eth_newBlockFilter | Arbitrum
Arbitrum API method that creates a filter that watches for new blocks on the blockchain. It returns a filter ID, which can be used to retrieve the results using the eth_getFilterChanges method. The eth_newBlockFilter
method is useful for developers who must be notified of new blocks on the blockchain in real time.
Get you own node endpoint today
Start for free and get your app to production levels immediately. No credit card required.
You can sign up with your GitHub, X, Google, or Microsoft account.
Parameters
none
Response
result
— a hexadecimal string representing the ID of the newly created filter
The filters created are stored on the blockchain client instance. The filter fill is automatically deleted if not polled within a certain time (5 minutes by default).
Use the following methods with the filter ID:
- eth_getFilterChanges to retrieve updates
- eth_uninstallFilter to remove the filter
eth_newBlockFilter
code examples
web3.eth.filterdeprecation
Note that the web3.eth.filter
methods have been deprecated and replaced with the web3.eth.subscribe
in web3.js. See web3.js subscriptions.
Use case
One use case for eth_newBlockFilter
in a simple DApp is to listen for new blocks and update the user interface with the latest block information.
When the DApp starts, it creates a new filter using eth_newBlockFilter
to listen for new blocks. When a new block is added to the blockchain, the filter is triggered, and the DApp retrieves the latest block information using a Web3 library.
Here is an implementation of this use case using web3.py:
The code is divided into three main functions: get_new_blocks
, watch_for_blocks
, and main
. Let’s take a closer look at each of them:
get_new_blocks
is responsible for setting up a new filter to watch for new blocks. The try
block sets up the filter by calling the eth.filter
method of the web3.py library and passing it the string latest
. The split
method is then used to split the resulting string at each space character, and the second part of the resulting list is extracted as the filter ID. The filter ID is returned from the function.
The eth.filter
method of the web3.py library does not only return the filter ID but it returns a sentence saying Filter for 0x3c3f5a5e637d29c033e4e7a3f7e870cd
. This is the reason for the string manipulation within the get_new_blocks
function.
watch_for_blocks
is the function that watches for new blocks. It does this by first entering an infinite loop while True
. Within this loop, the eth_getFilterChanges method is used to retrieve any changes that match the filter ID passed to the function. If there are no changes, the code waits for 1 second using the time.sleep
method and then continues with the loop. If there are changes, the new blocks are processed by looping through them and calling the eth.getBlock
method of the web3.py library to retrieve the details of each block. Finally, the details of the new blocks are printed on the console.
main
is the function that ties everything together. It first calls get_new_blocks
to set up a new filter to watch for new blocks, and then passes the resulting filter ID to watch_for_blocks
to start watching for new blocks. The filter ID is also printed to the console to confirm that the filter has been set up correctly.