覆盖has_many上的ActiveRecord <<运算符:通过关系,接受连接模型的数据

Question

我有三个类:人员,职位和目录.

• 一个人has_many:目录,:通过=>:位置.
• 目录has_many:people,:through =>:position.
• Person和Directory has_many:position.
• 除了具有id,person_id和directory_id之外,Position模型还具有一个或多个附加字段(例如,标题).

我希望能够做的是每次我将一个人添加到Directory.people集合时,将数据添加到连接模型,例如标题字段.通常的<<运营商不会削减它.Id est:

directory = Directory.last     # Let's assume that retrieves a Directory object
person = Person.last           # Let's assume that retrieves a Person object
directory.people << person

这会将人员添加到Directory对象的people集合中,但不允许我有机会将数据分配给连接模型.因此,在对该网站进行了大量研究后,我发现了另一种方法将Person添加到people集合中,并将数据添加到链接Person和Directory的Position,id:

directory = Directory.last     # Let's assume that retrieves a Directory object
person = Person.last           # Let's assume that retrieves a Person object
position = person.positions.build(:directory_id => directory.id, :title => "Administrative Assistant") 
position.save

这很麻烦.同样繁琐的方式是:

directory = Directory.last     # Let's assume that retrieves a Directory object
person = Person.last           # Let's assume that retrieves a Person object
position = Position.new(directory_id: directory.id, person_id: person.id, title: "Administrative Assistant")

再次,似乎是错误的,因为我希望能够强调Person和Directory之间的关系,我相信这是使用has_many的原因:通过适当的.

我希望能够做的是使用<<运算符,并传递其他数据,例如:

directory = Directory.last # Let's assume that retrieves a Directory object
person = Person.last # Let's assume that retrieves a Person object
directory.people << person, :position => {:title => "Administrative Assistant"}

我在has_many中重载了<<运算符:通过声明,如下所示:

has_many :people, :through => :positions do
  def << *args
    arg = args.first
    if arg.is_a?(Person)
      self.push([arg]) 
    elsif arg.is_a?(Hash)
      # Don't know what to do in here (see below)
    else
      raise "Invalid Value" # There's a better error to raise here, but good enough for now.
    end
  end
end

获得这个工作的好处是它在语法上很好地工作,并允许我简洁地将数据分配给连接对象(位置),同时将Person添加到Directory对象的people集合.

但我无法使其工作,因为我需要能够访问<<运算符左侧的人员集合属性的Directory对象,以便构建一个位置并将其保存到数据库中.

所以,我的问题是:

1. 有没有办法从对象的属性访问对象？
2. 在替代方案中,是否有另一种方法来重载<<运算符,以便在向集合添加一个对象时可以轻松地将数据分配给连接模型？

非常感谢您的帮助和深思熟虑的回复.我已经在这半天被黑客攻击无济于事.

回答 感谢回答这个问题的PinnyM,我能够提出这个实现:

module AddToPeopleAndPositionExtension
  def << *args
    arg = args.first
      if arg.is_a?(Person)
        self.push([arg]) 
        return self
      elsif arg.is_a?(Hash)
        directory = proxy_association.owner
        person = arg[:person]
        position = person.positions.build(:directory_id => directory.id, :title => arg[:position][:title]) 
        position.save
      else
        raise "Invalid Value"
      end
  end
end

class Directory < ActiveRecord::Base  
  # Relationships
  has_many :positions
  has_many :people, :through => :positions, :extend => AddToPeopleAndPositionExtension
end

如果我不关心连接模型上发生了什么,这允许我以标准方式调用<<运算符,例如:

directory = Directory.last     # Let's assume that retrieves a Directory object
person = Person.last           # Let's assume that retrieves a Person object
directory.people << person

而且,我也可以通过指定连接模型的属性来调用它,如:

directory = Directory.last     # Let's assume that retrieves a Directory object
person = Person.last           # Let's assume that retrieves a Person object
directory.people << {:person => person, :position => {:title => "Administrative Assistant"}}

Answer 1

您可以使用proxy_association块内的帮助程序来获取关联并proxy_association.owner获取Directory对象本身.请参阅此处以获取更多相关信息.