mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-06-19 21:41:02 +00:00
pezkuwichain
99e4ee3ab8
- Renamed all subxt crates to pezkuwi-subxt - Updated internal references - Configured for Pezkuwi ecosystem
55 lines
2.0 KiB
Rust
55 lines
2.0 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.
|
|
|
|
//! # Constants
|
|
//!
|
|
//! There are various constants stored in a node; the types and values of these are defined in a
|
|
//! runtime, and can only change when the runtime is updated. Much like [`super::storage`], we can
|
|
//! query these using Subxt by taking the following steps:
|
|
//!
|
|
//! 1. [Constructing a constant query](#constructing-a-query).
|
|
//! 2. [Submitting the query to get back the associated value](#submitting-it).
|
|
//!
|
|
//! ## Constructing a constant query
|
|
//!
|
|
//! We can use the statically generated interface to build constant queries:
|
|
//!
|
|
//! ```rust,no_run,standalone_crate
|
|
//! #[pezkuwi_subxt::subxt(runtime_metadata_path = "../artifacts/polkadot_metadata_full.scale")]
|
|
//! pub mod polkadot {}
|
|
//!
|
|
//! let constant_query = polkadot::constants().system().block_length();
|
|
//! ```
|
|
//!
|
|
//! Alternately, we can dynamically construct a constant query. A dynamic query needs the return
|
|
//! type to be specified, where we can use [`crate::dynamic::Value`] if unsure:
|
|
//!
|
|
//! ```rust,no_run,standalone_crate
|
|
//! use pezkuwi_subxt::dynamic::Value;
|
|
//!
|
|
//! let storage_query = pezkuwi_subxt::dynamic::constant::<Value>("System", "BlockLength");
|
|
//! ```
|
|
//!
|
|
//! ## Submitting it
|
|
//!
|
|
//! Call [`crate::constants::ConstantsClient::at()`] to return and decode the constant into the
|
|
//! type given by the address, or [`crate::constants::ConstantsClient::bytes_at()`] to return the
|
|
//! raw bytes for some constant.
|
|
//!
|
|
//! Constant values are pulled directly out of the node metadata which Subxt has
|
|
//! already acquired, and so this function requires no network access and is available from a
|
|
//! [`crate::OfflineClient`].
|
|
//!
|
|
//! Here's an example using a static query:
|
|
//!
|
|
//! ```rust,ignore
|
|
#![doc = include_str!("../../../examples/constants_static.rs")]
|
|
//! ```
|
|
//!
|
|
//! And here's one using a dynamic query:
|
|
//! ```rust,ignore
|
|
#![doc = include_str!("../../../examples/constants_dynamic.rs")]
|
|
//! ```
|
|
//!
|