substrate-interface

Python Substrate Interface

Description

This library specializes in interfacing with a Substrate node; querying storage, composing extrinsics, SCALE encoding/decoding and providing additional convenience methods to deal with the features and metadata of the Substrate runtime.

Documentation

• Library documentation
• Metadata documentation for Polkadot and Kusama ecosystem runtimes

Installation

pip install substrate-interface

Initialization

Using embedded light client

substrate = SubstrateInterface(chainspec="polkadot_asset_hub", relay_chainspecs=["polkadot"])

Using node RPC endpoint

substrate = SubstrateInterface(url="ws://127.0.0.1:9944")

After connecting certain properties like ss58_format will be determined automatically by querying the RPC node. At the moment this will work for most MetadataV14 and above runtimes like Polkadot, Kusama, Acala, Moonbeam. For older or runtimes under development the ss58_format (default 42) and other properties should be set manually.

Quick usage

Balance information of an account

result = substrate.query('System', 'Account', ['F4xQKRUagnSGjFqafyhajLs94e7Vvzvr8ebwYJceKpr8R7T'])
print(result.value['data']['free']) # 635278638077956496

Create balance transfer extrinsic

call = substrate.compose_call(
    call_module='Balances',
    call_function='transfer',
    call_params={
        'dest': '5E9oDs9PjpsBbxXxRE9uMaZZhnBAV38n2ouLB28oecBDdeQo',
        'value': 1 * 10**12
    }
)

keypair = Keypair.create_from_uri('//Alice')
extrinsic = substrate.create_signed_extrinsic(call=call, keypair=keypair)

receipt = substrate.submit_extrinsic(extrinsic, wait_for_inclusion=True)

print(f"Extrinsic '{receipt.extrinsic_hash}' sent and included in block '{receipt.block_hash}'")

Contact and Support

For questions, please see the Substrate StackExchange or Github Discussions.

License

https://github.com/JAMdotTech/py-polkadot-sdk/blob/master/LICENSE