Question

正如您在下面的当前代码中所看到的，我根据属性recordable_id找到了重复项。我需要做的是根据四个匹配的属性找到副本：user_id，recordable_type，hero_type，recordable_id。我该如何修改代码？

heroes = User.heroes

for hero in heroes
  hero_statuses = hero.hero_statuses

  seen = []

  hero_statuses.sort! {|a,b| a.created_at <=> b.created_at } # sort by created_at
  hero_statuses.each do |hero_status|
    if seen.map(&:recordable_id).include? hero_status.recordable_id # check if the id has been seen already
      hero_status.revoke
    else
      seen << hero_status # if not, add it to the seen array
    end
  end
end

Answer 1

试试这个：

HeroStatus.all(:group =>  "user_id, recordable_type, hero_type, recordable_id",
               :having => "count(*) > 1").each do |status|
  status.revoke 
end

编辑2 要撤消所有最新的重复条目，请执行以下操作：

HeroStatus.all(:joins => "(
     SELECT   user_id, recordable_type, hero_type, 
              recordable_id, MIN(created_at) AS created_at
     FROM     hero_statuses
     GROUP BY user_id, recordable_type, hero_type, recordable_id
     HAVING   COUNT(*) > 1
   ) AS A ON A.user_id         = hero_statuses.user_id         AND 
             A.recordable_type = hero_statuses.recordable_type AND
             A.hero_type       = hero_statuses.hero_type       AND
             A.recordable_id   = hero_statuses.recordable_id   AND
             A.created_at      < hero_statuses.created_
").each do |status|
  status.revoke 
end

Answer 2

使用直接Ruby（不是SQL服务器）：

heroes = User.heroes

for hero in heroes
  hero_statuses = hero.hero_statuses

  seen = {}

  hero_statuses.sort_by!(&:created_at)
  hero_statuses.each do |status|
    key = [status.user_id, status.recordable_type, status.hero_type, status.recordable_id]
    if seen.has_key?(key)
      status.revoke
    else
      seen[key] = status # if not, add it to the seen array
    end
  end

  remaining = seen.values
end

对于查找，请始终使用Hash（或Set，但在此我认为保留已保留的状态会很好。

注意：我使用的是sort_by!，但这是1.9.2的新功能，因此请使用sort_by（或require "backports"）

使用Array.map删除具有相同属性的“重复对象”

2 个答案: