Alchemy SDKSDK V2 Methods

getLogs - SDK

Returns an array of logs that match the provided filter.

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Description

Returns an array of logs that match the provided filter.

Parameters

NameTypeDescription
filterobjectThe filter object to use. Includes the fromBlock and the toBlock.

filter parameters

ParameterTypeDescription
fromBlockstringEither the hex value of a block number OR One of the block tags listed below.
toBlockstringEither the hex value of a block number OR One of the block tags listed below:
  • pending (Not available on Ethereum) - A sample next block built by the client on top of latest and containing the set of transactions usually taken from local mempool. Intuitively, you can think of these as blocks that have not been mined yet.
  • latest - The most recent block in the canonical chain observed by the client, this block may be re-orged out of the canonical chain even under healthy/normal conditions.
  • safe - The most recent crypto-economically secure block, cannot be re-orged outside of manual intervention driven by community coordination. Intuitively, this block is “unlikely” to be re-orged. Only available on Ethereum Goerli.
  • finalized - The most recent crypto-economically secure block, that has been accepted by >2/3 of validators. Cannot be re-orged outside of manual intervention driven by community coordination. Intuitively, this block is very unlikely to be re-orged. Only available on Ethereum Goerli.
  • earliest - The lowest numbered block the client has available. Intuitively, you can think of this as the first block created.

Response

PropertyTypeDescription
Promise<Array<Log>>arrayArray of log objects, or an empty array if nothing has changed since the last poll.

<Array<Log>> response object parameters

PrameterTypeDescription
blockHashstring32 Bytes - hash of the block where this log was in. null when its pending. null when its pending log.
blockNumberintegerThe block number where this log was in. null when its pending. null when its pending log.
transactionIndexintegerInteger of the transactions index position log was created from. null when its pending log.
addressstring20 Bytes - address from which this log originated.
logIndexintegerInteger of the log index position in the block. null when its pending log.
datastringContains one or more 32 Bytes non-indexed arguments of the log.
removedbooleantrue when the log was removed, due to a chain reorganization. false if its a valid log.
topicsarray of stringsArray of zero to four 32 Bytes DATA of indexed log arguments. In solidity: The first topic is the hash of the signature of the event (e.g. Deposit(address,bytes32,uint256)), except you declare the event with the anonymous specifier.
transactionHashstringHash of the transactions this log was created from. null when its pending log.

Example Request and Response

Prerequisite: You will need to install the Alchemy SDK before making requests with it.

The commands for installing it using npm or yarn are given below:

$npm install alchemy-sdk

Request

Here is an example of how to make a getLogs request using the Alchemy SDK:

getlogs.js
1// Imports the Alchemy SDK
2const { Alchemy, Network } = require("alchemy-sdk");
3
4// Configures the Alchemy SDK
5const config = {
6    apiKey: "alchemy-replit", // Replace with your API key
7    network: Network.ETH_MAINNET, // Replace with your network
8};
9
10// Creates an Alchemy object instance with the config to use for making requests
11const alchemy = new Alchemy(config);
12
13const main = async () => {
14    //Initialize variables for the parameters
15    let address = "0xdAC17F958D2ee523a2206206994597C13D831ec7"
16    let topics =  [ "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef" ]
17    let blockHash = "0x49664d1de6b3915d7e6fa297ff4b3d1c5328b8ecf2ff0eefb912a4dc5f6ad4a0"
18    
19    //Call the method to return array of logs
20    let response = await alchemy.core.getLogs(address, topics, blockHash)
21
22    //Logging the response to the console
23    console.log(response)
24};
25
26main();

Response

shell
${
>    blockNumber: 16701233,
>    blockHash: '0x2bdfc733ded7277d23e9859455609b5deadc2fe3cc404e25ed6f6667ab271b42',
>    transactionIndex: 25,
>    removed: false,
>    address: '0x7Fc66500c84A76Ad7e9c93437bFc5Ac33E2DDaE9',
>    data: '0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
>    topics: [
>      '0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925',
>      '0x00000000000000000000000015891db79f767e4ace21f4e511cdb72008dc9fca',
>      '0x000000000000000000000000a3a7b6f88361f48403514059f1f16c8e78d60eec'
>    ],
>    transactionHash: '0xe8479758b8dd54f529187da4109898d5e89db2fd2fade7073b24cfe99dcf1d14',
>    logIndex: 40
>  },
>  {
>    blockNumber: 16701233,
>    blockHash: '0x2bdfc733ded7277d23e9859455609b5deadc2fe3cc404e25ed6f6667ab271b42',
>    transactionIndex: 29,
>    removed: false,
>    address: '0xdAC17F958D2ee523a2206206994597C13D831ec7',
>    data: '0x0000000000000000000000000000000000000000000000000000000023c34600',
>    topics: [
>      '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
>      '0x000000000000000000000000f097b3c3598692811e14a6fe6a4cf030df5d73eb',
>      '0x000000000000000000000000debb5b7df78c148694b9ca1fce6f9b2b0e584899'
>    ],
>    transactionHash: '0xf638486c1a9e76bcb66f92bcf58439dad9c3ea3a2cde41c33769713479148828',
>    logIndex: 41
>  },
>  {
>    blockNumber: 16701233,
>    blockHash: '0x2bdfc733ded7277d23e9859455609b5deadc2fe3cc404e25ed6f6667ab271b42',
>    transactionIndex: 32,
>    removed: false,
>    address: '0x514910771AF9Ca656af840dff83E8264EcF986CA',
>    data: '0x0000000000000000000000000000000000000000000000017085b53104e2e000',
>    topics: [
>      '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
>      '0x000000000000000000000000dfd5293d8e347dfe59e90efd55b2956a1343963d',
>      '0x000000000000000000000000787afa42f5d0e0b34189ad4d8b47ba87f615b416'
>    ],
>    transactionHash: '0xa5c97ea24020ad959708886007e95df5eb5778c70d1a34e0c3dc18bd7de9225a',
>    logIndex: 42
>  }, ......................

Use Cases

Here are some possible use cases for the getLogs method:

  • Event tracking: getLogs can be used to track specific events generated by smart contracts. This is useful for monitoring the state changes of a smart contract and taking action based on those changes.

  • Analytics: getLogs can be used to analyze smart contract data and generate reports or visualizations. For example, you could use getLogs to analyze the frequency and volume of trades on a decentralized exchange.

  • Debugging: getLogs can be used to debug smart contracts. If a smart contract is not behaving as expected, you can use getLogs to retrieve the events generated by the contract and identify where the issue is occurring.

Related Methods

Here are the methods related to getLogs:

  • getBlock -SDK: Returns the block from the network based on the provided block number or hash.