blog_example_p1.3.ex

defmodule ProductVehicle do
  def vehicles_that_fit_product(query \\ ProductVehicle, product_id) do
    query
    |> join(:inner,
            [products_vehicles],
            product in assoc(products_vehicles, :product))
    |> join(:inner,
            [products_vehicles],
            vehicle in assoc(products_vehicles, :vehicle))
    |> join(:inner,
            [_, _, vehicle],
            vehicle in assoc(vehicle, :vehicle_model))
  end

  def for_year(query \\ ProductVehicle, year) do
    where(query, [_pa, _p, v], v.year == ^year)
  end
end

# Which would be used like this:
ProductVehicle
|> vehicles_that_fit_product(42)
|> for_year("1961")