如何在联接表上/与联接表一起写条件？

Question

[票务和帐户有两种模式。帐户中有很多票。我正在尝试为每个帐户获取最后创建的票证。

accounts = Account.where(:deleted => false).pluck(:id)    
tickets = Ticket
    .left_outer_joins(:admin)
    .left_outer_joins(:account)
    .where(:account_id => accounts)
    .where("ticket_status_id != 6").order(created_at: :desc)

  ticket_ids = Array.new
  accounts.each do |account|
    ticket = tickets.where(:account_id => account).order(created_at: :desc).limit(1).first
    if !ticket.blank?
      ticket_ids.push(ticket.id)
    end
  end

  @tickets = tickets.where(:id => ticket_ids).order(created_at: :desc)

上面的代码有效，@ tickets包含预期的输出。但是问题是上面的代码花费了很多时间。有什么办法可以在获取查询本身中完成所有这些工作？还是有什么方法可以对其进行优化？

Answer 1

ticket_ids = Ticket.order(created_at: :desc).group_by(&:account_id).values
@tickets = Ticket.where(id: ticket_ids)