Chain-Data Query

Learn how to connect to Filecoin RPC nodes and query Filecoin chain state and data.

Connecting to Filecoin networks via public RPC nodes

To query chain state and data on any Filecoin network, it is necessary to connect to public node providers. However, it's important to note that most public node providers offer limited access, typically allowing read-only JSON RPC calls and MPoolPush to send signed messages to the Filecoin networks.

To explore further details about the available public RPC providers supporting Filecoin mainnet and Calibration testnet, you can refer to the following page.

• Filecoin mainnet RPCs

• Filecoin Calibration testnet RPCs

Ingredients

Let's use Glif nodes as an example to demonstrate how to connect to a public Filecoin RPC node provider. Additionally, we will utilize ethers.js to establish the connection with the RPC nodes.

• Glif nodes

• ethers.js

Instructions

We will use ethers.js to establish a connection with the public Filecoin node provided by Glif. The following code demonstrates connecting to the Filecoin Calibration testnet as an example.

import { ethers } from "ethers"

//The public Filecoin calibration URL
const filecoin_url = 'https://api.calibration.node.glif.io/rpc/v1'
const provider = new ethers.JsonRpcProvider(filecoin_url)

const blockNumber = await provider.getBlockNumber()
console.log("Block height: ", blockNumber)

The expected output:

Block height:  1268350

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Listen to smart contract events

Since the Filecoin Virtual Machine (FVM) is EVM-compatible, we can use ethers.js to listen to smart contract events for specific contract actions on the Filecoin network. For instance, we can monitor ERC20 token transfer events or client contract DealProposalCreate events.

Ingredients

We will also use ethers.js to connect to the public Glif node to listen to the smart contract events.

• Glif Nodes

• ethers.js

Instructions

Let's consider the wFIL contract, an ERC-20 token on Filecoin, as an example for listening to its transfer event. To demonstrate how to listen to smart contract events using ethers, we will use the deployed wFIL token address on the Filecoin calibration network and a simplified ABI object for the transfer event. Typically, you would have the wFIL smart contract's Application Binary Interface (ABI) defined in an abi.json file.

The code to listen to transfer events for the wFIL token.

import { ethers } from "ethers"

const wFILAddress = "0xaC26a4Ab9cF2A8c5DBaB6fb4351ec0F4b07356c4" // wFIL Contract
var abi = ["event Transfer(address indexed from, address indexed to, uint amount)"]

const filecoin_url = 'https://api.calibration.node.glif.io/rpc/v1'
const provider = new ethers.providers.JsonRpcProvider(filecoin_url)

//listen to the Transfer events in the Token contract
const wFIL = new ethers.Contract(wFILAddress, abi, provider)
wFIL.on("Transfer", (from, to, value, event)=>{
    let transferEvent ={
        from: from,
        to: to,
        value: value,
        eventData: event,
    }
    console.log(JSON.stringify(transferEvent, null, 4))
})

Once a wFIL token transfer is executed on the blockchain, the following code snippet will capture the corresponding events and print out the event details.

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Filter smart contract events

We can also use filters to retrieve specific smart contract transactions from the Filecoin network. Filters enable us to define criteria or conditions to search for event logs that match specific requirements. By setting up a filter, we can monitor and retrieve event logs related to our interests or specific smart contracts.

Ingredients

We will also use ethers.js to connect to the public Glif node to filter the smart contract events by providing conditions.

• Glif nodes

• ethers.js

Instructions

Here's an example of how you can connect to a Glif node on the calibration network, create a filter to list all wFIL token transfers from your address, and execute the filter to look back 2000 blocks to find the matched transaction list:

import { ethers } from "ethers"

const wFILAddress = "0xaC26a4Ab9cF2A8c5DBaB6fb4351ec0F4b07356c4" // wFIL Contract
var abi = ["event Transfer(address indexed from, address indexed to, uint amount)"]

const filecoin_url = 'https://api.calibration.node.glif.io/rpc/v1'
const provider = new ethers.providers.JsonRpcProvider(filecoin_url)

// Create a filter to list all token transfers from myAddress
const filter = contract.filters.Transfer("0xd388aB098ed3E84c0D808776440B48F685198498");

//Filter on the events back to 2000 blocks. 
const currentBlockHight = await provider.getBlockNumber();
const result = await contract.queryFilter(filter,currentBlockHight-2000, currentBlockHight );
console.log(result);

The expected transaction will be similar as follows. With this information, you can develop custom logic to efficiently track and process specific events or blocks on your FEVM smart contracts.

{
    blockNumber: 1268728,
    blockHash: '0x7b4f34d3f7ef791da7f9ab1c342cf147eedf7ec4f99fe92b94a9372927779961',
    transactionIndex: 0,
    removed: false,
    address: '0xb44cc5FB8CfEdE63ce1758CE0CDe0958A7702a16',
    data: '0x0000000000000000000000000000000000000000000000001bc16d674ec80000',
    topics: [
      '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
      '0x000000000000000000000000d388ab098ed3e84c0d808776440b48f685198498',
      '0x00000000000000000000000044061aa8df5b33a997ce97d80c700d0c655dc3f2'
    ],
    transactionHash: '0x7adb72ac19bf6baa5176f5da799128140ea3a9a9306bf6b1ff52edc58c621c4b',
    logIndex: 0,
    removeListener: [Function (anonymous)],
    getBlock: [Function (anonymous)],
    getTransaction: [Function (anonymous)],
    getTransactionReceipt: [Function (anonymous)],
    event: 'Transfer',
    eventSignature: 'Transfer(address,address,uint256)',
    decode: [Function (anonymous)],
    args: [
      '0xd388aB098ed3E84c0D808776440B48F685198498',
      '0x44061AA8Df5b33a997CE97d80c700d0C655Dc3f2',
      [BigNumber],
      from: '0xd388aB098ed3E84c0D808776440B48F685198498',
      to: '0x44061AA8Df5b33a997CE97d80c700d0C655Dc3f2',
      amount: [BigNumber]
    ]
  },

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