I’ve been banging my head with using custom types in a resource with AshAdmin. In short, the fields for the custom types keep resetting when touching other fields.

I’m pretty sure that I’m not holding it wrong and made a reproduction repo with an extensive write-up in the README. The reproduction has resource with a custom type attribute with the implementation lifted from docs as well as an attribute of type :money from AshMoney.

Is there anything in particular one should consider when using custom types in AshAdmin or could there be a potential issue there?

The README write-up:

Reproduction for custom Ash.Type question

This is a reproduction of an issue I’ve had with custom types.

In short, using the example implementation for float from the documentation resets the attribute upon validation when changing other attributes in the changeset (AshAdmin).

This app has a domain Entities with one resource Entity having the attributes:

• :name of the built-in type :string,
• :size of the custom type :custom_float defined in this codebase and
• :balance of the custom type :money from AshMoney (as installed by Igniter).

The body of the function that implements the custom type :custom_float is lifted verbatim from the example in the documentation:

defmodule DemoRepo.Types.CustomFloat do
  use Ash.Type

  @impl Ash.Type
  def storage_type(_), do: :float

  @impl Ash.Type
  def cast_input(nil, _), do: {:ok, nil}

  def cast_input(value, _) do
    Ecto.Type.cast(:float, value)
  end

  @impl Ash.Type
  def cast_stored(nil, _), do: {:ok, nil}

  def cast_stored(value, _) do
    Ecto.Type.load(:float, value)
  end

  @impl Ash.Type
  def dump_to_native(nil, _), do: {:ok, nil}

  def dump_to_native(value, _) do
    Ecto.Type.dump(:float, value)
  end
end

The type :custom_float is, as far as I understand it, duly configured in config/config.exs like so:

config :ash,
  # yada yada yada
  custom_types: [
    money: AshMoney.Types.Money,
    custom_float: DemoRepo.Types.CustomFloat
  ]

When creating an Entity in AshAdmin using a default :create action that accepts :name, :size and :balance:

defaults [
  :read,
  :destroy,
  create: [:name, :size, :balance], # <- This bad boy right here
  update: [:name, :size, :balance]
]

it is possible to enter a value for :size in the form and have it passed to the changeset for persistence. However, touching any other field - thus triggering a validation - while :size has a value will set :size to nil. The same goes for the :balance attribute.

Creating an Entity using a create action :instrumented_create:

create :instrumented_create do
  accept [:name, :size]

  change fn changeset, _context -> changeset |> dbg() end
end

yields the same result.

Looking at the output after having put first name: "A" and then size: 1 in the form:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "A", size: 1.0},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

and then looking after again editing the :name field in the form one gets:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "Ab", size: 1.0},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

where size: 1.0 actually shows up in the in the changeset, but has disappeard in the form.

Touching :name again, quite reasonably, results in the following since :size was not left in the form and therefore didn’t make it to the params:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "Abc", size: nil},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

As for doing the same but with :balance (that is a “known quantity”):

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "A", balance: Money.new(:SEK, "1")},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

touching :name again whereby the :balance field in the form is reset:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "Ab", balance: Money.new(:SEK, "1")},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

and then one more time touching :name:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :create,
  action: :instrumented_create,
  attributes: %{name: "Abc", balance: nil},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: nil,
    name: nil,
    size: nil,
    balance: nil,
    __meta__: #Ecto.Schema.Metadata<:built, "entities">
  },
  valid?: true
>

Finally, opening a record for updating with :instrumented_update puts out:

changeset #=> #Ash.Changeset<
  domain: DemoRepo.Entities,
  action_type: :update,
  action: :instrumented_update,
  attributes: %{},
  relationships: %{},
  errors: [],
  data: %DemoRepo.Entities.Entity{
    id: "fef55f7d-7eaf-418f-80e9-6425be8c7b66",
    name: "Joe",
    size: nil,
    balance: Money.new(:SEK, "3"),
    __meta__: #Ecto.Schema.Metadata<:loaded, "entities">
  },
  valid?: true
>

leaving the field :balance with the value nil in the form. Since one cannot save both :balance and :size, :size was already nil when opening the :instrumented_update form. The same thing happens with the default :update form.

Environment

• macOS 15.6
• erlang 27.3.4
• elixir 1.18.4-otp-27
• ash 3.5.33
• ash_admin 0.13.13 ← Only tested in AshAdmin
• ash_money 0.2.3
• ash_phoenix 2.3.12
• ash_postgres 2.6.14
• ash_sql 0.2.89
• phoenix_live_view 1.1.3 ← ?

BTW, LiveView complains about asset versions:

LiveView asset version mismatch. JavaScript version 1.1.0-rc.3 vs. server 1.1.3. To avoid issues, please ensure that your assets use the same version as the server.

Generation

The application was generated with the following commands:

mix archive.install hex igniter_new --force
mix archive.install hex phx_new 1.8.0-rc.4 --force

mix igniter.new demo_repo --with phx.new --install ash,ash_phoenix \
  --install ash_postgres,ash_admin --install ash_money --yes

cd demo_repo && mix ash.setup

Written by a human being