如何在ruby/rails中将多个参数传递给Proc？

Question

以下是给我一个问题:

accepts_nested_attributes_for :photo, 
:reject_if => proc { |attributes| attributes['image'].blank? }, 
:reject_if => proc { |attributes| attributes['photo_title'].blank? },
:allow_destroy => true

我想这是因为我打电话:reject_if两次,而不是100%肯定.但是当我取消注释photo_title reject_if行时,如果我选择一个,我的图像就不会上传.如果我评论该线路,那么它确实如此.

如何将两个条件组合成一个reject_if条件？如果这是有道理的.

亲切的问候

Answer 1

这个:

accepts_nested_attributes_for :photo, 
  :reject_if => proc { |attributes| attributes['image'].blank? }, 
  :reject_if => proc { |attributes| attributes['photo_title'].blank? },
  :allow_destroy => true

与此相同:

accepts_nested_attributes_for :photo, {
  :reject_if => proc { |attributes| attributes['image'].blank? }, 
  :reject_if => proc { |attributes| attributes['photo_title'].blank? },
  :allow_destroy => true
}

胖箭的参数实际上是一个哈希,大括号基本上是由Ruby背后添加的.Hash不允许重复键,所以第二个:reject_if值会覆盖第一个,最后你会得到:

accepts_nested_attributes_for :photo,
  :reject_if => proc { |attributes| attributes['photo_title'].blank? },
  :allow_destroy => true

您可以将一个条件组合在一个Proc中:

accepts_nested_attributes_for :photo,
  :reject_if => proc { |attributes| attributes['image'].blank? || attributes['photo_title'].blank? }, 
  :allow_destroy => true

您还可以使用单独的方法:

accepts_nested_attributes_for :photo,
  :reject_if => :not_all_there,
  :allow_destroy => true

def not_all_there(attributes)
  attributes['image'].blank? || attributes['photo_title'].blank?
end