dmitriid Posts - Answer Overflow

dmitriid

•Created by dmitriid on 4/10/2023 in #support

protocol Enumerable not implemented for #Ash.Changeset

I apologize if I abuse the support channel, please tell me if I should take this to #general or #archive-debugging I've ran into this issue on two different resources, and I'll detail both below. The tl;dr is: I define a code_interface for a resource, but when I call the function it fails with protocol Enumerable not implemented for #Ash.Changeset<action_type: :create... at (ash 2.6.27) lib/ash/changeset/changeset.ex:998: Ash.Changeset.cast_params/3 Resource the first I want to generate an "external id" on creation, so I expose a new acton via code_interface.

defmodule Telepai.App.Session do
  attributes do
    integer_primary_key(:id)
    attribute :external_id, :string
    attribute :settings, :string
  end

  actions do
    defaults([:create, :read, :update, :destroy])

    create :new do
      accept([:settings])

      change(fn changeset, _ ->
        now = NaiveDateTime.utc_now() |> NaiveDateTime.to_string()
        external_id = now |> HumanReadableIdentifierGenerator.fetch_human_readable_id!()

        changeset |> Ash.Changeset.change_attribute(:external_id, external_id)
      end)
    end
  end

  code_interface do
    define_for(__MODULE__)
    define(:new)

    # Note: if I don't define :create, compiler complains that 
    # `create/2` and `create!/2` are private or not defined
    define(:create)
  end
end

defmodule Telepai.App.Session do
  attributes do
    integer_primary_key(:id)
    attribute :external_id, :string
    attribute :settings, :string
  end

  actions do
    defaults([:create, :read, :update, :destroy])

    create :new do
      accept([:settings])

      change(fn changeset, _ ->
        now = NaiveDateTime.utc_now() |> NaiveDateTime.to_string()
        external_id = now |> HumanReadableIdentifierGenerator.fetch_human_readable_id!()

        changeset |> Ash.Changeset.change_attribute(:external_id, external_id)
      end)
    end
  end

  code_interface do
    define_for(__MODULE__)
    define(:new)

    # Note: if I don't define :create, compiler complains that 
    # `create/2` and `create!/2` are private or not defined
    define(:create)
  end
end

Then calling it:

> Telepai.App.Session.new!(%{settings: "aaa"})
protocol Enumerable not implemented for #Ash.Changeset<action_type: :create, action: :new, attributes: %{external_id: "pingo-frangimini-51", settings: "aaa"}, relationships: %{}...
...
    (ash 2.6.27) lib/ash/changeset/changeset.ex:998: Ash.Changeset.cast_params/3
    (ash 2.6.27) lib/ash/changeset/changeset.ex:747: Ash.Changeset.do_for_action/4
    (telepai 0.1.0) lib/ash/code_interface.ex:533: Telepai.App.Session.create!/2

> Telepai.App.Session.new!(%{settings: "aaa"})
protocol Enumerable not implemented for #Ash.Changeset<action_type: :create, action: :new, attributes: %{external_id: "pingo-frangimini-51", settings: "aaa"}, relationships: %{}...
...
    (ash 2.6.27) lib/ash/changeset/changeset.ex:998: Ash.Changeset.cast_params/3
    (ash 2.6.27) lib/ash/changeset/changeset.ex:747: Ash.Changeset.do_for_action/4
    (telepai 0.1.0) lib/ash/code_interface.ex:533: Telepai.App.Session.create!/2

I'll continue with the second resource in the comments

11 replies

AEAsh Elixir

•Created by dmitriid on 4/7/2023 in #support

Lookups/calcultions based on has_many relationships

I will try to be very precise and concise, so apologies if this comes off rude-ish. - The history table contains a long list of entires that a user enters the application. Imagine like a list of chat entries. - The users can bookmark any number of those history entries - when retrieving a list of entries (e.g., last 40 entries, or all entries in a paged manner) I would like to try and in one go retrieve both the entries and whether they were bookmarked by this particular user A corresponding SQL query would be something like

SELECT history.*, 
       CASE WHEN bookmarks.history_id IS NULL THEN 0 ELSE 1 END AS is_bookmarked
FROM history
LEFT JOIN bookmarks ON history.id = bookmarks.history_id;

SELECT history.*, 
       CASE WHEN bookmarks.history_id IS NULL THEN 0 ELSE 1 END AS is_bookmarked
FROM history
LEFT JOIN bookmarks ON history.id = bookmarks.history_id;

I have it sort of figured out with relationships and calculations, but this seems to load more data than I would actually like. Relevant parts only:

defmodule Telepai.App.History do
  attributes do
    integer_primary_key(:id)
    
    attribute :data, :string do
      allow_nil?(false)
      constraints(trim?: true, max_length: 5000, allow_empty?: false)
    end
  end

  relationships do
    has_many :bookmarks, Telepai.Users.Bookmark do
      api(Telepai.Users)

      # I have played with hardcoded filters, too.
      # But of course I don't want it hardcoded in the end :)
      # filter(expr(user_id == 1))
    end
  end

  calculations do
    # hardcoded again
    calculate(:is_bookmarked, :term, expr(bookmarks.user_id == 1))

    # Or even this, but this needs the hardcoded filter in the relationship
    # calculate(:is_bookmarked, :term, expr(not is_nil(bookmarks)))
  end

end

defmodule Telepai.App.History do
  attributes do
    integer_primary_key(:id)
    
    attribute :data, :string do
      allow_nil?(false)
      constraints(trim?: true, max_length: 5000, allow_empty?: false)
    end
  end

  relationships do
    has_many :bookmarks, Telepai.Users.Bookmark do
      api(Telepai.Users)

      # I have played with hardcoded filters, too.
      # But of course I don't want it hardcoded in the end :)
      # filter(expr(user_id == 1))
    end
  end

  calculations do
    # hardcoded again
    calculate(:is_bookmarked, :term, expr(bookmarks.user_id == 1))

    # Or even this, but this needs the hardcoded filter in the relationship
    # calculate(:is_bookmarked, :term, expr(not is_nil(bookmarks)))
  end

end

And the bookmarks:

defmodule Telepai.Users.Bookmark do
  attributes do
    integer_primary_key(:id)
  end

  relationships do
    belongs_to :user, Telepai.Users.User do
      allow_nil?(false)
    end

    belongs_to :history, Telepai.App.History do
      api(Telepai.App.History)
      allow_nil?(false)
    end
  end
end

defmodule Telepai.Users.Bookmark do
  attributes do
    integer_primary_key(:id)
  end

  relationships do
    belongs_to :user, Telepai.Users.User do
      allow_nil?(false)
    end

    belongs_to :history, Telepai.App.History do
      api(Telepai.App.History)
      allow_nil?(false)
    end
  end
end

Continued below

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