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

我认为这是因为我打电话：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。如果我对该行进行评论，那么就可以了。

如何将两个条件合并为一个reject_if条件？如果这是有道理的。

亲切的问候

Answer 1

此：

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
}

fat-arrow参数实际上是一个Hash，大括号基本上是由Ruby背后添加的。哈希不允许重复键，因此第二个:reject_if值会覆盖第一个，最后你会得到这个：

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

您也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

Answer 2

试试这个

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

如何在ruby / rails中将多个参数传递给Proc？

2 个答案: