How to solve the issue"Element "asset_id" of struct is missing in given value" when I send a token transaction

Question

I send the transaction using the substrate interface.

I get the key pair and call:

call_module = "Assets"
call_function = 'transfer'
call_params = {
    "id": asset_id,
    "target": target,
    'amount': amount,
 }

Then, I sign the transaction using substrate.create_signed_extrinsic, but I get an error:

raise ValueError('Element "{}" of struct is missing in given value'.format(key))

ValueError: Element "asset_id" of struct is missing in given value

Answer 1

Are you sure you have the latest version of packages substrate-interface==1.2.2 and scalecodec==1.0.34?

Because I can remember older versions of scalecodec don't have the 'signed_extensions' support that is included in the metadata and Statemine has the ChargeAssetTxPayment extension.

I was successfully able to transfer an asset on Statemine with the following code:

keypair = Keypair.create_from_mnemonic(mnemonic)
substrate = SubstrateInterface(
    url="wss://statemine-rpc.polkadot.io"
)

call = substrate.compose_call(
    call_module="Assets",
    call_function="transfer",
    call_params={'id': asset_id, 'target': account_id, 'amount': amount}
)

extrinsic = substrate.create_signed_extrinsic(call=call, keypair=keypair)

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