如何在ruby / rails中将多个参数传递给Proc？

Question

以下是给我的问题：

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

我认为这是因为我两次打电话给：reject_if，而不是100％确定。 但是，每当我取消注释photo_title reject_if行时，如果选择一个，我的图像就不会上传。 如果我注释掉那行，那就可以了。

如何将两个条件合并为一个reject_if条件？ 如果这样的话。

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
}

粗箭头参数实际上是一个Hash，大括号实际上是Ruby在背后添加的。 哈希不允许重复的键，因此第二个:reject_if值将覆盖第一个，您最终会得到以下结果：

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

但是，您可以将两个条件组合在一个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

Answer 2

尝试这个

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