ruby-on-rails - Rails/Ruby：将查询结果转换为多级哈希

Question

我有一个查询*，结果如下：

#<ActiveRecord::Relation [
    #<BookRank id: 2, book_id: 2, list_edition_id: 1, rank_world: 5, rank_europe: 1>,
    #<BookRank id: 3, book_id: 1, list_edition_id: 1, rank_world: 6, rank_europe: 2>,
    #<BookRank id: 8, book_id: 2, list_edition_id: 3, rank_world: 1, rank_europe: 1>,
    #<BookRank id: 9, book_id: 1, list_edition_id: 3, rank_world: 2, rank_europe: 2
]>

我想要得到的是这样的哈希：

{
    book_id => {
        list_edition_id => {
            "rank_world" => value,
            "rank_europe" => value
        }
    }
}

（最重要的是按最低 list_edition_id 的 rank_world 值对哈希进行排序，但这可能太复杂了。）

ranks_relation.group_by(&:book_id)给了我一个哈希值，其中book_ids是键，但是排名数据仍然在数组中：

{
    2 => [
            #<BookRank id: 2, book_id: 2, list_edition_id: 1, rank_world: 5, rank_europe: 1>,
            #<BookRank id: 8, book_id: 2, list_edition_id: 3, rank_world: 1, rank_europe: 1>
    ],
    1 => [
            #<BookRank id: 3, book_id: 1, list_edition_id: 1, rank_world: 6, rank_europe: 2>
            #<BookRank id: 9, book_id: 1, list_edition_id: 3, rank_world: 2, rank_europe: 2>
    ]
}

我应该如何进行？

*编辑：这是模型结构和查询。另一个用户要求它：

class Book < ActiveRecord::Base
  has_many :book_ranks, dependent: :destroy
end

class List < ActiveRecord::Base
  has_many :list_editions, dependent: :destroy
end

class ListEdition < ActiveRecord::Base
  belongs_to :list
  has_many :book_ranks, dependent: :destroy
end

class BookRank < ActiveRecord::Base
  belongs_to :book
  belongs_to :list_edition

  has_one :list, through: :list_edition
end

对于查询，我已经使用了两个具有相关 ID 的数组Book和ListEdition：

BookRank.where(:book_id => book_ids, :list_edition_id => list_edition_ids)

标签： ruby-on-railsrubyactiverecordruby-hash

Answer 1

尝试这个

record = your_record

hash = {}

record.each do |record|
  hash[record.book_id] ||= {}
  hash[record.book_id][record.list_edition_id] = {
    'rank_world' => record.rank_world,
    'rank_europe' => record.rank_europe
  }
end
# hash will then be {2=>{1=>{"rank_world"=>5, "rank_europe"=>1}, 3=>{"rank_world"=>1, "rank_europe"=>1}}, 1=>{1=>{"rank_world"=>6, "rank_europe"=>2}, 3=>{"rank_world"=>2, "rank_europe"=>2}}}

这将仅遍历记录一次。