AE
Ash Elixir•3w ago
abeeshake456

many_to_many in ash

defmodule Consola.Database.ShortUrl do
  use Ash.Resource, domain: Consola.Database, data_layer: AshPostgres.DataLayer

  postgres do
    table "short_urls"
    repo Consola.Repo
  end

  

  actions do
    default_accept :*
    defaults [:create, :read, :update, :destroy]

    create :create_with_full_url do
      default_accept [:related_full_urls, :short_url, :expires_at]
    end
 
  end

  attributes do
    uuid_primary_key :id

    attribute :short_url, :string do
      allow_nil? false
      public? true
    end
 

    attribute :expires_at, :string do
      allow_nil? false
      public? true
    end

    create_timestamp :created_at
    update_timestamp :updated_at
  end

  relationships do
    many_to_many :related_full_urls, Consola.Database.FullUrl do

      through Consola.Database.UrlMapping

      public? true
      writable? true 

      source_attribute :id
      source_attribute_on_join_resource :short_url_id

      destination_attribute :id
      destination_attribute_on_join_resource :full_url_id

    end

  end
end
defmodule Consola.Database.ShortUrl do
  use Ash.Resource, domain: Consola.Database, data_layer: AshPostgres.DataLayer

  postgres do
    table "short_urls"
    repo Consola.Repo
  end

  

  actions do
    default_accept :*
    defaults [:create, :read, :update, :destroy]

    create :create_with_full_url do
      default_accept [:related_full_urls, :short_url, :expires_at]
    end
 
  end

  attributes do
    uuid_primary_key :id

    attribute :short_url, :string do
      allow_nil? false
      public? true
    end
 

    attribute :expires_at, :string do
      allow_nil? false
      public? true
    end

    create_timestamp :created_at
    update_timestamp :updated_at
  end

  relationships do
    many_to_many :related_full_urls, Consola.Database.FullUrl do

      through Consola.Database.UrlMapping

      public? true
      writable? true 

      source_attribute :id
      source_attribute_on_join_resource :short_url_id

      destination_attribute :id
      destination_attribute_on_join_resource :full_url_id

    end

  end
end
Aim: 
params = %{
  short_url: "https://shorturl-example-4.com",
  expires_at: "2025-05-16T10:54:16Z",
  related_full_urls: [%{url: "https://fullurl-example-4.com"}]
}

# to make this API work! 

Consola.Database.ShortUrl|> Ash.Changeset.for_create(:create_with_full_url, params)|> Ash.create!()
params = %{
  short_url: "https://shorturl-example-4.com",
  expires_at: "2025-05-16T10:54:16Z",
  related_full_urls: [%{url: "https://fullurl-example-4.com"}]
}

# to make this API work! 

Consola.Database.ShortUrl|> Ash.Changeset.for_create(:create_with_full_url, params)|> Ash.create!()
What are the different ways to handle creating many_to_many relationship while creating the resource itself? Few notable things are 1. many_to_many has writable? true my understanding is that this should enable me to create the mapping (related_full_urls in the 'through' table) if I pass it as params.
1 Reply
abeeshake456
abeeshake456OP•3w ago
I guess I have to write manage_relationship. 
 actions do
    default_accept :*
    defaults [:create, :read, :update, :destroy]

    create :create_with_full_url do
      default_accept [:short_url, :expires_at]

      argument :related_full_urls, {:array, :map}, allow_nil?: true

      change manage_relationship(:related_full_urls, type: :create)
    end
  end
 actions do
    default_accept :*
    defaults [:create, :read, :update, :destroy]

    create :create_with_full_url do
      default_accept [:short_url, :expires_at]

      argument :related_full_urls, {:array, :map}, allow_nil?: true

      change manage_relationship(:related_full_urls, type: :create)
    end
  end
This did the trick!

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