discourse/app/models/topic_featured_users.rb

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class TopicFeaturedUsers
attr_reader :topic
def initialize(topic)
@topic = topic
end
def self.count
4
end
# Chooses which topic users to feature
def choose(args={})
clear
update keys(args)
update_participant_count
topic.save
end
def user_ids
[topic.featured_user1_id,
topic.featured_user2_id,
topic.featured_user3_id,
topic.featured_user4_id].uniq.compact
end
def self.ensure_consistency!
sql = <<SQL
WITH cte as (
SELECT
t.id, p.user_id,
ROW_NUMBER() OVER(PARTITION BY t.id ORDER BY COUNT(*) 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.user_id <> t.user_id AND
p.user_id <> t.last_post_user_id
GROUP BY t.id, p.user_id
)
UPDATE topics tt
SET
featured_user1_id = featured_user1,
featured_user2_id = featured_user2,
featured_user3_id = featured_user3,
featured_user4_id = featured_user4
FROM (
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 cte as c
WHERE c.rank <= 4
GROUP BY c.id
) x
WHERE x.id = tt.id AND
(
COALESCE(featured_user1_id,-99) <> COALESCE(featured_user1,-99) OR
COALESCE(featured_user2_id,-99) <> COALESCE(featured_user2,-99) OR
COALESCE(featured_user3_id,-99) <> COALESCE(featured_user3,-99) OR
COALESCE(featured_user4_id,-99) <> COALESCE(featured_user4,-99)
)
SQL
Topic.exec_sql(sql)
end
private
def keys(args)
# Don't include the OP or the last poster
to_feature = topic.posts.where('user_id NOT IN (?, ?)', topic.user_id, topic.last_post_user_id)
# Exclude a given post if supplied (in the case of deletes)
to_feature = to_feature.where("id <> ?", args[:except_post_id]) if args[:except_post_id].present?
# Assign the featured_user{x} columns
to_feature.group(:user_id).order('count_all desc').limit(TopicFeaturedUsers.count).count.keys
end
def clear
TopicFeaturedUsers.count.times do |i|
topic.send("featured_user#{i+1}_id=", nil)
end
end
def update(user_keys)
user_keys.each_with_index do |user_id, i|
topic.send("featured_user#{i+1}_id=", user_id)
end
end
def update_participant_count
topic.participant_count = topic.posts.count('distinct user_id')
end
end