eth_getFilterChanges

Polling method for a filter, which returns an array of events that have occurred since the last poll on the Centrifuge network.

Parameters

• id (string, required): The filter ID returned from eth_newFilter, eth_newBlockFilter, or eth_newPendingTransactionFilter

Returns

An array containing different data types depending on the filter type:

For log filters (eth_newFilter):

Array of log objects with:

• address (string): Address from which this log originated
• topics (array of strings): Array of 0 to 4 32-byte DATA topics
• data (string): Contains non-indexed arguments of the log
• blockNumber (string): Block number where this log was included
• blockHash (string): Hash of the block where this log was included
• transactionHash (string): Hash of the transaction that created this log
• transactionIndex (string): Transaction index position in the block
• logIndex (string): Integer of the log index position in the block
• removed (boolean): true when the log was removed due to a chain reorganization

For block filters (eth_newBlockFilter):

Array of 32-byte block hashes for blocks that were newly created

For pending transaction filters (eth_newPendingTransactionFilter):

Array of 32-byte transaction hashes for transactions that entered the pending state

Implementation Example

cURL

# Create a log filter scoped to the latest block (requires jq)
FILTER_ID=$(curl -s -X POST https://api-centrifuge.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_newFilter",
    "params": [{
      "fromBlock": "latest",
      "toBlock": "latest",
      "address": null,
      "topics": []
    }],
    "id": 1
  }' | jq -r '.result')

# Poll for changes on that filter
curl -s -X POST https://api-centrifuge.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d "$(jq -n --arg id \"$FILTER_ID\" '{jsonrpc:\"2.0\", method:\"eth_getFilterChanges\", params:[$id], id:1}')"

JavaScript

const endpoint = 'https://api-centrifuge.n.dwellir.com/YOUR_API_KEY';

const createFilter = async () => {
  const filterResponse = await fetch(endpoint, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      jsonrpc: '2.0',
      method: 'eth_newFilter',
      params: [{ fromBlock: 'latest', toBlock: 'latest', address: null, topics: [] }],
      id: 1
    })
  });
  const { result } = await filterResponse.json();
  return result;
};

const filterId = await createFilter();
const response = await fetch(endpoint, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    jsonrpc: '2.0',
    method: 'eth_getFilterChanges',
    params: [filterId],
    id: 2
  })
});

const data = await response.json();
console.log(data.result);

Python

import requests

url = 'https://api-centrifuge.n.dwellir.com/YOUR_API_KEY'
headers = {'Content-Type': 'application/json'}

filter_payload = {
    "jsonrpc": "2.0",
    "method": "eth_newFilter",
    "params": [{
        "fromBlock": "latest",
        "toBlock": "latest",
        "address": None,
        "topics": []
    }],
    "id": 1
}

filter_id = requests.post(url, headers=headers, json=filter_payload, timeout=10).json()['result']

changes_payload = {
    "jsonrpc": "2.0",
    "method": "eth_getFilterChanges",
    "params": [filter_id],
    "id": 2
}

response = requests.post(url, headers=headers, json=changes_payload, timeout=10)
print(response.json()['result'])

Response Example

For log filters:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": [
    {
      "address": "0x1234567890abcdef1234567890abcdef12345678",
      "topics": [
        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
      ],
      "data": "0x0000000000000000000000000000000000000000000000000de0b6b3a7640000",
      "blockNumber": "0x1b4",
      "blockHash": "0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890",
      "transactionHash": "0xfedcba0987654321fedcba0987654321fedcba0987654321fedcba0987654321",
      "transactionIndex": "0x1",
      "logIndex": "0x0",
      "removed": false
    }
  ]
}

For block filters:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": [
    "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
    "0xfedcba0987654321fedcba0987654321fedcba0987654321fedcba0987654321"
  ]
}

Notes

• This method only returns changes that occurred since the last poll
• Filters timeout if not accessed within a certain time period (typically 5 minutes)
• The first call to eth_getFilterChanges returns all events since filter creation
• Subsequent calls return only new events since the previous call
• Use eth_getFilterLogs to retrieve all accumulated logs regardless of polling

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Need help? Contact our support team or check the Centrifuge documentation.