName(_dapiName);
    }
}

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See another code example of readDataFeedValueWithDapiName() in the data-feed-reader-example repo (opens new window).

# Parameters

readDataFeedValueWithDapiName(bytes32 _dapiName)

bytes32 dapiName - The encoded bytes32 value of a dAPI name to retrieve a value for (no timestamp). The example below generates the encoded bytes32 value of AVAX/USD. Try it in the ethers playground (opens new window).

// Encode the dapiName (such as AVAX/USD) to bytes32
ethers.utils.formatBytes32String("AVAX/USD");
// 0x415641582f555344000000000000000000000000000000000000000000000000
// Pass the above value to readDataFeedWithDapiName()

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# Returns

int224 value - The value of the dAPI.

Please note:

The DapiServer.sol contract casts the reported data point to int224. If this is a problem (because the reported data may not fit into 224 bits or it is of a completely different type such as bytes32), do not use this contract and implement a customized version instead. The contract casts the timestamps to uint32, which means it will not work work past-2106 in the current form. If this is an issue, consider casting the timestamps to a larger type.

If the timestamp is 0 then the function will revert with "Data feed does not exist".

← readDataFeedWithDapiName() readDataFeedWithId() →