Ash Elixir•2y ago

many_to_many update problem

I have a product which has many_to_many tags. Creating works. Updating doesn't. Here's the resource code: lib/app/shop/resources/product.ex

defmodule App.Shop.Product do
  use Ash.Resource, data_layer: Ash.DataLayer.Ets

  attributes do
    uuid_primary_key :id
    attribute :name, :string
    attribute :price, :decimal
  end

  relationships do
    many_to_many :tags, App.Shop.Tag do
      through App.Shop.ProductTag
      source_attribute_on_join_resource :product_id
      destination_attribute_on_join_resource :tag_id
    end
  end

  actions do
    defaults [:read, :destroy]

    create :create do
      primary? true
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end

    create :update do
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end
  end

  code_interface do
    define_for App.Shop
    define :create
    define :read
    define :by_name, get_by: [:name], action: :read
    define :update
    define :destroy
  end
end

defmodule App.Shop.Product do
  use Ash.Resource, data_layer: Ash.DataLayer.Ets

  attributes do
    uuid_primary_key :id
    attribute :name, :string
    attribute :price, :decimal
  end

  relationships do
    many_to_many :tags, App.Shop.Tag do
      through App.Shop.ProductTag
      source_attribute_on_join_resource :product_id
      destination_attribute_on_join_resource :tag_id
    end
  end

  actions do
    defaults [:read, :destroy]

    create :create do
      primary? true
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end

    create :update do
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end
  end

  code_interface do
    define_for App.Shop
    define :create
    define :read
    define :by_name, get_by: [:name], action: :read
    define :update
    define :destroy
  end
end

Here's what I do in the iex:

iex(1)> good_deal_tag = App.Shop.Tag.create!(%{name: "Good deal"})
iex(2)> yellow_tag = App.Shop.Tag.create!(%{name: "Yellow"})
iex(3)> App.Shop.Product.create!(%{
            name: "Banana",
            tags: [good_deal_tag, yellow_tag]
            })
iex(4) banana = App.Shop.Product.by_name!("Banana", load: [:tags])

iex(1)> good_deal_tag = App.Shop.Tag.create!(%{name: "Good deal"})
iex(2)> yellow_tag = App.Shop.Tag.create!(%{name: "Yellow"})
iex(3)> App.Shop.Product.create!(%{
            name: "Banana",
            tags: [good_deal_tag, yellow_tag]
            })
iex(4) banana = App.Shop.Product.by_name!("Banana", load: [:tags])

That all works nicely. But I can not update the products tags or the even the product:

iex(16)> App.Shop.Product.update!(banana, %{tags: [yellow_tag]})
** (FunctionClauseError) no function clause matching in Keyword.split/2
[...]
iex(16)> App.Shop.Product.update!(banana, %{name: "test"})
** (FunctionClauseError) no function clause matching in Keyword.split/2

iex(16)> App.Shop.Product.update!(banana, %{tags: [yellow_tag]})
** (FunctionClauseError) no function clause matching in Keyword.split/2
[...]
iex(16)> App.Shop.Product.update!(banana, %{name: "test"})
** (FunctionClauseError) no function clause matching in Keyword.split/2

How can I fix this?

6 Replies

Theosaurus•2y ago

Hey there! I could be totally wrong but I think from memory if something is stated as an argument you have to just pass it as App.Shop.Product.update!(banana, [yellow_tag]) rather than in a struct (I think), and additionally may need to include args: [tags] in your code interface for the update action. Hopefully that helps? I could be totally wrong as I tend to always mix up argument and accepts and the correct syntax for calling them 😅

Stefan WintermeyerOP•2y ago

I tried

iex(5)> App.Shop.Product.update!(banana, [yellow_tag])
** (FunctionClauseError) no function clause matching in anonymous fn/2 in Keyword.split/2

iex(5)> App.Shop.Product.update!(banana, [yellow_tag])
** (FunctionClauseError) no function clause matching in anonymous fn/2 in Keyword.split/2

But I don't know how to do the args: [tags] thing and I am lost in the documentation. @Zach Daniel Can you help me out here? I'd like to record the tutorial.

ZachDaniel•2y ago

You’ve defined your action called :update but is a create action So the first argument would be different, causing the error you see We should provide better error there of course But it should work if you change it to an update action I.e create :update

Stefan WintermeyerOP•2y ago

I draw a blank here. The code already says:

    create :update do
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end

    create :update do
      argument :tags, {:array, :map}
      change manage_relationship(:tags, type: :append_and_remove, on_no_match: :create)
    end

Where would I include an other create?

ZachDaniel•2y ago

It should say update :update Not create :update

Stefan WintermeyerOP•2y ago

Ahhh! Thanks! It works.

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many_to_many update problem

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