Class: TopicFeaturedUsers

Inherits:
Object
  • Object
show all
Defined in:
app/models/topic_featured_users.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(topic) ⇒ TopicFeaturedUsers

Returns a new instance of TopicFeaturedUsers.



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# File 'app/models/topic_featured_users.rb', line 6

def initialize(topic)
  @topic = topic
end

Instance Attribute Details

#topic ⇒ Object (readonly)

Returns the value of attribute topic.



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# File 'app/models/topic_featured_users.rb', line 4

def topic
  @topic
end

Class Method Details

.count ⇒ Object 



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# File 'app/models/topic_featured_users.rb', line 10

def self.count
  4
end

.ensure_consistency!(topic_id = nil) ⇒ Object 



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# File 'app/models/topic_featured_users.rb', line 29

def self.ensure_consistency!(topic_id = nil)
  filter = "#{"AND t.id = #{topic_id.to_i}" if topic_id}"
  filter2 = "#{"AND tt.id = #{topic_id.to_i}" if topic_id}"

  sql = <<SQL

WITH cte as (
  SELECT
      t.id,
      p.user_id,
      MAX(p.created_at) last_post_date,
      ROW_NUMBER() OVER(PARTITION BY t.id ORDER BY COUNT(*) DESC, MAX(p.created_at) DESC) as rank
  FROM topics t
  JOIN posts p ON p.topic_id = t.id
  WHERE p.deleted_at IS NULL AND
        NOT p.hidden AND
        p.post_type in (#{Topic.visible_post_types.join(",")}) AND
        p.user_id <> t.user_id AND
        p.user_id <> t.last_post_user_id
        #{filter}
  GROUP BY t.id, p.user_id
),

cte2 as (
SELECT id, user_id, ROW_NUMBER() OVER(PARTITION BY id ORDER BY last_post_date ASC) as rank
FROM cte
WHERE rank <= #{count}
)

UPDATE topics tt
SET
featured_user1_id = x.featured_user1,
featured_user2_id = x.featured_user2,
featured_user3_id = x.featured_user3,
featured_user4_id = x.featured_user4
FROM topics AS tt2
LEFT OUTER JOIN (
SELECT
    c.id,
    MAX(case when c.rank = 1 then c.user_id end) featured_user1,
    MAX(case when c.rank = 2 then c.user_id end) featured_user2,
    MAX(case when c.rank = 3 then c.user_id end) featured_user3,
    MAX(case when c.rank = 4 then c.user_id end) featured_user4
FROM cte2 as c
GROUP BY c.id
) x ON x.id = tt2.id
WHERE tt.id = tt2.id AND
(
COALESCE(tt.featured_user1_id,-99) <> COALESCE(x.featured_user1,-99) OR
COALESCE(tt.featured_user2_id,-99) <> COALESCE(x.featured_user2,-99) OR
COALESCE(tt.featured_user3_id,-99) <> COALESCE(x.featured_user3,-99) OR
COALESCE(tt.featured_user4_id,-99) <> COALESCE(x.featured_user4,-99)
)
#{filter2}
SQL

  DB.exec(sql)
end

Instance Method Details

#choose(args = {}) ⇒ Object

Chooses which topic users to feature



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# File 'app/models/topic_featured_users.rb', line 15

def choose(args = {})
  self.class.ensure_consistency!(topic.id.to_i)
  update_participant_count
end

#user_ids ⇒ Object 



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# File 'app/models/topic_featured_users.rb', line 20

def user_ids
  [
    topic.featured_user1_id,
    topic.featured_user2_id,
    topic.featured_user3_id,
    topic.featured_user4_id,
  ].uniq.compact
end