blog_example_models.ex

defmodule VehicleMake do
  schema "vehicle_makes" do
    field :name, :string

    has_many :vehicle_models, VehicleModel
    has_many :vehicles, through: [:vehicle_models, :vehicles]
  end
end

defmodule VehicleModel do
  schema "vehicle_models" do
    field :name, :string

    belongs_to :vehicle_make, VehicleMake, foreign_key: :vehicle_make_id
    has_many :vehicles, Vehicle
  end
end

defmodule Vehicle do
  schema "vehicles" do
    field :year, :string

    belongs_to :vehicle_model, VehicleModel, foreign_key: :vehicle_model_id
  end
end

defmodule ProductVehicle do
  schema "products_vehicles" do
    belongs_to :product, Product
    belongs_to :vehicle, Vehicle
  end
end