Feature Request: A query that returns the most recent event for a given filter.

[4c656554]

Thanks to the developers for this great software!

This is a "would be nice to have" feature request to add a flag to the JSON-RPC/GraphQL query input have Geth search for the events in reverse chronological order and only return the most recent log (or the batch from that block).

Unless I'm mistaken, at the moment it is only possible to construct queries that return all of the events for a given filter.

If you have a case where you only want the most recent event, but you don't know when it occurred, you still need to get back all of the events and filter (potentially not ideal on a client machine).

See also:

https://ethereum.stackexchange.com/questions/41976/how-to-get-only-latest-log-from-my-event
https://ethereum.stackexchange.com/questions/8699/how-to-get-only-latest-logged-event-via-web3-api

Thanks,

Lee

[adamschmideg]

A legit feature request. We'd first need a solid test suite for filtering.

[karalabe]

This is not a bad idea, but our log filtering is a bit messy and not properly tested. We'd need to start by writing a very comprehensive test suite to avoid introducing regressions.

[4c656554]

Something along the lines of this? :- https://github.com/ethereum/rpc-tests

My approach would be to:

1. duplicate the unindexedLogs function (as unindexedLogsReverse ) and adjust to iterate from end to head and return when it finds a log.

2. duplicate getFilterLogs (as e.g. getLastFilterLog) to call above function.

3. Add a references to a new API call (e.g. getLastFilterLog ) and link to above, if this is needed.

N.b. If it's not apparent, I haven't yet got a good understanding of the architecture, and am not familiar with Go.

[lhendre]

@karalabe is there an issue or has the test suite been created?