How to use arguments on nested items in my query using Absinthe in Elixir?

Question

I'm trying to find out how to use arguments on nested items in my query using Absinthe.

What I try to accomplish is this:

{
  users(order: ASC) {
    id
    email
    clients(order: DESC) {
      id
      email
    }
  }
}

Here's my Schema and Type:

  query do
    @desc "Get all users"
    field :users, list_of(:user) do
      arg :order, type: :sort_order, default_value: :asc
      resolve &Resolvers.users/2
    end
  end

  @desc "A user"
  object :user do
    field :id, :id
    field :email, :string
    field :clients, list_of(:user)
  end  

And the resolver:

  def users(_, args, _) do
    args
    |> Enum.reduce(User, fn
      {:order, order}, query ->
        query |> order_by({^order, :email})
    end)
    |> Repo.all |> Repo.preload([:clients])
  end

So my question is how and where should I place the sorting argument for the clients? With the above example I get an error:

"message": "Unknown argument \"order\" on field \"clients\" of type \"User\"."

Answer 1

Put the argument under the clients field:

object :user do
  field :id, :id
  field :email, :string
  field :clients, list_of(:user) do
    arg :order, type: :sort_order, default_value: :asc
    resolve &Resolvers.clients/2
  end
end 

Then write a resolver to handle the sorting:

def clients(user, %{order: clients_order}, _) do
  sorted_clients = user.clients # TODO sort those clients into the desired order
  {:ok, sorted_clients}
end