With subxt how can I subscribe to watch extrinsics?

Question

There's some great examples of how to use subxt to listen to all events.

Polkadot-js events screen seem to show events grouped by the extrinsic that created them. Can I do the same in rust?

(if not subxt is there an alternative way?)

Answer 1

The logic in subxt will map through in a similar way.

The EventRecord struct contains a Phase enum where ApplyExtrinsic(u32) refers to the index of the extrinsic in the block.

So the way to map it is -

1. If phase is not ApplyExtrinsic, it doesn't map to a transaction, e.g. it is a system event
2. If the phase is ApplyExtrinsic, get the index from this value
3. Map the extracted index to the extrinsic, as found in the block