Ash.count in code interface?

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1

Hey gang, looking for the most idiomatic place to put a function that essentially calls Ash.count/2. It feels like there is an obvious way to define this as part of the code interface, but I don’t see it.

For example, if the resource is Item, something like this:

  resources do
    resource MyApp.SomeDomain.Item do
      ...
      # what I am thinking
      define :items_count, action: :read, query: ...
    end
  end

Or just add a normal function in the domain module?

  resources do
    resource MyApp.SomeDomain.Item do
      ...
    end
  end

  # keep it simple
  def items_count do
    Ash.count(MyApp.SomeDomain.Item)
  end

Thanks all

2

So, there are two things to note here:

Functions are cool

Sometimes it can feel like it’s going against the grain in Ash to define functions. Ultimately it’s not :smiley: Your domain is like your context and it’s fine to define functions in it.

So your #keep it simple comment is on point. If thats all it is then thats all it is :smiley:

Generic Actions are an option

There are use cases for generic actions, which are essentially just typed functions that can provide some benefits:

  1. You can write policies around them
  2. They emit traces into analytics
  3. They validate the types of their inputs

So what that looks like is an action on items like this:

action :item_count, :integer do
  run fn _input, _context -> 
    Ash.count(__MODULE__)
  end
end

And then in your domain:

  resources do
    resource MyApp.SomeDomain.Item do
      define :item_count
    end
  end

At the end of the day, if you don’t need any of the benefits of a generic action, go with #1, otherwise #2.

3 Likes
3

I think that’s exactly what I was looking for. Makes sense, thanks for the clarity.

1 Like