chain_getHeader - Midnight

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

This method returns the header of a block by its hash. Headers contain parent hash, number, state root, extrinsics root, and digest.

Parameters

Parameter

Type

Required

Description

hash

string

Block hash to query. Defaults to the current best block

Request Example

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "chain_getHeader",
    "params": [
        "0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"
    ],
    "id": "getblock.io"
}'

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "chain_getHeader",
    "params": [
        "0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"
    ],
    "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));

import requests
import json

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

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "chain_getHeader",
    "params": [
        "0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"
    ],
    "id": "getblock.io"
})

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

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

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_getHeader",
        "params": [
                "0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"
        ],
        "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": {
        "parentHash": "0x86e4c08\u2026",
        "number": "0xef727",
        "stateRoot": "0x9e7c5e\u2026",
        "extrinsicsRoot": "0x56e81f\u2026",
        "digest": {
            "logs": []
        }
    }
}

Response Parameters

Field

Type

Description

result.parentHash

string

Hash of the parent block

result.number

string

Block number (hex)

result.stateRoot

string

State trie root after this block

result.extrinsicsRoot

string

Extrinsics trie root

result.digest

object

Block digest with consensus logs

Use Cases

Light client header walks
Indexers that need only metadata
Verifying parent-chain relationships

Error Handling

Status Code

Error Message

Cause

403

Forbidden

Missing or invalid <ACCESS-TOKEN>

-32602

Invalid params

Request parameters are missing or malformed

429

Too Many Requests

Rate limit exceeded for your plan

SDK Integration

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

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

// Call via the typed API:
const result = await api.rpc.chain.getHeader("0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95");
console.log(result.toJSON());

// Or call the raw JSON-RPC method:
const raw = await api.rpc.rpc.methods();
// const raw = await (api as any)._rpcCore.provider.send('chain_getHeader', ["0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"]);

from substrateinterface import SubstrateInterface

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

# Generic RPC call:
result = substrate.rpc_request('chain_getHeader', ["0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"])
print(result)

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