在rails中添加具有不同关联类型的对象答案

【问题标题】：Adding objects with different association types in rails在rails中添加具有不同关联类型的对象
【发布时间】：2014-03-23 18:43:02
【问题描述】：

以下是我的三个模型：许多用户可以通过关联模型拥有许多产品（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

为了给用户添加一个“中等”的关联.强度产品，我通常会这样做：

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

我的问题是我将如何做同样的事情并向用户添加产品但“强”关联。强度初始化？

【问题讨论】：

标签： ruby-on-rails ruby-on-rails-4 model model-associations

【解决方案1】：

你可以用 strong by 做同样的事情

user.strong_associated_products << product

你可能需要这样设置你的关系：

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

【讨论】：

我刚刚意识到这似乎不起作用，因为“associations.strength”没有设置为“strong”

【解决方案2】：

添加到@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

【讨论】：