Rails uniq公共活动

Question

t = PublicActivity::Activity.arel_table

@activities = PublicActivity::Activity.where(
    (t[:trackable_type].eq("Lesson").and(t[:trackable_id].in(@my_lessons_ids)))
    .or(t[:trackable_type].eq("Post").and(t[:trackable_id].in(@my_posts_ids)))
    .or(t[:trackable_type].eq("WallPost").and(t[:trackable_id].in(@my_wallposts_ids)))
    .or(t[:trackable_type].eq("Comment").and(t[:trackable_id].in(@my_comments_ids)))
    .or(t[:trackable_type].eq("Course").and(t[:trackable_id].in(@my_courses_ids)))
    .or(t[:trackable_type].eq("Group").and(t[:trackable_id].in(@my_groups_ids)))
).order("id DESC").uniq{|a| "#{a.trackable_type}-#{a.trackable_id}"}

在我的数据库中，我有“Trackable_type”+“trackable_id”的重复条目，因为如果用户多次点击“更新”，我会收到很多条目。 所以，我只想得到其中一个。 我试过了 .uniq{|a| "#{a.trackable_type}-#{a.trackable_id}"}

但没有任何反应。

返回SQL QUERY：

  

“SELECT DISTINCT”活动\“。* FROM \”activities \“WHERE   （（（（（\“activities \”。\“trackable_type \”='Lesson'AND   \“活动\”。\“trackable_id \”IN（11,39,40,16,5,3,12,9,13，   19,18,37,15,23,24,29,20,10,25,26,27,17,28,22,21,30，   33,35,34,36,32,31）或“活动”。\“trackable_type \”='发布'   AND \“activities \”。\“trackable_id \”IN（50,49,48,47,46,45,44，   43,42,41,40,37,36,35,34,33,32,31,30,29,28,27,26,25，   24,23,22,21,20,19,18,17,14,13,12,10,5））OR   \“活动\”。\“trackable_type \”='WallPost'AND   \“活动\”。\“trackable_id \”IN（158,157,155,154,153,152,151，   132,131,130,129,128,127,126,125,124,119,118,117,116,115，   114,113,111,110,109,108,107,106,105,104,103,102,101,100，   99,98,93,92,91,90,87,85,84,83,82,81,80,79,78,77,76，   75,74,73,72,71,70,69,68,67,66,65,64,63,62,61,60,59，   58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42，   41,39,38,37,36,35,34,33,31,30,29,28,27,26,25,24,22，   20,19,17,16,15,14,13,10,7,6,5,4））或   \“活动\”。\“trackable_type \”='评论'和   \“活动\”。\“trackable_id \”IN（100,99,98,95,83,82,81,79，   78,71,70,69,68,67,65,63,62,61,60,59,58,57,56,55,52，   51,50,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35，   34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18，   17,16,15,14））或“活动”。\“trackable_type \”='课程'和   \“活动\”。\“trackable_id \”IN（8,1,5,7））或   \“活动\”。\“trackable_type \”='组'和   \“活动\”。\“trackable_id \”IN（14,11,4,5,6,3,2,1））令   BY id DESC“

更新

如果我尝试：

@activities = PublicActivity::Activity.select("distinct trackable_type, trackable_id").where(
        (t[:trackable_type].eq("Lesson").and(t[:trackable_id].in(@my_lessons_ids)))
        .or(t[:trackable_type].eq("Post").and(t[:trackable_id].in(@my_posts_ids)))
        .or(t[:trackable_type].eq("WallPost").and(t[:trackable_id].in(@my_wallposts_ids)))
        .or(t[:trackable_type].eq("Comment").and(t[:trackable_id].in(@my_comments_ids)))
        .or(t[:trackable_type].eq("Course").and(t[:trackable_id].in(@my_courses_ids)))
        .or(t[:trackable_type].eq("Group").and(t[:trackable_id].in(@my_groups_ids)))
    ).order("id DESC")

我明白了：

更新2

如果我尝试

@activities = PublicActivity::Activity.select("DISTINCT ON(trackable_type, trackable_id) *")

我得到了

PG::SyntaxError: ERROR: syntax error at or near "ON" LINE 1: SELECT COUNT(DISTINCT ON(trackable_type, trackable_id) *) FR... ^ : SELECT COUNT(DISTINCT ON(trackable_type, trackable_id) *) FROM "activities"

Answer 1

没有arel的查询将是：

PublicActivity::Activity.select("DISTINCT ON(trackable_type, trackable_id) *")
              .where("(trackable_type = ? and trackable_id IN (?))
                      or (trackable_type = ? and trackable_id IN (?))",
                      "Lesson", @my_lessons_ids,
                      "Post", @my_post_ids)