chain_getBlockHash - Bittensor

Example code for the chain_getBlockHash JSON-RPC method. Complete guide on how to use chain_getBlockHash JSON-RPC in GetBlock Web3 documentation.

Returns the block hash for a given block number. Without parameters, returns the latest block hash.

Substrate native JSON-RPC method. Call against a GetBlock endpoint configured for the Substrate interface. For typed SDK access, use Polkadot.js (TypeScript) or substrateinterface (Python).

Parameters

Parameter	Type	Required	Description
blockNumber	integer	No	Block number. Omit for the latest block.

Request Example

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "chain_getBlockHash",
    "params": [
        5870042
    ],
    "id": "getblock.io"
}'

JavaScript (Axios)

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "chain_getBlockHash",
    "params": [
        5870042
    ],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));

Python (Requests)

import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "chain_getBlockHash",
    "params": [
        5870042
    ],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)

Rust (Reqwest)

use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "chain_getBlockHash",
        "params": [
                5870042
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);

    Ok(())
}

Response Example

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0xc0a6cfca5d4f9e1cb8a5c4b3d2e7a9c4f1b8e6d5c3a2b1f9e8d7c6b5a4f3e2d1c"
}

Response Parameters

Field	Type	Description
result	string	Hex-encoded block hash

Use Cases

• Converting block number to hash for chain_getBlock / chain_getHeader queries

• Building chain-tip awareness in indexers

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
-32602	Invalid params	Request parameters are missing or malformed
-32601	Method not found	Method does not exist on this interface — check whether you're calling a Substrate method on an EVM endpoint or vice versa
-32603	Internal error	Server-side error while processing the request
429	Too Many Requests	Rate limit exceeded for your plan

SDK Integration

Polkadot.js (TypeScript)

import { ApiPromise, WsProvider } from '@polkadot/api';

const provider = new WsProvider('wss://go.getblock.io/<ACCESS-TOKEN>/');
const api = await ApiPromise.create({ provider });

// Typed wrapper: api.rpc.chain.getBlockHash(...)
const result = await api.rpc.chain.getBlockHash(5870042);
console.log(result.toHuman());

// Or use the raw RPC interface for any method:
// const raw = await api.rpc.send({ method: 'chain_getBlockHash', params: [5870042] });

substrateinterface (Python)

from substrateinterface import SubstrateInterface

substrate = SubstrateInterface(url="wss://go.getblock.io/<ACCESS-TOKEN>/")

# Generic RPC call:
result = substrate.rpc_request("chain_getBlockHash", [5870042])
print(result)