Rails分組並處理哈希數組

Question

我有一系列的紅寶石哈希值。 結構如下：

[ {
  :question_id => 1
  :topic_id    => 2
  }
  {
  :question_id => 1
  :topic_id    => 3
  }
  {
  :question_id => 2
  :topic_id    => 1
  }
  ...
]

我想按question_id進行分組，然后進一步將topic_id串聯topic_id ，使其看起來像：

  [ {
      :question_id => 1
      :topic_id    => 2,3
      }
      {
      :question_id => 2
      :topic_id    => 1
      }
      ...
    ]

group_by允許我對topic_id進行分組但不能串聯。

result.group_by{|h| h[:question_id]}.map do |question_id, hash|
  { question_id: question_id, topic_id: hash.map{|h| h[:topic_id].to_s + ","}}
end

什么是干凈的紅寶石方法？

Answer 1

替換hash.map{|h| h[:topic_id].to_s + ","} hash.map{|h| h[:topic_id].to_s + ","}和hash.map{|h| h[:topic_id]}.join(',') hash.map{|h| h[:topic_id]}.join(',')

result = [ { :question_id => 1, :topic_id    => 2 },{:question_id => 1, :topic_id    => 3 },{  :question_id => 2, :topic_id    => 11 }]
result.group_by{|h| h[:question_id]}.map{ |q_id, hashes_array|  {:question_id => q_id, :topic_id => hashes_array.map{|hash| hash[:topic_id]}.join(',') } }

希望您能得到想要的結果。

Answer 2

僅刪除.to_s + ","位，您的代碼似乎已經正確了嗎？

result = [{:question_id => 1, :topic_id => 2}, {:question_id => 1, :topic_id => 3}, {:question_id => 2, :topic_id => 1}]

result.group_by{|h| h[:question_id]}.map { |question_id, hash| { question_id: question_id, topic_id: hash.map{|h| h[:topic_id]}} }
=> [{:question_id=>1, :topic_id=>[2, 3]}, {:question_id=>2, :topic_id=>[1]}]

這似乎符合您的需求？ 還是我誤會了你的問題？