How to create AshPhoenix form with Union field

Hey @brady131313 we’re actually actively working on some issues around union types. Can you try main of ash_phoenix and tell me how it goes?

@zachdaniel using main of ash_phoenix works as expected. I can pass the type of the union using both :_union_type and :tag and it works, thank you.

I’m trying to follow the docs:

defmodule PageBlock do
  use Ash.Type.NewType,
    subtype_of: :union,
    constraints: [
      types: [
        hero_simple: [
          type: HeroSimple,
          tag: :type,
          tag_value: :hero_simple
        ],
        hero_media: [
          type: HeroMedia,
          tag: :type,
          tag_value: :hero_media
        ]
      ]
    ]
end

But trying to use this in a resource like so:

attribute :blocks, {:array, PageBlock}, public?: true

Throws error:

** (RuntimeError) {:array, PageBlock} is not a valid type.

Valid types include any custom types, or the following short codes (alongside the types they map to):

Didn’t want to create a new post as i think it’s part of this. I’m using main branch of ash_phoenix

      {:ash, "~> 3.0"},
      {:ash_postgres, "~> 2.0"},
      {:ash_phoenix, github: "ash-project/ash_phoenix", branch: "main"},
      {:picosat_elixir, "~> 0.2.3"},

I’ll try doing it like brady131313

Ok figured it out,
the

defmodule Octafest.Pages.Block do
  use Ash.Type.NewType,
    subtype_of: :union,
    constraints: [
      types: [
        hero_simple: [
          type: HeroSimple,
          tag: :type,
          tag_value: :hero_simple
        ],
        hero_media: [
          type: HeroMedia,
          tag: :type,
          tag_value: :hero_media
        ]
      ]
    ]
end

has to be in a single file by itself
Same for all the others subtypes

Ok running into an issue:

[debug] HANDLE EVENT "save" in OctafestWeb.PageLive.Show
  Parameters: %{"form" => %{"blocks" => %{"0" => %{"_form_type" => "create", "_persistent_id" => "0", "_touched" => "_form_type,_persistent_id,_touched,_union_type,description,navigation_type,title,type", "_union_type" => "hero_media", "description" => "Some description", "navigation_type" => "simple", "title" => "Some title", "type" => "hero_media"}}}}
[warning] Unhandled error in form submission for Octafest.Pages.Page.update_blocks

This error was unhandled because Ash.Error.Framework.MustBeAtomic does not implement the `AshPhoenix.FormData.Error` protocol.

** (Ash.Error.Framework.MustBeAtomic) Octafest.Pages.Page.update_blocks must be performed atomically, but it could not be

Reason: Unions do not support atomic updates

See https://hexdocs.pm/ash/3.0.0/update-actions.html#atomic-updates for more on atomics.

This is my actions on the page resource:

  actions do
    # Truncated...
    update :update_blocks do
      # accept content as input
      accept [:blocks]
    end

Also is there a way to automatically add a nested ember form:

defmodule Octafest.Pages.Block.HeroMedia do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :title, :string, allow_nil?: false
    attribute :description, :string
    attribute :navigation_type, :string
    attribute :image, Octafest.Pages.Components.Image
    attribute :button, Octafest.Pages.Components.Button
  end

  actions do
    defaults [
      :read,
      :destroy,
      create: [:title, :navigation_type, :description, :image, :button],
      update: [:title, :navigation_type, :description, :image, :button]
    ]
  end
end

Here is my image resource:

defmodule Octafest.Pages.Components.Image do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :url, :string
    attribute :alt, :string
    attribute :image_id, :string, allow_nil?: false
    attribute :modifiers, :map, default: %{}
  end

  actions do
    defaults [
      :read,
      :destroy,
      create: [
        :url,
        :alt,
        :image_id,
        :modifiers
      ],
      update: [
        :url,
        :alt,
        :image_id,
        :modifiers
      ]
    ]
  end
end

HeaderMedia is part of a union type:

defmodule Octafest.Pages.Block do
  use Ash.Type.NewType,
    subtype_of: :union,
    constraints: [
      types: [
        hero_simple: [
          type: Octafest.Pages.Block.HeroSimple,
          tag: :type,
          tag_value: :hero_simple
        ],
        hero_media: [
          type: Octafest.Pages.Block.HeroMedia,
          tag: :type,
          tag_value: :hero_media
        ]
      ]
    ]
end

the union type is used like so in the page resource:

attribute :blocks, {:array, Octafest.Pages.Block}, public?: true

Here’s how i add the block:

  @impl true
  def handle_event("add_block", %{"type" => type}, socket) do
    form =
      socket.assigns.form
      |> AshPhoenix.Form.add_form("form[blocks]",
        params: %{
          "_union_type" => type
        }
      )

    {:noreply, assign(socket, :form, form)}
  end

How would i add the nested embed image form based on type?
something like:

case type do
   :header_media -> # TODO attach the image form from the start.

You should be able to include nested paths when you add a form, i.e "form[foo][bar][baz]", is that what you’re looking for?

Kind of:
The blocks is an array
so when adding a new block how do i know to add a nested array to that specific index?

  def handle_event("add_block", %{"type" => type}, socket) do
    form =
      socket.assigns.form
      |> AshPhoenix.Form.add_form("form[blocks]",
        params: %{
          "_union_type" => type
        }
      )

    form =
      case type do
        "hero_media" ->
          form
          |> AshPhoenix.Form.add_form("form[blocks][SOME_INDEX][image]",
            params: %{
              "alt" => ""
            }
          )

        _ ->
          form
      end

How would i get the SOME_INDEX value?

Ah, I mean, I’d have to understand more about what you are specifically trying to do. Do you want it to be the case that any form that is an image automatically has an alt form? Or do you want the form you just added to have that nested form?

If you need the former, then you’ll have to look at the form.forms object yourself and traverse it to figure out what forms are there and do some custom processing.

For the latter, perhaps something like this?

  def handle_event("add_block", %{"type" => type}, socket) do
    form =
      socket.assigns.form
      |> AshPhoenix.Form.add_form("form[blocks]",
        params: %{
          "_union_type" => type,
          "image" => %{
             "alt" => ""
          }
        }
      )

Works beautifully:

  def handle_event("add_block", %{"type" => type}, socket) do
    form =
      socket.assigns.form
      |> AshPhoenix.Form.add_form("form[blocks]", params: get_params(type))

    {:noreply, assign(socket, :form, form)}
  end

  defp get_params("hero_media" = type), do: %{
      "_union_type" => type,
      "image" => %{
        "url" => "",
        "alt" => "",
        "image_id" => "",
        "modifiers" => %{}
      }
    }

  defp get_params("hero_simple" = type), do: %{ "_union_type" => type }
  defp get_params(type), do: %{ "_union_type" => type }