Union type in :array does not work properly on type change

[revati]

im fallowing this guide: https://hexdocs.pm/ash_phoenix/union-forms.html
but my union type is in list. Im get error:

[error] GenServer #PID<0.1780.0> terminating
** (KeyError) key :form_keys not found in: [
  #AshPhoenix.Form<
    resource: MyResourceWrapper,
    action: :update,
    type: :update,
    params: %{"_union_type" => "static"},
...
]

[zachdaniel]

I will address this early next week. If you have time to put together a test/repro that will help 🙇

[zachdaniel]

So we have tests for this behavior, and as far as I can tell it works, so I'll need to see some sample code or a reproduction to go any further with it.

[adampointer]

Hi. I have the exact same bug. I am stumped but it is probably me doing something stupid.

It is the same as the OP, I have an array of union types and when I try and change type as per the tutorial on Union Forms, I get this error from forms.ex.

[zachdaniel]

Are you on the latest version of ash_phoenix and ash? Some fixes were made recently to both.

[adampointer]

I am on the latest release ash phoenix v2.1.2

I can invite you to my repo if that's going to help

[zachdaniel]

We can that, yes. Please be sure to provide very clear reproduction steps and/or a failing test illustrating the issue.

[adampointer]

Awesome. I will get a test case written after the weekend.

[adampointer]

Hey. I fixed this on my own. The issue I had was from following the examples on this page https://hexdocs.pm/ash_phoenix/union-forms.html.

In this event handler:

def handle_event("type-changed", %{"_target" => path} = params, socket) do
  new_type = get_in(params, path)
  # The last part of the path in this case is the field name
  path = :lists.droplast(path)

  form =
    socket.assigns.form
    |> AshPhoenix.Form.remove_form(path)
    |> AshPhoenix.Form.add_form(path, params: %{"_union_type" => new_type})

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

path was a list of strings like ["my_form", "content", "0"]. This was causing the above error to be thrown from the AshPhoenix.Form.add_form function. When I set the path as a string instead, it worked.

def handle_event("type-changed", %{"_target" => path} = params, socket) do
    new_type = get_in(params, path)
    index =
      path
      |> :lists.droplast()
      |> List.last()

    form =
      socket.assigns.form
      |> AshPhoenix.Form.remove_form("my_form[content][#{index}]")
      |> AshPhoenix.Form.add_form("my_form[content]",
        params: %{"_union_type" => new_type}
      )

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

The one issue I have now, is that if I have more than one item in the list of subforms, when I change the type of the first item, it changes the type of all subsequent items too. Although that's not really a blocker, I might just disable the type select field once a new subform has been added. I am not sure this is the optimal fix for this.

[zachdaniel]

Hm....this does still seem like something we should fix internally. Especially given that you aren't able to have a mixed list of types. If you have a chance to reproduce in a test that would be awesome :)