I am using substrate-contracts-node. I've uploaded and instantiated the smart contract. I would like to interact and query the function using py-substrate-interface. However, I ran into an error while following this guide - https://polkascan.github.io/py-substrate-interface/usage/ink-contract-interfacing/#deploy-a-contract

This is my code:

contract_address = '5Guya7pPPJC5bDy6yjpLZQ6Tw4D3pow8pvebEnFxMsyd5d31'
# Create contract instance from deterministic address
contract = ContractInstance.create_from_address(
    metadata_file=os.path.join(os.path.dirname(__file__), '/home/<name>/TODO-List/todo_list/target/ink', 'metadata.json'),

result = contract.read(keypair, 'get_owner')

This is the error message:

Traceback (most recent call last):
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/scalecodec/types.py", line 1232, in process
    enum_type_mapping = self.type_mapping[self.index]
IndexError: list index out of range

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "main.py", line 24, in <module>
    result = contract.read(keypair, 'get_owner')
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/substrateinterface/contracts.py", line 766, in read
    call_result = self.substrate.runtime_call("ContractsApi", "call", {
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/substrateinterface/base.py", line 1258, in runtime_call
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/scalecodec/base.py", line 874, in decode
    self.value_serialized = self.process()
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/scalecodec/types.py", line 1755, in process
    value = super().process()
  File "/home/<name>/TODO-List/myenv/lib/python3.8/site-packages/scalecodec/types.py", line 1245, in process
    raise ValueError("Index '{}' not present in Enum type mapping".format(self.index))
ValueError: Index '202' not present in Enum type mapping

Smart contract was tested and built without any issue. get_owner() is a simple function in a smart contract that returns an AccountId.


1 Answer 1



  • What version of substrate-interface are you using?
  • Where is the source code of the todo_list smart contract?

Perhaps you could try using a more recent version of both substrate-interface, and python even though you're using version 3.8 and the repo indicates that it's supported.

I understand that you used substrate-contracts-node to deploy the smart contract to a local testnet on your machine at '5Guya7pPPJC5bDy6yjpLZQ6Tw4D3pow8pvebEnFxMsyd5d31'.

I just tried to replicate your issue using the following recent versions:

  • substrate-interface 1.7.0
  • python 3.11
  • flipper example smart contract that I generated using cargo contract 2.2.1

I followed the same guide as you with the steps here.

First I got an error TypeError: ContractCode.deploy() got an unexpected keyword argument 'endowment'.

So I reviewed the substrate-interface 1.7.0 source code that I found at https://github.com/polkascan/py-substrate-interface/blob/v1.7.0/substrateinterface/contracts.py to discover that argument has been removed, so the guide appears to be outdated.

Then I got the following error:

Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/scalecodec/types.py", line 592, in process_encode
    value = {key: value[idx] for idx, (key, _) in enumerate(self.type_mapping)}
  File "/usr/local/lib/python3.11/site-packages/scalecodec/types.py", line 592, in <dictcomp>
    value = {key: value[idx] for idx, (key, _) in enumerate(self.type_mapping)}
IndexError: tuple index out of range

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/app/docker/ink-python/src/app.py", line 52, in <module>
    contract = code.deploy(
  File "/usr/local/lib/python3.11/site-packages/substrateinterface/contracts.py", line 658, in deploy
    call = self.substrate.compose_call(
  File "/usr/local/lib/python3.11/site-packages/scalecodec/types.py", line 594, in process_encode
    raise ValueError("Not enough items in tuple to match type_mapping")
ValueError: Not enough items in tuple to match type_mapping

That was again caused because that guide is outdated since they are using an argument value of gas_limit=1000000000000, instead of a dictionary tuple like gas_limit={'ref_time': 25990000000, 'proof_size': 11990},. So after I changed that it fully deployed the smart contract to Contracts Rococo successfully and returned Current value of "get": {'Ok': True}.

This is the code I used. Note: I just made up any value for the ref_time and proof_size that worked without causing an OutOfGas error.

import os
from dotenv import load_dotenv
from substrateinterface import SubstrateInterface, Keypair, KeypairType, ContractCode, ContractInstance


MNEMONIC = os.getenv('MNEMONIC')

provider_rococo = "wss://rococo-contracts-rpc.polkadot.io"
substrate = SubstrateInterface(
keypair_ls = Keypair.create_from_mnemonic(

# deploy contract
up = [os.pardir]*3
go_up = os.path.join(*up)
code = ContractCode.create_from_contract_files(
    metadata_file=os.path.join(os.path.dirname(__file__), go_up, 'target', 'ink', 'flipper', 'flipper.json'),
    wasm_file=os.path.join(os.path.dirname(__file__), go_up, 'target', 'ink', 'flipper', 'flipper.wasm'),
contract = code.deploy(
    args={'init_value': True},
    gas_limit={'ref_time': 25990000000, 'proof_size': 11990},
print(f'✅ Deployed @ {contract.contract_address}')

# create contract instance from deterministic address
contract_existing = ContractInstance.create_from_address(
    metadata_file=os.path.join(os.path.dirname(__file__), go_up, 'target', 'ink', 'flipper', 'flipper.json'),
print(f'Existing deployed @ {contract_existing.contract_address}')

# read data from contract
result = contract_existing.read(keypair_ls, 'get')
print('Current value of "get":', result.contract_result_data)

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