chain_getBlock - Polkadot

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

This method returns a full block by its hash, including the header and the SCALE-encoded extrinsics it contains. If no hash is supplied, the latest block is returned.

Parameters

Parameter	Type	Required	Description
hash	string	No	Block hash. Defaults to the latest block when omitted

Request

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{"jsonrpc": "2.0", "method": "chain_getBlock", "params": ["0x255bc00927df8d33d561792635cbc6bde480a0a505eef5ff28630ece3fc15b32"], "id": "getblock.io"}'

JavaScript

example.js

const response = await fetch('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
        jsonrpc: '2.0',
        method: 'chain_getBlock',
        params: ["0x255bc00927df8d33d561792635cbc6bde480a0a505eef5ff28630ece3fc15b32"],
        id: 'getblock.io'
    })
});

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

Python

example.py

import requests

response = requests.post(
    'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'chain_getBlock',
        'params': ["0x255bc00927df8d33d561792635cbc6bde480a0a505eef5ff28630ece3fc15b32"],
        'id': 'getblock.io'
    }
)

print(response.json()['result'])

Response

{
    "id": "getblock.io",
    "jsonrpc": "2.0",
    "result": {
        "block": {
            "extrinsics": [
                "0x280403000b406017cb7b01"
            ],
            "header": {
                "digest": {
                    "logs": [
                        "0x0642414245b5010392...",
                        "0x0542414245010114a5..."
                    ]
                },
                "extrinsicsRoot": "0xada254ef8321e28a6667ad75659be6464944174bd5540667da94590a0a4a596f",
                "number": "0x67103a",
                "parentHash": "0x570e3f417a41646d9b978bf2ac3d68be48bb0f73082825f438af58a37cfe0ef8",
                "stateRoot": "0x176c67eca385c24403ba774550ff75dcfa652d6d6cf2d2ecbccf56e513db601c"
            }
        },
        "justifications": null
    }
}

Response Parameters

Parameter	Type	Description
id	string	Request identifier matching the request
jsonrpc	string	JSON-RPC protocol version ("2.0")
result	object	Signed block object with its header and extrinsics

block.header

Field	Type	Description
parentHash	string	Hash of the parent block header
number	string	Block number, hex-encoded
stateRoot	string	Root hash of the state trie after the block
extrinsicsRoot	string	Root hash of the extrinsics trie
digest	object	Consensus digest logs (BABE, GRANDPA, and others)

block

Field	Type	Description
extrinsics	array	SCALE-encoded extrinsics in the block
header	object	The block header

Use Cases

• Block Explorers: Render a block's header and extrinsics

• Chain Indexing: Ingest blocks and decode their extrinsics

• Transaction Tracing: Locate an extrinsic within a block

• Auditing: Read the raw contents of a specific block

Error Handling

Error Code	Message	Description
-32602	Invalid params	A parameter is missing or has the wrong type or format
-32601	Method not found	The method is not available on this endpoint
-32603	Internal error	The node failed to process the request

Library Integration

The idiomatic way to call Polkadot RPC is the Polkadot.js API (@polkadot/api), which connects over WebSocket and exposes the method as api.rpc.chain.getBlock.

polkadot-js.js

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

const provider = new WsProvider('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');
const api = await ApiPromise.create({ provider });

const result = await api.rpc.chain.getBlock('0x255bc00927df8d33d561792635cbc6bde480a0a505eef5ff28630ece3fc15b32');
console.log(result.toHuman());