Ash Elixir•3y ago

How do you set an attribute to the join resource when creating?

For example, I have a User and an Org, joined by a many_to_many through a Join Resource UserOrg. UserOrg has an attribute :role. How do I set the role on the UserOrg when creating an Org?

create :create do
  accept [:name]
  argument :user_id, :binary

  change fn changeset, %{actor: actor} = _context ->
    changeset |> Ash.Changeset.set_argument(:user_id, actor.id)
  end

  change manage_relationship(:user_id, :users, type: :append_and_remove)
  # ^^^ somehow set :role to :owner in this relationship
end

create :create do
  accept [:name]
  argument :user_id, :binary

  change fn changeset, %{actor: actor} = _context ->
    changeset |> Ash.Changeset.set_argument(:user_id, actor.id)
  end

  change manage_relationship(:user_id, :users, type: :append_and_remove)
  # ^^^ somehow set :role to :owner in this relationship
end

11 Replies

ZachDaniel•3y ago

Read through the options here: https://ash-hq.org/docs/module/ash/latest/ash-changeset#function-manage_relationship-4

Ash HQ

Module: Ash.Changeset

View the documentation for Ash.Changeset on Ash HQ.

ZachDaniel•3y ago

There is a format for determining which fields get sent to the join table although, FWIW, in your case you could just manage the join relationship directly

  accept [:name]
  change fn changeset, %{actor: actor} = _context ->
    changeset
    |> Ash.Changeset.manage_relationship(:users_join_relationship, %{
      user_id: actor.id,
      role: :owner
    })
  end

  accept [:name]
  change fn changeset, %{actor: actor} = _context ->
    changeset
    |> Ash.Changeset.manage_relationship(:users_join_relationship, %{
      user_id: actor.id,
      role: :owner
    })
  end

Arjun BajajOP•3y ago

No such relationship users_join_relationship for resource Org I tried with users_join_assoc too, but then it sets that to an empty list.

ZachDaniel•3y ago

ah, yeah sorry it should be users_join_assoc ah, perhaps it needs to be a list not a map? you should be able to manage it that way though oh my example didn't have any options

  change fn changeset, %{actor: actor} = _context ->
    changeset
    |> Ash.Changeset.manage_relationship(:users_join_relationship, [%{
      user_id: actor.id,
      role: :owner
    }], type: :append_and_remove)
  end

  change fn changeset, %{actor: actor} = _context ->
    changeset
    |> Ash.Changeset.manage_relationship(:users_join_relationship, [%{
      user_id: actor.id,
      role: :owner
    }], type: :append_and_remove)
  end

Arjun BajajOP•3y ago

With :append_and_remove it gives an error record with role: :owner | user_id: "EF6DF726A6" not found. However, with :create instead, it gives this error: Input invalid: relationship user is required. I'm guessing this is complaining that the user on the join resource is not provided through here.

ZachDaniel•3y ago

oh, yeah type: :create

Arjun BajajOP•3y ago

That doesn't work either Input invalid: relationship user is required.

ZachDaniel•3y ago

I assume on the join resource you have belongs_to :user, ... set attribute_writable? true on the belongs_to relationships

Arjun BajajOP•3y ago

that works! 🚀 For future readers, after setting attribute_writable? true on your join resource association, here's the final create function which works:

create :create do
  accept [:name, :desc]
  argument :user_id, :binary

  change fn changeset, %{actor: actor} = _context ->
    join = %{user_id: actor.id, role: :owner}
    changeset |> Ash.Changeset.manage_relationship(:users_join_assoc, join, type: :create)
  end
end

create :create do
  accept [:name, :desc]
  argument :user_id, :binary

  change fn changeset, %{actor: actor} = _context ->
    join = %{user_id: actor.id, role: :owner}
    changeset |> Ash.Changeset.manage_relationship(:users_join_assoc, join, type: :create)
  end
end

Thanks a lot for all your help @Zach Daniel! :ashley:

ZachDaniel•3y ago

You probably don’t need the user_id argument anymore

Arjun BajajOP•3y ago

Yes, thanks!

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How do you set an attribute to the join resource when creating?

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