subxt for Pontem
A library to submit extrinsics to a substrate node via RPC.
⚠️ Health Warning ⚠️ considered alpha after recent changes, API still subject to change
See paritytech#309 for an overview of outstanding issues.
Usage
Downloading metadata from a Substrate node
Use the subxt-cli
tool to download the metadata for your target runtime from a node.
- Install:
cargo install subxt-cli
- Save the encoded metadata to a file:
subxt metadata -f bytes > metadata.scale
This defaults to querying the metadata of a locally running node on the default http://localhost:9933/
. If querying
a different node then the metadata
command accepts a --url
argument.
Generating the runtime API from the downloaded metadata
Declare a module and decorate it with the subxt
attribute which points at the downloaded metadata for the
target runtime:
#[subxt::subxt(runtime_metadata_path = "metadata.scale")]
pub mod node_runtime { }
Important: runtime_metadata_path
resolves to a path relative to the directory where your crate's Cargo.toml
resides (CARGO_MANIFEST_DIR
), not relative to the source file.
Initializing the API client
API is still a work in progress. See examples for the current usage.
Querying Storage
API is still a work in progress. See tests for the current usage.
Submitting Extrinsics
API is still a work in progress. See examples for the current usage.
Integration Testing
Most tests require a running substrate node to communicate with. This is done by spawning an instance of the
substrate node per test. It requires an executable binary substrate
at polkadot-v0.9.10
on your path.
This can be installed from source via cargo:
cargo install --git https://github.com/paritytech/substrate node-cli --tag=polkadot-v0.9.10 --force
Alternatives
substrate-api-client provides similar functionality.