preciousblock - Bitcoin Cash

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

This method treats a block as if it were received before others with the same work, influencing which chain the node considers active during a tie.

Parameters

Parameter	Type	Required	Description
blockhash	string	Yes	The hash of the block to mark as precious

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "preciousblock",
    "params": ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc"],
    "id": "getblock.io"
}'

bitcoinjs-lib

example.js

const axios = require('axios');
const { data } = await axios.post('https://go.getblock.io/<ACCESS-TOKEN>/', {
  jsonrpc: '2.0', method: 'preciousblock',
  params: ['0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc'], id: 'getblock.io'
});
console.log(data.result);

Request

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'preciousblock',
        'params': ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc"],
        'id': 'getblock.io'
    }
)

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

Rust

example.rs

use reqwest::Client;
use serde_json::{json, Value};

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

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "preciousblock",
            "params": ["0000000000000000023a561e1ea370153aac5d1504726d1a039032831c05fcfc"],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "error": null,
    "id": "getblock.io",
    "result": null
}

Response Parameters

Parameter	Type	Description
error	null|object	Error object when the call fails, otherwise null
id	string	Request identifier matching the request
result	null	null on success

Use Cases

• Fork Resolution: Prefer a specific block when two branches have equal work

• Node Recovery: Steer a node back onto the intended chain after a split

• Testing: Force chain selection in controlled test scenarios

• Consensus Debugging: Investigate reorg behaviour by biasing tip selection

Error Handling

Error Code	Message	Description
-8	Invalid parameter	blockhash is not a valid 64-character hex string
-5	Block not found	No block with the given hash exists on this node
-32603	Internal error	Node failed to read the block from disk