Identity on `attribute :some_attribute, {:array , EmbeddedResource}`

So if I have the following resource.

defmodule Resource do
...
  actions do
    defaults [:create, :read, :update, :destroy]
  end

  attributes do
    ...
    uuid_primary_key :id

    attribute :some_attribute, {:array, EmbeddedResource}
    ...
  end

  identities do
    ...
    identity :unique_some_attribute, [:some_attribute]
    ...
  end
end

defmodule Resource do
...
  actions do
    defaults [:create, :read, :update, :destroy]
  end

  attributes do
    ...
    uuid_primary_key :id

    attribute :some_attribute, {:array, EmbeddedResource}
    ...
  end

  identities do
    ...
    identity :unique_some_attribute, [:some_attribute]
    ...
  end
end

And the following embedded resource.

defmodule EmbeddedResource do
  use Ash.Resource,
    data_layer: :embedded

  attributes do
    attribute :key, :string do
      constraints trim?: true
      allow_nil? false
    end

    attribute :value, :string do
      constraints trim?: true
      allow_nil? false
    end
  end

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

defmodule EmbeddedResource do
  use Ash.Resource,
    data_layer: :embedded

  attributes do
    attribute :key, :string do
      constraints trim?: true
      allow_nil? false
    end

    attribute :value, :string do
      constraints trim?: true
      allow_nil? false
    end
  end

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

If I do the following changeset twice.

Resource
|> Ash.Changeset.for_create(:create, %{})
|> Api.create()

Resource
|> Ash.Changeset.for_create(:create, %{})
|> Api.create()

It succeeds once and then fails a second time, which is as expected. The :unique_some_attribute identity prevents two records with some_attribute: nil. However If the next changeset is repeated twice.

Resource
|> Ash.Changeset.for_create(:create, %{some_attribute: [%{key: "color", value: "ash"}]})
|> Api.create()

Resource
|> Ash.Changeset.for_create(:create, %{some_attribute: [%{key: "color", value: "ash"}]})
|> Api.create()

Two resources with the same :some_attribute field are created. I had hoped this to be prevented by the :unique_some_attribute identity. The resulting records look something like the following.

%Resource<
  ...
  id: "uuid_1",
  some_attribute: [
    %EmbeddedResource<
      ...
      autogenerated_id: "autogenerated_uuid_1",
      key: "color",
      value: "ash"
    >
  ]
>

%Resource<
  ...
  id: "uuid_2",
  some_attribute: [
    %EmbeddedResource<
      ...
      autogenerated_id: "autogenerated_uuid_2",
      key: "color",
      value: "ash"
    >
  ]
>

%Resource<
  ...
  id: "uuid_1",
  some_attribute: [
    %EmbeddedResource<
      ...
      autogenerated_id: "autogenerated_uuid_1",
      key: "color",
      value: "ash"
    >
  ]
>

%Resource<
  ...
  id: "uuid_2",
  some_attribute: [
    %EmbeddedResource<
      ...
      autogenerated_id: "autogenerated_uuid_2",
      key: "color",
      value: "ash"
    >
  ]
>

I assume the autogenerated_id fields being unique is preventing the desired outcome. Would that work and can they be disabled?

3 Replies

ZachDaniel•2y ago

identities on embedded resources are only applied within lists of that attribute, not all instances of the embedded resource Its unlikely that would ever be supported automatically If you want to ensure that you have uniqueness in that way you would need to do something else, some options: 1. make that a resource and relationship. If you want cross-record uniqueness, it seems natural to me that this thing you're creating is not really an embedded resource (scoped to parent) but a regular resource 2. implement some kind of custom validation that checks for conflicts before committing 3. implement some database level constraint

morfertawOP•2y ago

I'm not sure how I would do so with a resource and relationship. Regardless thanks for the response.

ZachDaniel•2y ago

What I mean is that instead of using an embedded resource, you'd make a regular resource and then do:

has_many :things, YourThing

has_many :things, YourThing

Then if you put an identity on that related thing you'll have global uniqueness

Gaming

Programming

Identity on `attribute :some_attribute, {:array , EmbeddedResource}`

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