我正在尝试在Post模型中使用viewer_ids来保存user_ids，并将User模型中的Viewed_ids保存到已查看的post_ids。当使用Rspec进行测试添加/删除并访问来自User的关系时，它很有用。但是，当我使用RABL来查看后期用户数据时，它会被混淆并给我一个模糊的关系。
#Post class
belongs_to :user
has_and_belongs_to_many :viewers, class_name: 'User', inverse_of: :viewed
#User class
has_many :users
has_and_belongs_to_many :viewed, class_name: 'Post', inverse_of: :viewers
Problem:
Ambiguous relations :posts, :viewed defined on User.
Summary:
When Mongoid attempts to set an inverse document of a relation in memory, it needs to know which relation it belongs to. When setting :user, Mongoid looked on the class Post for a matching relation, but multiples were found that could potentially match: :posts, :viewed.
Resolution:
On the :user relation on Post you must add an :inverse_of option to specify the exact relationship on User that is the opposite of :user.
那么问题是什么，我正在定义关系和它们的倒数。是否不可能在关系的反转中得到不同的数据？
答案 0 :(得分：6)
问题在于在模型上具有相同类的多个关系。因此，一旦添加了n-n，每侧就有2个用户关系和2个帖子关系。
#Post class
belongs_to :user, inverse_of: :posts
has_and_belongs_to_many :viewers, class_name: 'User', inverse_of: :viewed
#User class
has_many :posts, inverse_of: :user
has_and_belongs_to_many :viewed, class_name: 'Post', inverse_of: :viewers