问题分组has_many通过收集

Question

我遇到了以下问题：group和：uniq标签作为has_many通过集合定义的选项。我在我的系统上定义了许多三重模型关联，我想列出分组的元素以避免（实际）重复。我的主要模型看起来像这样：

class Trip < ActiveRecord::Base
  belongs_to :agent
  has_many :trips_destinations, :class_name => "TripsDestination"
  has_many :destinations, :through => :trips_destinations

  has_and_belongs_to_many :vibes, join_table: :trips_vibes
  has_and_belongs_to_many :verbs, join_table: :trips_verbs

  has_many :trips_destinations_activities, :class_name => "TripsDestinationsActivity"
  has_many :activities, :through => :trips_destinations_activities, :uniq => true

  has_many :trips_destinations_hotels, :class_name => "TripsDestinationsHotel"
  has_many :hotels, :through => :trips_destinations_hotels

  has_many :trips_destinations_recommended_places, :class_name => "TripsDestinationsRecommendedPlace"
  has_many :recommended_places, :through => :trips_destinations_recommended_places

  has_many :trips_destinations_transportations, :class_name => "TripsDestinationsTransportation"
  has_many :transportations, :through => :trips_destinations_transportations

...
...

end

任何人都知道如何列出为什么避免重复给出对[trip_id，destination_id]？ 为什么要重复这些？

我的rails版本是4，下面的图片显示了将分组选项传递给has_many关系时的错误消息。

请帮忙！

Answer 1

对于Rails 4，uniq的语法不正确。

has_many :activities, -> { uniq }, :through => :trips_destinations_activities

独特现在有scope syntax。