pezkuwi-subxt/examples/examples/subscribe_blocks.rs

// Copyright 2019-2022 Parity Technologies (UK) Ltd.
// This file is dual-licensed as Apache-2.0 or GPL-3.0.
// see LICENSE for license details.

//! To run this example, a local polkadot node should be running. Example verified against polkadot 0.9.29-41a9d84b152.
//!
//! E.g.
//! ```bash
//! curl "https://github.com/paritytech/polkadot/releases/download/v0.9.29/polkadot" --output /usr/local/bin/polkadot --location
//! polkadot --dev --tmp
//! ```

use futures::StreamExt;
use subxt::{
    OnlineClient,
    PolkadotConfig,
};

#[subxt::subxt(runtime_metadata_path = "../artifacts/polkadot_metadata.scale")]
pub mod polkadot {}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    tracing_subscriber::fmt::init();

    // Create a client to use:
    let api = OnlineClient::<PolkadotConfig>::new().await?;

    // Subscribe to all finalized blocks:
    let mut blocks_sub = api.blocks().subscribe_finalized().await?;

    while let Some(block) = blocks_sub.next().await {
        let block = block?;

        let block_number = block.header().number;
        let block_hash = block.hash();

        println!("Block #{block_number}:");
        println!("  Hash: {block_hash}");
        println!("  Extrinsics:");

        let body = block.body().await?;
        for ext in body.extrinsics() {
            let idx = ext.index();
            let events = ext.events().await?;
            let bytes_hex = format!("0x{}", hex::encode(ext.bytes()));

            println!("    Extrinsic #{idx}:");
            println!("      Bytes: {bytes_hex}");
            println!("      Events:");

            for evt in events.iter() {
                let evt = evt?;

                let pallet_name = evt.pallet_name();
                let event_name = evt.variant_name();

                println!("        {pallet_name}_{event_name}");
            }
        }
    }

    Ok(())
}