Use read action in LV's update_many function

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1

I have a resource called Entity which has a one to many relationship with a resource called SkipTrace.

I have an action in the SkipTrace that will return all skip traces for a specific entity id.

In my LV page, I have a list of entities and I want to load their skip traces using the LV’s update_many function. In other words, I want to call my action from the SkipTrace once but instead of sending the entity id as argument, I want to send a list of entities ids, return all of them and group them by the entity id.

Can I do that by reusing my already existing read action from the SkipTrace resource? What is the most “idiomatic” way to do that in Ash?

2

Probably the easiest way is to load the SkipTraces when you’re loading the Entity (ies).

e.g.

entities = Entity.read!(load: [:skiptraces])

They are then available from each Entity, e.g.

Enum.map(entities, fn entity ->
   IO.inspect(entity.skiptraces)
end

You can then access them as needed from your update_many

1 Like
3

If you have an action that takes an id as an argument and applies a filter, then there isn’t a way to use it as you’ve described, as it will always apply the filter for a single item.

If you have the actual Entity records then you can do it very simply, just Ash.load(entities, :skip_traces). If you only have the ids you can do something similar ids |> Enum.map(&%Entity{id: &1}) |> Ash.load(:skip_traces).

You could also make a separate action that accepts an ids argument instead of just id, and does a filter expr(id in ^ids)

read :action_name do
  argument :id, :uuid
  argument :ids, {:array, :uuid}
  
  filter expr(
    cond do
      not is_nil(^arg(:ids)) -> id in ^arg(:ids)
      not is_nil(^arg(:id)) -> id == ^arg(:id)
      true -> true
    end
  )
end

I wrote all of the above and then got majorly distracted, since then @mindok has pointed out a true thing which is that the simplest way is always going to be loading on records that you already have :slight_smile:

2 Likes
4

Thanks! I don’t have the entity available in the component, only its id, so doing the ids |> Enum.map(&%Entity{id: &1}) |> Ash.load(:skip_traces) trick is what I needed!