feat: subscription dsl

[barnabasJ]

Contributor checklist

• Bug fixes include regression tests
• Features include unit/acceptance tests

[barnabasJ]

@zachdaniel I tried to create a test case for the current behaviour before trying to move the code into the dsl but I got a bit stuck.

I copied stuff from https://github.com/absinthe-graphql/absinthe/blob/master/test/absinthe/execution/subscription_test.exs and https://github.com/ash-project/ash/blob/main/test/notifier/pubsub_test.exs but I can't see any messages. I think I'm missing something, Maybe you can give me a hint to get unstuck.

Thanks

[zachdaniel]

Will take a look tomorrow 👍

[zachdaniel]

The issue doesn't jump out to me immediately...the first step might be to add a custom notifier and make sure notifications are going out at all.

[barnabasJ]

build_read_one_query
|> Ash.can(....)
|> case do
  {true, query} ->
     if query.authorize_results == [] && we_can_tell_the_record_matches(record, query.filter) do
      just load any necessary data on the record we got
    else
      do a read one w/ the load
    end
end

Can you explain what query.authorize_results == [] means? Because I'm not sure what is stored there and it makes me unsure of what to do if Ash.can only returns {:ok, true}.

for we_can_tell_the_record_matches can I use Ash.Filter.Runtime.filter_matches(query.domain, [data], query.filter)?

[zachdaniel]

query.authorize_results is a set of hooks that authorizers can add that run after the query is run. If you just get back {:ok, true} then that can be treated as the same as query.authorize_results == [] (it means there is nothing else to do). Although IIRC if you pass alter_source?: true you're guaranteed to get back the query.

For evaluating the filter against the record, I'd use something like Ash.Expr.eval(expression, resource: resource, unknown_on_unknown_refs?: true). That will do a sort of "shallow check" without running any queries or anything. If that returns :unknown then you have to run the query. Otherwise you know what the result will be.

[zachdaniel]

🚀 lets gooooooooo.

Awesome work!

[zachdaniel]

Feel free to merge at your convenience :)

[barnabasJ]

@zachdaniel accepting your suggestion dismissed your approval, now merging is blocked again 😅