ruby-on-rails-3 – 多个日期范围内的Rails 3查询

发布时间：2020-12-17 02:35:45 所属栏目：百科来源：网络整理

导读：假设我们有一些日期范围,例如： ranges = [ [(12.months.ago)..(8.months.ago)],[(7.months.ago)..(6.months.ago)],[(5.months.ago)..(4.months.ago)],[(3.months.ago)..(2.months.ago)],[(1.month.ago)..(15.days.ago)] ] 和一个Post模型：created_at属性.

假设我们有一些日期范围,例如：

ranges = [
          [(12.months.ago)..(8.months.ago)],[(7.months.ago)..(6.months.ago)],[(5.months.ago)..(4.months.ago)],[(3.months.ago)..(2.months.ago)],[(1.month.ago)..(15.days.ago)]
         ]

和一个Post模型：created_at属性.

我想查找created_at值在此范围内的帖子,因此我们的目标是创建一个类似的查询：

SELECT * FROM posts WHERE created_at 
    BETWEEN '2011-04-06' AND '2011-08-06' OR
    BETWEEN '2011-09-06' AND '2011-10-06' OR
    BETWEEN '2011-11-06' AND '2011-12-06' OR
    BETWEEN '2012-01-06' AND '2012-02-06' OR
    BETWEEN '2012-02-06' AND '2012-03-23';

如果您只有一个这样的范围：

range = (12.months.ago)..(8.months.ago)

我们可以做这个查询：

Post.where(:created_at => range)

和查询应该是：

SELECT * FROM posts WHERE created_at 
    BETWEEN '2011-04-06' AND '2011-08-06';

有没有办法使用像这个Post.where(：created_at =>范围)这样的符号来进行此查询？

构建此查询的正确方法是什么？

谢谢

解决方法

对于帕伦来说,它有点激进,但准备潜入这个兔子洞

ranges = [
          ((12.months.ago)..(8.months.ago)),((7.months.ago)..(6.months.ago)),((5.months.ago)..(4.months.ago)),((3.months.ago)..(2.months.ago)),((1.month.ago)..(15.days.ago))
         ]
table = Post.arel_table
query = ranges.inject(table) do |sum,range|
  condition = table[:created_at].in(range)
  sum.class == Arel::Table ? condition : sum.or(condition)
end

然后,query.to_sql应该相等

(((("sessions"."created_at" BETWEEN '2011-06-05 12:23:32.442238' AND '2011-10-05 12:23:32.442575' OR "sessions"."created_at" BETWEEN '2011-11-05 12:23:32.442772' AND '2011-12-05 12:23:32.442926') OR "sessions"."created_at" BETWEEN '2012-01-05 12:23:32.443112' AND '2012-02-05 12:23:32.443266') OR "sessions"."created_at" BETWEEN '2012-03-05 12:23:32.443449' AND '2012-04-05 12:23:32.443598') OR "sessions"."created_at" BETWEEN '2012-05-05 12:23:32.443783' AND '2012-05-21 12:23:32.443938')

你应该能够做Post.where(查询)

编辑

你也可以这样做：

range_conditions = ranges.map{|r| table[:created_at].in(r)}
query = range_conditions.inject(range_conditions.shift,&:or)

保持一点简洁

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!