Crate subxt_codegen

source ·
Expand description

Library to generate an API for a Substrate runtime from its metadata.

Generated Structure

The API generator logic:

  • At the root there is the item_mod provided (ie pub mod api {})
  • Pallets are represented by a child module (ie pub mod PalletName {}) of the root
  • Each pallet exposes as child modules (if applicable):
    • Calls (pub mod calls {})
    • Events (pub mod events {})
    • Storage (pub mod storage {})
    • Constants (pub mod constants {})

Example

use std::fs;
use codec::Decode;
use frame_metadata::RuntimeMetadataPrefixed;
use subxt_codegen::{CratePath, DerivesRegistry, TypeSubstitutes};

let encoded = fs::read("../artifacts/polkadot_metadata.scale").unwrap();

// Runtime metadata obtained from a node.
let metadata = <RuntimeMetadataPrefixed as Decode>::decode(&mut &*encoded).unwrap();
// Module under which the API is generated.
let item_mod = syn::parse_quote!(
    pub mod api {}
);
// Default module derivatives.
let mut derives = DerivesRegistry::new(&CratePath::default());
// Default type substitutes.
let substs = TypeSubstitutes::new(&CratePath::default());
// Generate the Runtime API.
let generator = subxt_codegen::RuntimeGenerator::new(metadata);
// Include metadata documentation in the Runtime API.
let generate_docs = true;
let runtime_api = generator.generate_runtime(item_mod, derives, substs, CratePath::default(), generate_docs).unwrap();
println!("{}", runtime_api);

Modules

  • utils
    Utilities to help with fetching and decoding metadata.

Structs

  • CratePath
    A newtype wrapper which stores the path to the Subxt crate.
  • Derives
    A struct storing the set of derives and derive attributes that we’ll apply to generated types.
  • DerivesRegistry
    A struct containing the derives that we’ll be applying to types; a combination of some common derives for all types, plus type specific derives.
  • Module
    Represents a Rust mod, containing generated types and child mods.
  • RuntimeGenerator
    Create the API for interacting with a Substrate runtime.
  • TypeGenerator
    Generate a Rust module containing all types defined in the supplied PortableRegistry.
  • TypeSubstitutes
    A map of type substitutes. We match on the paths to generated types in order to figure out when to swap said type with some provided substitute.

Enums

Functions