substrate-interface

import os from substrateinterface import SubstrateInterface # Connect to a public Polkadot node by default # Override with environment variable SUBSTRATE_NODE_URL if needed node_url = os.environ.get('SUBSTRATE_NODE_URL', 'wss://rpc.polkadot.io') try: substrate = SubstrateInterface( url=node_url ) print(f"Connected to chain: {substrate.chain}") print(f"Node name: {substrate.node_name}") print(f"Node version: {substrate.node_version}") print(f"Current block number: {substrate.chain_head}") # Example: Query account balance for a well-known test address (Alice) # Override with environment variable POLKADOT_ALICE_ADDRESS if needed alice_address = os.environ.get('POLKADOT_ALICE_ADDRESS', '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY') # The 'System' module and 'Account' storage map are standard across Substrate chains. # The exact structure of the account info might vary slightly by chain/runtime version. result = substrate.query( module='System', function='Account', params=[alice_address] ) # Accessing the free balance, typically found under 'data' and 'free'. # Assuming 10 decimal places for Polkadot for display purposes. # The '.value' attribute extracts the raw integer. free_balance = result['data']['free'].value print(f"Balance for {alice_address}: {free_balance / 10**10} DOT") except ConnectionRefusedError: print(f"Error: Connection refused. Is the node running or accessible at {node_url}?") except Exception as e: print(f"An unexpected error occurred: {e}") finally: if 'substrate' in locals() and substrate.is_connected: substrate.close()