ActiveRecord:地点和路线有哪些关联?

你的路线需要与两个地方相关联——起点和终点。

因此,一种选择是:

class Place < ApplicationRecord
  has_many :routes_as_start, class_name: "Route", foreign_key: :start_place_id
  has_many :routes_as_end,   class_name: "Route", foreign_key: :end_place_id
end

class Route < ApplicationRecord
  belongs_to :start_place, class_name: "Place"
  belongs_to :end_place,   class_name: "Place"
end

class Place < ApplicationRecord
  has_many :route_ends,
  has_many :routes, through: :ends
end

class RouteEnd
  belongs_to :place
  belongs_to :route
end

class Route < ApplicationRecord
  has_many :route_ends
  has_many :places, :through :route_end
end

在这种情况下, :has_many :has_two

这使您可以更轻松地找到在特定位置终止的所有路线,而不必考虑它们是“起点”或“终点”。