Convert transaction pool entry into Call

Question

How can I match on runtime Calls from my outer node? I essentially want to "trigger" the node once a type of extrinsic is submitted. It seems like I don't have an option to emit any kind of observable from WASM, so I'm attempting to watch the import_notification_stream from the transaction pool. This works, but now I'm struggling to unwrap the underlying call in the transaction.

let mut commands_stream = Box::pin(cloned_pool.import_notification_stream());
        while let Some(tx_hash) = commands_stream.next().await {
            log::info!("got hash for tx: {:?}", tx_hash);
            if let Some(tx) = cloned_pool.ready_transaction(&tx_hash) {
                let uxt: Block::Extrinsic = tx.data().clone();
                ... how to now convert to call and match

Answer 1

There are two ways to do this, the first one is by having a Runtime api that automtically do all the deserailisation for you than match the call like this, for example if i want to check whether an extrinsic is of a specific type i would have something like this:

    fn verify_extrinsic(extrinsic: <Block as BlockT>::Extrinsic)-> bool
        {
                if let Call::MyPallet(pallet_my_pallet::Call::<Runtime>::test_call{param1:_,param2:_}) = &extrinsic.function
                {
                    // or do some other stuff
                    false
                }else
                {
                    true
                }
        }
    }

now we update your code:

 let uxt: Block::Extrinsic = tx.data().clone();
let result = client.runtime_api().verify_extrinsic(&best_block_id, uxt.clone())
// do something with the result
 

the other way is to do manual scale decoding of the extrinsic which i think is a hustle.