state_callAt - Midnight

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

This method executes a runtime API call at a specific historical block. Same semantics as state_call, but at a chosen block hash.

Parameters

Parameter

Type

Required

Description

name

string

Yes

Runtime API method name

bytes

string

Yes

SCALE-encoded call parameters (hex)

hash

string

Yes

Block hash at which to execute

Request Example

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

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "state_callAt",
    "params": [
        "Core_version",
        "0x",
        "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": "state_callAt",
    "params": [
        "Core_version",
        "0x",
        "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": "state_callAt",
        "params": [
                "Core_version",
                "0x",
                "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": "0x206d69646e696768742060\u2026"
}

Response Parameters

Field

Type

Description

result

string

SCALE-encoded return value (hex)

Use Cases

Reading runtime state at historical heights
Replaying typed queries across blocks
Auditing state changes between block heights

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

The method is not enabled on this node or has been deprecated

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.state.callAt("Core_version", "0x", "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('state_callAt', ["Core_version", "0x", "0x87f5c08ba8334e4ee1642ff9646e94dd46080b71fff03714be8b36f22e481b95"]);

from substrateinterface import SubstrateInterface

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

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

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