50 lines
2.1 KiB
Rust
50 lines
2.1 KiB
Rust
// Copyright 2019-2025 Parity Technologies (UK) Ltd.
|
|
// This file is dual-licensed as Apache-2.0 or GPL-3.0.
|
|
// see LICENSE for license details.
|
|
|
|
//! # Events
|
|
//!
|
|
//! In the process of adding extrinsics to a block, they are executed. When extrinsics are executed,
|
|
//! they normally produce events describing what's happening (at the very least, an event dictating whether
|
|
//! the extrinsic has succeeded or failed). The node may also emit some events of its own as the block is
|
|
//! processed.
|
|
//!
|
|
//! Events live in a single location in node storage which is overwritten at each block. Normal nodes tend to
|
|
//! keep a snapshot of the state at a small number of previous blocks, so you can sometimes access
|
|
//! older events by using [`crate::events::EventsClient::at()`] and providing an older block hash.
|
|
//!
|
|
//! When we submit transactions using Subxt, methods like [`crate::tx::TxProgress::wait_for_finalized_success()`]
|
|
//! return [`crate::blocks::ExtrinsicEvents`], which can be used to iterate and inspect the events produced
|
|
//! by that transaction being executed. We can also access _all_ of the events produced in a single block using one
|
|
//! of these two interfaces:
|
|
//!
|
|
//! ```rust,no_run,standalone_crate
|
|
//! # #[tokio::main]
|
|
//! # async fn main() -> Result<(), Box<dyn std::error::Error>> {
|
|
//! use subxt::client::OnlineClient;
|
|
//! use subxt::config::PolkadotConfig;
|
|
//!
|
|
//! // Create client:
|
|
//! let client = OnlineClient::<PolkadotConfig>::new().await?;
|
|
//!
|
|
//! // Get events from the latest block (use .at() to specify a block hash):
|
|
//! let events = client.blocks().at_latest().await?.events().await?;
|
|
//! // We can use this shorthand too:
|
|
//! let events = client.events().at_latest().await?;
|
|
//! # Ok(())
|
|
//! # }
|
|
//! ```
|
|
//!
|
|
//! Once we've loaded our events, we can iterate all events or search for specific events via
|
|
//! methods like [`crate::events::Events::iter()`] and [`crate::events::Events::find()`]. See
|
|
//! [`crate::events::Events`] and [`crate::events::EventDetails`] for more information.
|
|
//!
|
|
//! ## Example
|
|
//!
|
|
//! Here's an example which puts this all together:
|
|
//!
|
|
//! ```rust,ignore
|
|
#![doc = include_str!("../../../examples/events.rs")]
|
|
//! ```
|
|
//!
|