Relation#subscribe is not consistent

[hecrj]

Events received during a subscription are dispatched directly to the given block, thus they don't go through the relation pipeline. That means that mappers don't affect the received events:

rom.relation(:tasks).as(:entity).subscribe do |event|
  # event is not an entity here...
end

Is there an easy way to fix this?

[solnic]

If you push this logic up to relation from dataset it should work.

[hecrj]

But how do I pass the event through the mapper, if there is one? Right now I'm just yielding the event as it arrives (asynchronously), I don't see how moving the logic up to relation would help :/ Is there some way to pass the data through the Composite relation from there?

[solnic]

Ah, right, that's tricky. You'd have to extend Relation::Composite too. I don't think it's a good idea.

Maybe it would be a better idea to have that interface available via repository? It looks like on_event yields individual objects in a callback-style so that's not gonna work so well with ROM's data pipeline.

[hecrj]

Maybe something like subscribe.each could work? subscribe could alter the behavior of the each method somehow... I'll think about it.