Question

我有两个应用程序，一个用作API，具有只读访问权限和一个主要应用程序。在主应用程序中，我有很多通过多态关系。主应用程序中的模型看起来像这样，并且效果很好：

class Category < ActiveRecord::Base
  has_many :category_associations
  has_many :posts, through: :category_associations
  has_many :pages, through: :category_associations
end

class Post < ActiveRecord::Base
  has_many :category_associations, as: :associated
  has_many :categories, as: associated, through: :category_associations, source: :post
end

class Page < ActiveRecord::Base
  has_many :category_associations, as: :associated
  has_many :categories, as: associated, through: :category_associations, source: :post
end

class CategoryAssociation
  belongs_to :category
  belongs_to :associated, polymorphic: true
end

现在对于第二个应用程序，我需要访问相同的表，但我的类名称会有所不同，这会影响即使使用source_type也无法覆盖的类型字段。：

class Category < ActiveRecord::Base
  has_many :category_associations
  has_many :articles, through: :category_associations
  has_many :static_contents, through: :category_associations
end

class Article < ActiveRecord::Base
  self.table_name = 'posts'

  has_many :category_associations, as: :associated
  has_many :categories, as: associated, through: :category_associations, source: :article, source_type: 'Post'
end

class StaticContent < ActiveRecord::Base
  self.table_name = 'pages'

  has_many :category_associations, as: :associated
  has_many :categories, as: associated, through: :category_associations, source: :static_content, source_type: 'Page'
end

class CategoryAssociation
  belongs_to :category
  belongs_to :associated, polymorphic: true
end

我收到以下错误：

=> Posts.first.categories

# ActiveRecord::HasManyThroughAssociationPointlessSourceTypeError: Cannot have a has_many :through association 'Post#categories' with a :source_type option if the 'CategoryAssociation#category' is not polymorphic. Try removing :source_type on your association.

当我从类别

中抓取帖子时，似乎也是如此

Answer 1

您是否尝试将polymorphic:true置于类别belongs_to？这似乎是错误消息指向的方向，但我不确定

class CategoryAssociation
  belongs_to :category, polymorphic: true
  ...
end

has_many通过自定义类型的多态

1 个答案: