dewetblomerus

Code interface for resource owned by User

I have a resource that belongs_to a User.

When I create one with my code_interface I pass in a user_id.

I want to start creating code interfaces for querying the resources belonging to that user, I can again pass in user_id.

However, when I look at the code generated by ash_phoenix.gen.live I see this beauty:

  AshPhoenix.Form.for_create(Red.Api.Attempt, :create,
  api: Red.Api,
  as: "attempt",
  actor: socket.assigns.current_user
)

Instead of passing in the user_id, I just pass in the user as an actor.

What is the convention here? (Please don’t tell me to do whatever I feel like, I feel like learning the conventional/idiomatic Ash way of doing this).

If the convention is to pass in an actor in the code interface. Please share a link to an example if possible.

8 comments

/ash #ash-authentication #ash-code-interface

1 900 8

2023-10-17 14:54:57 UTC

Marked As Solved

zachdaniel

Creator of Ash

right, so now what you need to do is use the current user in the action to map it to the user relationship in some way.

The long way:

change fn changeset, context -> 
  Ash.Changeset.change_attribute(changeset, :user_id, context.actor.id)
end

The built in way:

# relate the actor to the `:user` relationship of this record.
change relate_actor(:user)

Post #6

Also Liked

zachdaniel

Creator of Ash

The general pattern is to first ask yourself what kind of action you are writing. If you are writing the sort of action that is “contextual to the actor”, i.e. “create_my_thing”. vs “create_thing_for_user”. They are subtly different, and in many cases you may have both. I.e some admin version of an action that allows supplying any user.

Generally speaking, your best bet is to start by preferring to use the actor, and if later you determine that you want someone to be able to take that action “on behalf of” another user, you can either add another version of the action, or modify the internals of the action to expect an actor or a supplied user_id (for example).

All code interface functions accept an actor option, i.e YourResource.create!(...., actor: actor).

So to sum up, prefer to write “actor-specific” actions (as you described), as they are easier to reason about.

Post #3

dewetblomerus

Oh gotcha! Thanks for clarifying. I did that and it works.

Here’s my whole Resource now, just in case someone else is wanting a complete example:

defmodule Red.Practice.Card do
  use Ash.Resource,
    data_layer: AshPostgres.DataLayer

  actions do
    defaults [:read, :update]

    create :create do
      change relate_actor(:user)
    end
  end

  code_interface do
    define_for Red.Practice

    define :create, action: :create
  end

  attributes do
    integer_primary_key :id

    attribute :word, :string, allow_nil?: false
    attribute :tried_at, :utc_datetime, allow_nil?: true
    attribute :retry_at, :utc_datetime, allow_nil?: true
    attribute :correct_streak, :integer, allow_nil?: false, default: 0

    create_timestamp :created_at
    create_timestamp :updated_at
  end

  identities do
    identity :unique_word, [:word, :user_id]
  end

  relationships do
    belongs_to :user, Red.Accounts.User,
      attribute_writable?: true,
      attribute_type: :integer,
      allow_nil?: false
  end

  postgres do
    table "cards"
    repo Red.Repo
  end
end

I can’t guarantee that this file will keep living here, but if someone wants to see the up-to-date changes: red/lib/red/practice/resources/card.ex at main · dewetblomerus/red · GitHub

Post #9

dewetblomerus

That is exactly what I needed Thank you, Zack.

Post #4

Last Post!

dewetblomerus

Oh gotcha! Thanks for clarifying. I did that and it works.

Here’s my whole Resource now, just in case someone else is wanting a complete example:

defmodule Red.Practice.Card do
  use Ash.Resource,
    data_layer: AshPostgres.DataLayer

  actions do
    defaults [:read, :update]

    create :create do
      change relate_actor(:user)
    end
  end

  code_interface do
    define_for Red.Practice

    define :create, action: :create
  end

  attributes do
    integer_primary_key :id

    attribute :word, :string, allow_nil?: false
    attribute :tried_at, :utc_datetime, allow_nil?: true
    attribute :retry_at, :utc_datetime, allow_nil?: true
    attribute :correct_streak, :integer, allow_nil?: false, default: 0

    create_timestamp :created_at
    create_timestamp :updated_at
  end

  identities do
    identity :unique_word, [:word, :user_id]
  end

  relationships do
    belongs_to :user, Red.Accounts.User,
      attribute_writable?: true,
      attribute_type: :integer,
      allow_nil?: false
  end

  postgres do
    table "cards"
    repo Red.Repo
  end
end

I can’t guarantee that this file will keep living here, but if someone wants to see the up-to-date changes: red/lib/red/practice/resources/card.ex at main · dewetblomerus/red · GitHub

Post #9