Invoking An Auth Contract with Transaction Invoker Authorization using Soroban Python SDK

In my previous post, I showed you how to deploy and invoke an auth contract with stellar account authorization using Soroban Python SDK. In this post, we'll use Soroban Python SDK to invoke an auth contract with transaction invoker authorization. I will use auth contract that already deployed in previous post, so i dont need to deploy it again.

Preparation

First, create a Futurenet account, this account will be used to deploy the auth contract and invoke the contract using Soroban Python SDK. Create account at Stellar Laboratory and make sure to fund them. The account that i will be using :

Public Key  GATQFKA7BV7LYYE6UJ2LRL56W3BZRRSWTINA6TG2EM5CCDORFIERAKWV
Secret Key  SCHKLGAGY7QGWUKUFDGHEQMSCPFZNMLEHQE6Y6WPGYGHQIM23T3NJE3C

The files that we're gonna use :

soroban_auth_with_transaction_invoke.py - The python script to invoke the auth contract with transaction invoker authorization.

Invoking the Contract

To invoke the auth contract, open the soroban_auth_with_transaction_invoke.py file and adjust the following parameters:

contract_id = "af0aadafacc6bcb73b6ec9aeee03350ca0c6a3430e099d4b5dd371c6e07cc214"
tx_submitter_kp = Keypair.from_secret(
    "SCHKLGAGY7QGWUKUFDGHEQMSCPFZNMLEHQE6Y6WPGYGHQIM23T3NJE3C"
)

tx_submitter_kp: the secret key of the account you'll use to submit the transaction and invoke the function.
contract_id: the contract ID of the auth contract you want to invoke. Replace the value with the contract ID you received from deploying contract before.

Save the soroban_auth_with_transaction_invoke.py file with your changes.

Before running the script, i want to explain this specific codes :

func_name = "increment"
args = [Address(tx_submitter_kp.public_key), Uint32(10)]

invocation = AuthorizedInvocation(
    contract_id=contract_id,
    function_name=func_name,
    args=args,
    sub_invocations=[],
)

contract_auth = ContractAuth(
    address=None,
    nonce=None,
    root_invocation=invocation,
)

source = soroban_server.load_account(tx_submitter_kp.public_key)
tx = (
    TransactionBuilder(source, network_passphrase)
    .add_time_bounds(0, 0)
    .append_invoke_contract_function_op(
        contract_id=contract_id,
        function_name=func_name,
        parameters=args,
        auth=[contract_auth],
    )
    .build()
)

From the script above the function of the contract that we're going to invoke is increment function and It sets address and nonce to None in the ContractAuth. This is for transaction invoker authorization, where the transaction sender is the authorizer.

Now we will run the script using this command :

python soroban_auth_with_transaction_invoke.py

We will get result:

transaction result: <SCVal [type=1, u32=<Uint32 [uint32=10]>]>

Closing

In this blog post, we have gone over the steps to Deploy and Invoke Auth Contract with Transaction Invoker Authorization using Soroban Python SDK. From the script you will get an insight how basic Transaction Invoker Authorization implemented in Soroban Python SDK.