getmempooldescendants - Bitcoin Cash

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

This method returns the in-mempool descendants of a transaction: the unconfirmed transactions that depend on it. Verbose mode returns full entry data for each descendant.

Parameters

Parameter	Type	Required	Description
txid	string	Yes	The transaction id, which must be in the mempool
verbose	boolean	No	true for detailed objects, false for an array of txids. Default false

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "getmempooldescendants",
    "params": ["10b54fd708ab2e5703979b4ba27ca0339882abc2062e77fbe51e625203a49642", false],
    "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: 'getmempooldescendants',
  params: ['10b54fd708ab2e5703979b4ba27ca0339882abc2062e77fbe51e625203a49642', false], 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': 'getmempooldescendants',
        'params': ["10b54fd708ab2e5703979b4ba27ca0339882abc2062e77fbe51e625203a49642", false],
        '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": "getmempooldescendants",
            "params": ["10b54fd708ab2e5703979b4ba27ca0339882abc2062e77fbe51e625203a49642", false],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

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

Response

{
    "error": null,
    "id": "getblock.io",
    "result": [
        "780791bb2d5a8ccda4b5a707967a8e15b412814852c58c77299e85579bb65587"
    ]
}

Response Parameters

Parameter	Type	Description
error	null|object	Error object when the call fails, otherwise null
id	string	Request identifier matching the request
result	array|object	Array of descendant txids, or detailed objects when verbose is true

Use Cases

• Impact Analysis: See which unconfirmed transactions depend on a given one

• Eviction Risk: Assess how many descendants would be affected by an eviction

• Fee Bumping: Account for descendants when computing effective fee rates

• Chain Limits: Check descendant counts against mempool chain limits

Error Handling

Error Code	Message	Description
-8	Invalid parameter	txid is not a valid 64-character hex string
-5	Transaction not found	No transaction with the given id is available; a txindex may be required
-32603	Internal error	Node failed to read the transaction