ruby - 嵌套散列迭代：如何在散列中的（（散列数组）上迭代合并）

Question

我正在努力按照标题所说的去做。这是我的代码：

school.each { |x| school[:students][x].merge!(semester:"Summer") }

我想我将问题定位到上面的“[x]”。如果我替换一个数组位置，例如“[2]”，它可以正常工作。如何使迭代工作？

如果以上信息还不够，或者您想提供更好的解决方案，请参阅下面的详细信息。谢谢！

---

我得到的错误信息：

file.rb:31:in []': no implicit conversion of Array into Integer (TypeError) from file.rb:31:inblock in ' from file.rb:31:in each' from file.rb:31:in'

更改前的嵌套哈希如下：

school = { 
  :name => "Happy Funtime School",
  :location => "NYC",
  :instructors => [ 
    {:name=>"Blake", :subject=>"being awesome" },
    {:name=>"Ashley", :subject=>"being better than blake"},
    {:name=>"Jeff", :subject=>"karaoke"}
  ],
  :students => [ 
    {:name => "Marissa", :grade => "B"},
    {:name=>"Billy", :grade => "F"},
    {:name => "Frank", :grade => "A"},
    {:name => "Sophie", :grade => "C"}
  ]
}

我正在尝试将 :semester=>"Summer" 附加到最后四个哈希中的每一个。这是我想要的：

# ...preceding code is the same. Changed code below...
  :students => [ 
    {:name => "Marissa", :grade => "B", :semester => "Summer"},
    {:name=>"Billy", :grade => "F", :semester => "Summer"},
    {:name => "Frank", :grade => "A", :semester => "Summer"},
    {:name => "Sophie", :grade => "C", :semester => "Summer"}
  ]
}

Answer 1

只需遍历学生：

school[:students].each { |student| student[:semester] = "Summer" }

或者，使用合并：

school[:students].each { |student| student.merge!(semester: "Summer") }

Answer 2

我会使用以下方法Hash#store：

require 'awesome_print'

school = {
                 :name => "Happy Funtime School",
             :location => "NYC",
          :instructors => [
                    {
                                 :name => "Blake",
                              :subject => "being awesome"
                    },
                    {
                                 :name => "Ashley",
                              :subject => "being better than blake"
                    },
                    {
                                 :name => "Jeff",
                              :subject => "karaoke"
                    }
          ],
             :students => [
                    {
                               :name => "Marissa",
                              :grade => "B"
                    },
                    {
                               :name => "Billy",
                              :grade => "F"
                    },
                    {
                               :name => "Frank",
                              :grade => "A"
                    },
                    {
                               :name => "Sophie",
                              :grade => "C"
                    }
          ]
}

school[:students].each{|h| h.store(:semester ,"Summer")}
ap school,:index => false,:indent => 10

输出

{
                 :name => "Happy Funtime School",
             :location => "NYC",
          :instructors => [
                    {
                                 :name => "Blake",
                              :subject => "being awesome"
                    },
                    {
                                 :name => "Ashley",
                              :subject => "being better than blake"
                    },
                    {
                                 :name => "Jeff",
                              :subject => "karaoke"
                    }
          ],
             :students => [
                    {
                                  :name => "Marissa",
                                 :grade => "B",
                              :semester => "Summer"
                    },
                    {
                                  :name => "Billy",
                                 :grade => "F",
                              :semester => "Summer"
                    },
                    {
                                  :name => "Frank",
                                 :grade => "A",
                              :semester => "Summer"
                    },
                    {
                                  :name => "Sophie",
                                 :grade => "C",
                              :semester => "Summer"
                    }
          ]
}

Answer 3

问题是当你做 array.each {|x| do something}, x 实际上是指数组中的每个元素。

例如，在循环的第一次迭代中，

x = {:name => "Marissa", :grade => "B"}

所以你真正在做的是试图参考：

school[:student][{:name => "Marissa", :grade => "B"}]

哪个行不通

您可以做的是创建一个 for 循环来跟踪索引。

for i in 0 ... school[:student].count
    school[:students][i].merge!(semester:"Summer")
end

编辑： Stefan 的解决方案比我的要好得多，但我会留下来说明你哪里出错了。