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| 1 | +// Copyright 2019-2022 Parity Technologies (UK) Ltd. |
| 2 | +// This file is part of subxt. |
| 3 | +// |
| 4 | +// subxt is free software: you can redistribute it and/or modify |
| 5 | +// it under the terms of the GNU General Public License as published by |
| 6 | +// the Free Software Foundation, either version 3 of the License, or |
| 7 | +// (at your option) any later version. |
| 8 | +// |
| 9 | +// subxt is distributed in the hope that it will be useful, |
| 10 | +// but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | +// GNU General Public License for more details. |
| 13 | +// |
| 14 | +// You should have received a copy of the GNU General Public License |
| 15 | +// along with subxt. If not, see <http://www.gnu.org/licenses/>. |
| 16 | + |
| 17 | +//! To run this example, a local polkadot node should be running. Example verified against polkadot 0.9.13-82616422d0-aarch64-macos. |
| 18 | +//! |
| 19 | +//! E.g. |
| 20 | +//! ```bash |
| 21 | +//! curl "https://github.com/paritytech/polkadot/releases/download/v0.9.13/polkadot" --output /usr/local/bin/polkadot --location |
| 22 | +//! polkadot --dev --tmp |
| 23 | +//! ``` |
| 24 | +
|
| 25 | +use futures::StreamExt; |
| 26 | +use sp_keyring::AccountKeyring; |
| 27 | +use std::time::Duration; |
| 28 | +use subxt::{ |
| 29 | + ClientBuilder, |
| 30 | + DefaultConfig, |
| 31 | + DefaultExtra, |
| 32 | + PairSigner, |
| 33 | +}; |
| 34 | + |
| 35 | +#[subxt::subxt(runtime_metadata_path = "examples/polkadot_metadata.scale")] |
| 36 | +pub mod polkadot {} |
| 37 | + |
| 38 | +/// Subscribe to all events, and then manually look through them and |
| 39 | +/// pluck out the events that we care about. |
| 40 | +#[async_std::main] |
| 41 | +async fn main() -> Result<(), Box<dyn std::error::Error>> { |
| 42 | + env_logger::init(); |
| 43 | + |
| 44 | + let api = ClientBuilder::new() |
| 45 | + .build() |
| 46 | + .await? |
| 47 | + .to_runtime_api::<polkadot::RuntimeApi<DefaultConfig, DefaultExtra<DefaultConfig>>>(); |
| 48 | + |
| 49 | + // Subscribe to any events that occur: |
| 50 | + let mut event_sub = api.events().subscribe().await?; |
| 51 | + |
| 52 | + // While this subscription is active, balance transfers are made somewhere: |
| 53 | + async_std::task::spawn(async { |
| 54 | + let signer = PairSigner::new(AccountKeyring::Alice.pair()); |
| 55 | + let api = ClientBuilder::new() |
| 56 | + .build() |
| 57 | + .await |
| 58 | + .unwrap() |
| 59 | + .to_runtime_api::<polkadot::RuntimeApi<DefaultConfig, DefaultExtra<DefaultConfig>>>(); |
| 60 | + |
| 61 | + let mut transfer_amount = 1_000_000_000; |
| 62 | + |
| 63 | + // Make small balance transfers from Alice to Bob in a loop: |
| 64 | + loop { |
| 65 | + api.tx() |
| 66 | + .balances() |
| 67 | + .transfer(AccountKeyring::Bob.to_account_id().into(), transfer_amount) |
| 68 | + .sign_and_submit(&signer) |
| 69 | + .await |
| 70 | + .unwrap(); |
| 71 | + |
| 72 | + async_std::task::sleep(Duration::from_secs(10)).await; |
| 73 | + transfer_amount += 100_000_000; |
| 74 | + } |
| 75 | + }); |
| 76 | + |
| 77 | + // Our subscription will see the events emitted as a result of this: |
| 78 | + while let Some(events) = event_sub.next().await { |
| 79 | + let events = events?; |
| 80 | + let block_hash = events.block_hash(); |
| 81 | + |
| 82 | + // We can iterate, statically decoding all events if we want: |
| 83 | + println!("All events in block {block_hash:?}:"); |
| 84 | + println!(" Static event details:"); |
| 85 | + for event in events.iter() { |
| 86 | + let event = event?; |
| 87 | + println!(" {event:?}"); |
| 88 | + } |
| 89 | + |
| 90 | + // Or we can dynamically decode events: |
| 91 | + println!(" Dynamic event details: {block_hash:?}:"); |
| 92 | + for event in events.iter_raw() { |
| 93 | + let event = event?; |
| 94 | + let is_balance_transfer = event |
| 95 | + .as_event::<polkadot::balances::events::Transfer>()? |
| 96 | + .is_some(); |
| 97 | + let pallet = event.pallet; |
| 98 | + let variant = event.variant; |
| 99 | + println!( |
| 100 | + " {pallet}::{variant} (is balance transfer? {is_balance_transfer})" |
| 101 | + ); |
| 102 | + } |
| 103 | + |
| 104 | + // Or we can dynamically find the first transfer event, ignoring any others: |
| 105 | + let transfer_event = |
| 106 | + events.find_first_event::<polkadot::balances::events::Transfer>()?; |
| 107 | + |
| 108 | + if let Some(ev) = transfer_event { |
| 109 | + println!(" - Balance transfer success: value: {:?}", ev.amount); |
| 110 | + } else { |
| 111 | + println!(" - No balance transfer event found in this block"); |
| 112 | + } |
| 113 | + } |
| 114 | + |
| 115 | + Ok(()) |
| 116 | +} |
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