What is the best practice for `Ash.can?/3`

nallwhy · July 26, 2024, 4:04pm

Here’s the my example.

gist.github.com

https://gist.github.com/nallwhy/77f6fee12d919c2513f0ada2487d6e22

server.ex

Mix.install(
  [
    {:plug_cowboy, "~> 2.7"},
    {:jason, "~> 1.0"},
    {:phoenix, "~> 1.7.0"},
    {:phoenix_live_view, "~> 0.20.0"},
    {:ash, "3.2.6"},
    {:ash_phoenix, "2.0.4"},
    {:ash_state_machine, "0.2.5"},
    {:simple_sat, "~> 0.1"}

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I’m working with structure where a Room has_one Contract, and I want to enforce that a contract can only be created when the room is unsold. However, when using Ash.can?({Contract, :create}, actor), I can’t access the parent room’s state. So, I thought it would be necessary to verify the policy through Ash.can?({Room, :contract}, actor). For this reason, I’ve adjusted the Room’s contract action to take :contract_params in a map. This adjustment has led me to wrap my form inputs with inputs_for.

I’m not entirely happy with this solution and am unsure if there’s a better method. I would like to hear your thoughts or any alternatives.

zachdaniel · July 29, 2024, 1:18pm

It’s an interesting question. This works for updates because you have the Contract. You could try doing something like Ash.can?({%Contract{room: %Room{}}, :create}), but I’m not sure if the can? code will check for that on create.

nallwhy · July 30, 2024, 1:19am

Thank you for your response. I tried to apply the method you mentioned, I haven’t been able to apply it yet due to my limited understanding of Ash.can?.