eth_uninstallFilter | Polygon

Polygon API method used to remove a filter previously created using one of the following methods:

• eth_newFilter | Polygon
• eth_newPendingTransactionFilter | Polygon
• eth_newBlockFilter

Upon successful execution, the filter is removed and will no longer emit events.

This method can be useful for optimizing resource usage when a developer no longer needs to monitor certain events or blocks. It can also be used to clean up unused filters in order to reduce clutter in the client-side filter list.

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Disclaimer

Note that the default interactive example in this page will not work as the filter will be expired.

To test eth_uninstallFilter in this page, first create a new filter using one of the following:

• eth_newFilter | Polygon
• eth_newPendingTransactionFilter | Polygon
• eth_newBlockFilter

Then use the fresh filter ID as the parameter for eth_uninstallFilter.

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Parameters

• string — the filter ID that you want to uninstall

Response

• boolean — a boolean value indicating whether the filter was successfully uninstalled. true if successfully removed, and false if not.

eth_uninstallFilter code examples

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Note that the web3.eth.filter methods have been deprecated and replaced with the web3.eth.subscribe in web3.js. See web3.js subscriptions.

const ethers = require('ethers');
const NODE_URL = "CHAINSTACK_NODE_URL";
const provider = new ethers.JsonRpcProvider(NODE_URL);

async function removeFilter(filter) {
  try {
    const removed = await provider.send('eth_uninstallFilter', [filter]);
    console.log(removed); // Log whether the filter is removed
  } catch (err) {
    console.error(err); // Handle errors that may occur
  }
}

const filterId =  '0x4e7ef166cd43f188b0f8f9e218966a8f' //'YOUR_FILTER_iD'
removeFilter(filterId)

from web3 import Web3  
node_url = "CHAINSTACK_NODE_URL" 
web3 = Web3(Web3.HTTPProvider(node_url))

def remove_filter(filter_id):
    try:
        removed = web3.eth.uninstall_filter(filter_id)
        return removed
    except Exception as e:
        print(e)

filter_id = '0x0'
print(remove_filter(filter_id))

Use case

One use case for eth_uninstallFilter is to optimize resource usage in a DApp. When a DApp needs to monitor events on the blockchain, it can create a filter using eth_newFilter | Polygon, eth_newPendingTransactionFilter | Polygon , or eth_newBlockFilter to listen for specific events or blocks.

However, once the DApp no longer needs to monitor these events or blocks, it can use eth_uninstallFilter to stop watching for them. By doing so, the DApp can reduce the number of active filters and free up resources, such as network bandwidth and computational power, that would otherwise be used to maintain the filter.

For example, let's say that a DApp is monitoring incoming blocks, logs batches of 50 blocks, and then uses uninstallFilter to remove the filter using.

Here is an implementation of this concept using ethers.js:

const ethers = require('ethers');
const NODE_URL = "CHAINSTACK_NODE_URL";
const provider = new ethers.providers.JsonRpcProvider(NODE_URL);

const BLOCKS_TO_FETCH = 50;
const BLOCK_FETCH_INTERVAL_MS = 200;

async function getNewBlocks() {

  const filterId = await provider.send("eth_newBlockFilter", []);
  let blocks = [];
  while (blocks.length < BLOCKS_TO_FETCH) {
    const changes = await provider.send("eth_getFilterChanges", [filterId]);
    //console.log(changes) // show the changes

    if (changes.length === 0) {
      await new Promise(resolve => setTimeout(resolve, BLOCK_FETCH_INTERVAL_MS)); // wait for new blocks
      
    } else {
      blocks = blocks.concat(changes);
    }
  }
  const removeFilter = await provider.send("eth_uninstallFilter", [filterId]); // clean up filter
  if (removeFilter) {
    console.log(`We got 50 blocks, filter ${filterId} was removed.`)
    return blocks
  }
  
}

async function main() {
  const fiftyBlocks = await getNewBlocks();
  console.log(fiftyBlocks)
}

main()

This code fetches the latest 50 blocks using a filter and creates an array.

The BLOCKS_TO_FETCH constant is set to 50, which represents the number of blocks to fetch.

The BLOCK_FETCH_INTERVAL_MS constant is set to 200, which represents the time interval (in milliseconds) to wait for new blocks to arrive.

The getNewBlocks function is defined to fetch the blocks. This function uses a loop to retrieve new blocks until it has fetched the desired number of blocks. The loop waits for new blocks to arrive for a certain amount of time before trying again.

Inside the getNewBlocks function, the eth_newBlockFilter JSON-RPC method is called to create a new filter to watch for new blocks. The filter ID is returned and stored in the filterId variable. An array stores the blocks fetched.

Inside the loop, the eth_getFilterChanges | Polygon JSON-RPC method is called to retrieve any new blocks that have arrived since the filter was created. If there are no new blocks, the code waits a certain amount of time before trying again. If there are new blocks, they are stored in the blocks array.

Once the blocks array has reached the BLOCKS_TO_FETCH limit, the filter is uninstalled using the eth_uninstallFilter JSON-RPC method. The removeFilter variable is set to true if the filter is successfully removed. If the filter is removed successfully, a message is logged to the console indicating that BLOCKS_TO_FETCH blocks have been fetched and the filter was removed. The blocks array is returned as the result of the getNewBlocks function.

The main function is defined to call the getNewBlocks function and store the result in the fiftyBlocks variable. The fiftyBlocks variable is then logged to the console.

Try the eth_uninstallFilter RPC method yourself