Module: Thredded::UserTopicReadStateCommon::ClassMethods

Defined in:
app/models/concerns/thredded/user_topic_read_state_common.rb

Instance Method Summary collapse

Instance Method Details

#read_on_first_post!(user, topic) ⇒ Object 



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# File 'app/models/concerns/thredded/user_topic_read_state_common.rb', line 37

def read_on_first_post!(user, topic)
  create!(user: user, postable: topic, read_at: Time.zone.now)
end

#topic_class ⇒ Object 



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# File 'app/models/concerns/thredded/user_topic_read_state_common.rb', line 92

def topic_class
  reflect_on_association(:postable).klass
end

#touch!(user_id, topic_id, post) ⇒ Object

Parameters:



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# File 'app/models/concerns/thredded/user_topic_read_state_common.rb', line 28

def touch!(user_id, topic_id, post)
  # TODO: Switch to upsert once Travis supports PostgreSQL 9.5.
  # Travis issue: https://github.com/travis-ci/travis-ci/issues/4264
  # Upsert gem: https://github.com/seamusabshere/upsert
  state = find_or_initialize_by(user_id: user_id, postable_id: topic_id)
  return unless !state.read_at? || state.read_at < post.created_at
  state.update!(read_at: post.created_at)
end

#with_page_info(posts_per_page: topic_class.default_per_page, posts_scope: post_class.all) ⇒ Object

Adds first_unread_post_page and last_read_post_page columns onto the scope. Skips the records that have no read posts.



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# File 'app/models/concerns/thredded/user_topic_read_state_common.rb', line 43

def with_page_info( # rubocop:disable Metrics/MethodLength
  posts_per_page: topic_class.default_per_page, posts_scope: post_class.all
)
  states = arel_table
  self_relation = is_a?(ActiveRecord::Relation) ? self : all
  if self_relation == unscoped
    states_select_manager = states
  else
    # Using the relation here is redundant but massively improves performance.
    states_select_manager = Thredded::ArelCompat.new_arel_select_manager(
      Arel::Nodes::TableAlias.new(Thredded::ArelCompat.relation_to_arel(self_relation), table_name)
    )
  end
  read = if posts_scope == post_class.unscoped
           post_class.arel_table
         else
           posts_subquery = Thredded::ArelCompat.relation_to_arel(posts_scope)
           Arel::Nodes::TableAlias.new(posts_subquery, 'read_posts')
         end
  unread_topics = topic_class.arel_table
  page_info =
    states_select_manager
      .project(
        states[:id],
        Arel::Nodes::Case.new(unread_topics[:id].not_eq(nil))
          .when(Thredded::ArelCompat.true_value(self)).then(
            Arel::Nodes::Addition.new(
              Thredded::ArelCompat.integer_division(self, read[:id].count, posts_per_page), 1
            )
          ).else(nil)
          .as('first_unread_post_page'),
        Arel::Nodes::Addition.new(
          Thredded::ArelCompat.integer_division(self, read[:id].count, posts_per_page),
          Arel::Nodes::Case.new(Arel::Nodes::InfixOperation.new(:%, read[:id].count, posts_per_page))
            .when(0).then(0).else(1)
        ).as('last_read_post_page')
      )
      .join(read)
      .on(read[:postable_id].eq(states[:postable_id]).and(read[:created_at].lteq(states[:read_at])))
      .outer_join(unread_topics)
      .on(states[:postable_id].eq(unread_topics[:id]).and(unread_topics[:last_post_at].gt(states[:read_at])))
      .group(states[:id], unread_topics[:id])
      .as('id_and_page_info')

  # We use a subquery because selected fields must appear in the GROUP BY or be used in an aggregate function.
  select(states[Arel.star], page_info[:first_unread_post_page], page_info[:last_read_post_page])
    .joins(states.join(page_info).on(states[:id].eq(page_info[:id])).join_sources)
end