Applying constraints to embedded union types

I have a resource when an embedded array of union types:

defmodule MyApi.Package
  attributes do
    ...
    attribute :options, {:array, PackageOption}, allow_nil?: false
  end
end

defmodule MyApi.Package
  attributes do
    ...
    attribute :options, {:array, PackageOption}, allow_nil?: false
  end
end

defmodule MyApi.PackageOption do
  use Ash.Type.NewType,
    subtype_of: :union,
    constraints: [
      types: [
        boolean: [
          type: MyApi.PackageOption.Boolean
          tag: :type,
          tag_value: :boolean
        ],
        string: [
          type: MyApi.PackageOption.String
          tag: :type,
          tag_value: :string
        ]
      ]
    ]
end

defmodule MyApi.PackageOption.Boolean do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :key, :ci_string, allow_nil?: false, constraints: [match: ~r/^[a-z0-9-]+$/]
    attribute :value, :boolean
    attribute :type, :atom, constraints: [one_of: [:boolean]]
    attribute :enabled, :boolean, allow_nil?: false
  end

  identities do
    identity :key, [:key]
  end
end

defmodule MyApi.PackageOption.String do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :key, :ci_string, allow_nil?: false, constraints: [match: ~r/^[a-z0-9-]+$/]
    attribute :value, :text
    attribute :type, :atom, constraints: [one_of: [:string]]
    attribute :enabled, :boolean, allow_nil?: false
  end

  identities do
    identity :key, [:key]
  end
end

defmodule MyApi.PackageOption do
  use Ash.Type.NewType,
    subtype_of: :union,
    constraints: [
      types: [
        boolean: [
          type: MyApi.PackageOption.Boolean
          tag: :type,
          tag_value: :boolean
        ],
        string: [
          type: MyApi.PackageOption.String
          tag: :type,
          tag_value: :string
        ]
      ]
    ]
end

defmodule MyApi.PackageOption.Boolean do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :key, :ci_string, allow_nil?: false, constraints: [match: ~r/^[a-z0-9-]+$/]
    attribute :value, :boolean
    attribute :type, :atom, constraints: [one_of: [:boolean]]
    attribute :enabled, :boolean, allow_nil?: false
  end

  identities do
    identity :key, [:key]
  end
end

defmodule MyApi.PackageOption.String do
  use Ash.Resource, data_layer: :embedded

  attributes do
    uuid_primary_key :id
    attribute :key, :ci_string, allow_nil?: false, constraints: [match: ~r/^[a-z0-9-]+$/]
    attribute :value, :text
    attribute :type, :atom, constraints: [one_of: [:string]]
    attribute :enabled, :boolean, allow_nil?: false
  end

  identities do
    identity :key, [:key]
  end
end

When doing a create or update on the parent (MyApi.Package) with an option that has an invalid key (see constraint), it's not returning %Ash.Error.Invalid{} as expected. I've tried applying a validation in lieu of an attribute constraint, but the validation is never called. Additionally, the identity is not enforced.

9 Replies

ZachDaniel•2y ago

So if you provide a record with an invalid key what happens? Also yeah I think you're going to need to validate the uniqueness yourself or we're going to need to add explicit support for unique checking unions if they all have a key and all have an identity on it

Robert GraffOP•2y ago

      Package.update(
        package,
        %{
          options: [
            %Ash.Union{
              type: :boolean,
              value: %PackageOption.Boolean{
                type: :boolean,
                value: false,
                key: "not a valid key",
                enabled: true
              }
            }
          ]
        }
      )

      {:ok, %MyApi.Package{
        ...
        options: [
          %Ash.Union{
            value: #PackageOption.Boolean<__lateral_join_source__: nil, __meta__: #Ecto.Schema.Metadata<:built, "">, id: "e8668815-061c-4f86-bfa7-4d166fd1dba2", key: "true!", value: true, type: :boolean, enabled: true, aggregates: %{}, calculations: %{}, __order__: nil, ...>, 
            type: :boolean
            }
        ]
      }}

      Package.update(
        package,
        %{
          options: [
            %Ash.Union{
              type: :boolean,
              value: %PackageOption.Boolean{
                type: :boolean,
                value: false,
                key: "not a valid key",
                enabled: true
              }
            }
          ]
        }
      )

      {:ok, %MyApi.Package{
        ...
        options: [
          %Ash.Union{
            value: #PackageOption.Boolean<__lateral_join_source__: nil, __meta__: #Ecto.Schema.Metadata<:built, "">, id: "e8668815-061c-4f86-bfa7-4d166fd1dba2", key: "true!", value: true, type: :boolean, enabled: true, aggregates: %{}, calculations: %{}, __order__: nil, ...>, 
            type: :boolean
            }
        ]
      }}

ZachDaniel•2y ago

Hm….something seems strange there Oh You’re providing a structure there It assumes you got structs by casting them To test the casting you’d want to provide something like [%{key: “not a valid key”, type: :boolean, value: false}]

Robert GraffOP•2y ago

Wow, ok. Using a map instead of a struct, the constraints and the validations are applied. Are the validations supposed to be skipped if there's no casting?

ZachDaniel•2y ago

Yeah, the idea is that you provided an already valid value if providing structs (because the outside world can’t provide a struct, like over an api)

Robert GraffOP•2y ago

Got it. That makes sense now. For other reasons, I've not been able to get forms working and I haven't tested the apis

ZachDaniel•2y ago

Yeah, forms against unions are currently something the framework doesn’t handle for you. We can, just need to add code to ash_phoenix And so what you end up needing to do is essentially roll your own, switching the form behavior based on the union type.

Robert GraffOP•2y ago

I can switch the behaviour for the union type pretty easily, but I'm not sure I'm adding forms correctly. I'm trying to get it working with just one type to start.

    create_feature_form =
      AshPhoenix.Form.for_create(Package, :create,
        api: MyApi,
        forms: [
          variants: [
            type: :list,
            resource: PackageOption.Boolean, # or is it PackageOption Union?
            create_action: :create
          ]
        ]
      )
      |> to_form()

    create_feature_form =
      AshPhoenix.Form.for_create(Package, :create,
        api: MyApi,
        forms: [
          variants: [
            type: :list,
            resource: PackageOption.Boolean, # or is it PackageOption Union?
            create_action: :create
          ]
        ]
      )
      |> to_form()

[error] GenServer #PID<0.1349.0> terminating
** (UndefinedFunctionError) function Kickplan.Environments.FeatureVariant.__struct__/0 is undefined or private
    (kickplan 0.1.0) Kickplan.Environments.FeatureVariant.__struct__()

[error] GenServer #PID<0.1349.0> terminating
** (UndefinedFunctionError) function Kickplan.Environments.FeatureVariant.__struct__/0 is undefined or private
    (kickplan 0.1.0) Kickplan.Environments.FeatureVariant.__struct__()

The union raises the struct error, but adding the form for one of the variants leads to other errors

ZachDaniel•2y ago

I think what you might need to do is do it without auto forms entirely and manage the nested forms yourself. That’s without us adding special support for it in ash_phoenix. I’m currently trying to think of a better way, and/or how we’d be able to support a dynamic config for nested forms. I’ll have to tackle it when I’m back from vacation. In the meantime, you should be able to “roll your own” here by looping over the current values and storing a list of forms in the socket assigns, and handling validation that way. Actually if you just don’t add a form config for it, you should just be able to loop over the field value. And create a new form on the fly

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Applying constraints to embedded union types

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