eth_getFilterChanges - Polygon

Example code for the eth_getFilterChanges json-rpc method. Сomplete guide on how to use eth_getFilterChanges json-rpc in GetBlock.io Web3 documentation.

The eth_getFilterChanges method polls for logs or changes since the last poll. The filter must have been created with eth_newFilter, eth_newBlockFilter, or eth_newPendingTransactionFilter.

Parameters

Parameter	Type	Required	Description
filterId	string	Yes	The filter ID returned by filter creation methods

Request

cURL

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_getFilterChanges",
    "params": ["0x1"],
    "id": "getblock.io"
}'

Axios

JavaScript (Axios)

import axios from 'axios';

const url = 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/';

const payload = {
    jsonrpc: '2.0',
    method: 'eth_getFilterChanges',
    params: ["0x1"],
    id: 'getblock.io'
};

axios.post(url, payload, {
    headers: { 'Content-Type': 'application/json' }
})
.then(response => console.log(response.data))
.catch(error => console.error(error));

Request

Python (requests)

import requests

url = "https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/"

payload = {
    "jsonrpc": "2.0",
    "method": "eth_getFilterChanges",
    "params": ["0x1"],
    "id": "getblock.io"
}

response = requests.post(url, headers={"Content-Type": "application/json"}, json=payload)
print(response.json())

Rust

Rust (reqwest)

use reqwest::header;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = reqwest::Client::new();
    
    let response = client
        .post("https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header(header::CONTENT_TYPE, "application/json")
        .body(r#"{
            "jsonrpc": "2.0",
            "method": "eth_getFilterChanges",
            "params": ["0x1"],
            "id": "getblock.io"
        }"#)
        .send()
        .await?;
    
    println!("{}", response.text().await?);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": []
}

Response Parameters

Field	Type	Description
jsonrpc	string	JSON-RPC version (2.0)
id	string	Request identifier
result	varies	Array of log objects, block hashes, or transaction hashes depending on filter type

Use Case

The eth_getFilterChanges method is useful for:

• Event monitoring

• Real-time updates

• Log polling

• Block notifications

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid ACCESS-TOKEN
-32600	Invalid Request	Malformed request body
-32602	Invalid params	Invalid method parameters

Web3 Integration

First Tab

Ethers.js

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

const result = await provider.send('eth_getFilterChanges', ["0x1"]);
console.log('Result:', result);

Viem

Viem

import { createPublicClient, http } from 'viem';
import { polygon } from 'viem/chains';

const client = createPublicClient({
    chain: polygon,
    transport: http('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')
});

const result = await client.request({
    method: 'eth_getFilterChanges',
    params: ["0x1"]
});
console.log('Result:', result);