Question

以下是我的三个模型：许多用户可以通过关联模型获得许多产品（反之亦然）。

class Product < ActiveRecord::Base
  has_many :associations
  has_many :users, :through => :associations
end

class User < ActiveRecord::Base
  has_many :associations
  has_many :products, :through => :associations
  has_many :medium_associated_products, :class_name => "Product", :through => :associations, :source => :product, :conditions => ["associations.strength = ?", "medium"]
  has_many :strong_associated_products, :class_name => "Product", :through => :associations, :source => :product, :conditions => ["associations.strength = ?", "strong"]  
end

class Association < ActiveRecord::Base
  belongs_to :user
  belongs_to :product
end

要向用户添加“中等”association.stngthngth产品，我通常会这样做：

user.products << product  #associations.strength is by default "medium"

我的问题是我如何做同样的事情并向用户添加产品但是具有“强”关联。强度初始化？

Answer 1

您可以通过

执行相同的操作

user.strong_associated_products << product

您可能需要以这种方式设置您的关系：

class User < ActiveRecord::Base
  has_many :medium_associations, class_name: 'Association', condition: ["associations.strength = ?", "medium"]
  has_many :strong_associations, class_name: 'Association', condition: ["associations.strength = ?", "strong"]
  has_many :medium_associated_products, class_name: 'Product', through: :medium_associations, source: :product
  has_many :strong_associated_products, class_name: 'Product', through: :strong_associations, source: :product

结束

Answer 2

添加@ sonnyhe2002的答案。我最终使用了回调，例如

has_many :strong_associations, class_name: 'Association', condition: ["associations.strength = ?", "strong"], add_before: :set_the_strength

然后

def set_the_strength(obj)
   obj[:strength] = "strong"
end

在rails中添加具有不同关联类型的对象

2 个答案: