我有一个关系通知的站点模型。该网站每天都有几个通知。我尝试计算几天的通知总和,并希望按此总和对网站进行排序。
class Site
has_many :notifications
scope :sort_by_notifications_between_dates_asc, -> (start_date, end_date) { left_joins(:notifications).merge(Notification.between_dates(start_date, end_date)).order(Arel.sql("count(notifications.*) asc")) }
scope :sort_by_notifications_between_dates_desc, -> (start_date, end_date) { left_joins(:notifications).merge(Notification.between_dates(start_date, end_date)).order(Arel.sql("count(notifications.*) desc")) }
end
class Notification
belongs_to :site
scope :between_dates, -> (start_date, end_date) {where(self.arel_table[:created_at].gteq(start_date.at_beginning_of_day).and(self.arel_table[:created_at].lteq(end_date.at_end_of_day)))}
end
ransack可以创建排序范围,但我还没有找到将参数(start_date和end_date)传递给此范围的方法。
= sort_link(@q, :notifications_between_dates, t('.notifications_between_dates'), default_order: :desc)
我不需要按日期过滤网站。我需要按照一段时间内的通知总和对网站进行排序。这甚至可能吗?
我找到了一半的解决方案。我用参数创建了ransacker
ransacker :notifications_between_dates, args: [:parent, :ransacker_args] do |parent, args|
start_date, end_date = args
query = <<-SQL
COALESCE(
(SELECT COUNT(notifications.*)
FROM notifications
WHERE notifications.site_id = sites.id
AND notifications.created_at >= '#{start_date}'
AND notifications.created_at <= '#{end_date}'
GROUP BY notifications.site_id)
,0)
SQL
Arel.sql(query)
end
然后我们可以这种方式对记录进行排序
q = Site.ransack(sorts: [{name: :notifications_between_dates,
dir: 'asc',
ransacker_args: [Time.now-20.days,Time.now]}])
但看起来sort_link助手不支持通过s参数中的GET请求传递ransacker_args。