ecto question

many.ex

# User can have many Place
# Place can have many User
# User has a role for a Place he belongs to

# 1) ecto schemas

  schema "accounts_users" do
    # fields
    many_to_many :map_places, Place, join_through: UserPlace
  end
  
  schema "map_places" do
    # fields
    many_to_many :accounts_users, User, join_through: UserPlace
  end
  
  schema "users_places" do
    field :user_id, :id
    field :place_id, :id
    field :role_id, :id
  end
  
  # 2) graphql
  # 2.1) query I'm running
  query {
    places {
      id
      users {
        userId
        roleId
      }
    }
  }
  
  # 2.2) absinthe types
  object :map_place do
    field :id, :id
    field :users, list_of(:user_place), resolve: assoc(:users_places)
  end
  
  object :user_place do
    field :user_id, :id
    field :place_id, :id
    field :role_id, :id
  end
  
  # 2.3) absinthe query
  query do
    field :places, type: list_of(:map_place) do
      resolve &Resolvers.all/2
    end
  end
  
  # resolver
  def all(_args, _info) do
    {:ok, Map.list_places()}
  end
  
  # phoenix Map context
  def list_places do
    Repo.all(Place)
  end