数组的未定义方法？

Question

所以我有这个数据结构:

+[#<Folder id: 1, name: "mollitia", parent_id: nil, user_id: 1, created_at: "2014-06-27 16:00:59", updated_at: "2014-06-27 16:00:59">,
+ #<Folder id: 2, name: "porro", parent_id: 1, user_id: 1, created_at: "2014-06-27 16:00:59", updated_at: "2014-06-27 16:00:59">, 
+ #<Folder id: 3, name: "omnis", parent_id: 2, user_id: 1, created_at: "2014-06-27 16:00:59", updated_at: "2014-06-27 16:00:59">]

self.ancestors 我可以把它的名字归还吗？

def pwd
    self.ancestors.pluck(:name)
end

以上结果

undefined method `pluck' for #<Array:0x007ff4da780290>

更新

令人敬畏的结构打印:

[
    [0] #<Folder:0x007fd2946a5f18> {
                :id => 3,
              :name => "blanditiis",
         :parent_id => 2,
           :user_id => 1,
        :created_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00,
        :updated_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00
    },
    [1] #<Folder:0x007fd2946ad1c8> {
                :id => 2,
              :name => "neque",
         :parent_id => 1,
           :user_id => 1,
        :created_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00,
        :updated_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00
    },
    [2] #<Folder:0x007fd2946b80c8> {
                :id => 1,
              :name => "ut",
         :parent_id => nil,
           :user_id => 1,
        :created_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00,
        :updated_at => Fri, 27 Jun 2014 18:04:02 UTC +00:00
    }
]

Answer 1

pluck与rails一起使用以更改与数据库的关联查询.它会从改变SELECT *到SELECT [attr]哪里[attr]是采摘的说法.因为它是一个数组,所以你不能使用它.你应该使用map红宝石中的常规旧版本.在你的情况下,它看起来像:

def pwd
  self.ancestors.map(&:name)
end