小编Bab*_*nov的帖子

例如,有一些模型

class Model_1 < ActiveRecord::Base
   has_many :images, :as => :imageable
end

class Model_2 < ActiveRecord::Base
   # doesn't have has_many association
end
...
class Image < ActiveRecord::Base
    belongs_to :imageable, :polymorphic => true
end

如何检查该模型是否具有has_many关联？像这样的东西

class ActiveRecord::Base
    def self.has_many_association_exists?(:association)
        ...
    end
end

它可以这样使用

Model_1.has_many_association_exists?(:images) # true
Model_2.has_many_association_exists?(:images) # false

提前致谢

有没有办法通过键从哈希中删除并返回删除的值.即此代码:

var a = attributes['a']
delete attributes['a']

单行.像Ruby一样的Smth delete:

a = attributes.delete(:a)