Snapshot Event Handler State #588

marpo60 · 2021-11-09T14:52:05Z

marpo60
Nov 9, 2021

Event Handler State is provided in the init/1 callback and can be updated in each handle/2
https://hexdocs.pm/commanded/1.3.0/Commanded.Event.Handler.html#module-event-handler-state

This is pretty handy, but at this moment the state is ephemeral, which means that on server restart, there is a need to reconstruct the state.

It would be awesome if the EventHandler state could be persisted in the same fashion as the Process Manager state.

Lines 82 to 84 in 1c8af07

    
           def init(%State{} = state) do 
        
             {:ok, state, {:continue, :fetch_state}} 
        
           end

Line 243 in 1c8af07

:ok = persist_state(event_number, state)

If there is value in doing this I can start implementing this.

slashdotdash · 2021-11-10T08:44:16Z

Yes, I agree this would be a useful opt-in feature for event handlers. A pull request would be very welcome, thanks!

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