module ActiveRecord
# = Active Record Counter Cache
module CounterCache
extend ActiveSupport::Concern
module ClassMethods
# Resets one or more counter caches to their correct value using an SQL
# count query. This is useful when adding new counter caches, or if the
# counter has been corrupted or modified directly by SQL.
#
# ==== Parameters
#
# * +id+ - The id of the object you wish to reset a counter on.
# * +counters+ - One or more association counters to reset. Association name or counter name can be given.
# * :touch - Touch timestamp columns when updating.
# Pass +true+ to touch +updated_at+ and/or +updated_on+. Pass a symbol to
# touch that column or an array of symbols to touch just those ones.
#
# ==== Examples
#
# # For the Post with id #1, reset the comments_count
# Post.reset_counters(1, :comments)
#
# # Like above, but also touch the +updated_at+ and/or +updated_on+
# # attributes.
# Post.reset_counters(1, :comments, touch: true)
def reset_counters(id, *counters, touch: nil)
object = find(id)
counters.each do |counter_association|
has_many_association = _reflect_on_association(counter_association)
unless has_many_association
has_many = reflect_on_all_associations(:has_many)
has_many_association = has_many.find { |association| association.counter_cache_column && association.counter_cache_column.to_sym == counter_association.to_sym }
counter_association = has_many_association.plural_name if has_many_association
end
raise ArgumentError, "'#{name}' has no association called '#{counter_association}'" unless has_many_association
if has_many_association.is_a? ActiveRecord::Reflection::ThroughReflection
has_many_association = has_many_association.through_reflection
end
foreign_key = has_many_association.foreign_key.to_s
child_class = has_many_association.klass
reflection = child_class._reflections.values.find { |e| e.belongs_to? && e.foreign_key.to_s == foreign_key && e.options[:counter_cache].present? }
counter_name = reflection.counter_cache_column
updates = { counter_name.to_sym => object.send(counter_association).count(:all) }
updates.merge!(touch_updates(touch)) if touch
unscoped.where(primary_key => object.id).update_all(updates)
end
return true
end
# A generic "counter updater" implementation, intended primarily to be
# used by #increment_counter and #decrement_counter, but which may also
# be useful on its own. It simply does a direct SQL update for the record
# with the given ID, altering the given hash of counters by the amount
# given by the corresponding value:
#
# ==== Parameters
#
# * +id+ - The id of the object you wish to update a counter on or an array of ids.
# * +counters+ - A Hash containing the names of the fields
# to update as keys and the amount to update the field by as values.
# * :touch option - Touch timestamp columns when updating.
# Pass +true+ to touch +updated_at+ and/or +updated_on+. Pass a symbol to
# touch that column or an array of symbols to touch just those ones.
#
# ==== Examples
#
# # For the Post with id of 5, decrement the comment_count by 1, and
# # increment the action_count by 1
# Post.update_counters 5, comment_count: -1, action_count: 1
# # Executes the following SQL:
# # UPDATE posts
# # SET comment_count = COALESCE(comment_count, 0) - 1,
# # action_count = COALESCE(action_count, 0) + 1
# # WHERE id = 5
#
# # For the Posts with id of 10 and 15, increment the comment_count by 1
# Post.update_counters [10, 15], comment_count: 1
# # Executes the following SQL:
# # UPDATE posts
# # SET comment_count = COALESCE(comment_count, 0) + 1
# # WHERE id IN (10, 15)
#
# # For the Posts with id of 10 and 15, increment the comment_count by 1
# # and update the updated_at value for each counter.
# Post.update_counters [10, 15], comment_count: 1, touch: true
# # Executes the following SQL:
# # UPDATE posts
# # SET comment_count = COALESCE(comment_count, 0) + 1,
# # `updated_at` = '2016-10-13T09:59:23-05:00'
# # WHERE id IN (10, 15)
def update_counters(id, counters)
touch = counters.delete(:touch)
updates = counters.map do |counter_name, value|
operator = value < 0 ? "-" : "+"
quoted_column = connection.quote_column_name(counter_name)
"#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}"
end
if touch
touch_updates = touch_updates(touch)
updates << sanitize_sql_for_assignment(touch_updates) unless touch_updates.empty?
end
unscoped.where(primary_key => id).update_all updates.join(", ")
end
# Increment a numeric field by one, via a direct SQL update.
#
# This method is used primarily for maintaining counter_cache columns that are
# used to store aggregate values. For example, a +DiscussionBoard+ may cache
# posts_count and comments_count to avoid running an SQL query to calculate the
# number of posts and comments there are, each time it is displayed.
#
# ==== Parameters
#
# * +counter_name+ - The name of the field that should be incremented.
# * +id+ - The id of the object that should be incremented or an array of ids.
# * :touch - Touch timestamp columns when updating.
# Pass +true+ to touch +updated_at+ and/or +updated_on+. Pass a symbol to
# touch that column or an array of symbols to touch just those ones.
#
# ==== Examples
#
# # Increment the posts_count column for the record with an id of 5
# DiscussionBoard.increment_counter(:posts_count, 5)
#
# # Increment the posts_count column for the record with an id of 5
# # and update the updated_at value.
# DiscussionBoard.increment_counter(:posts_count, 5, touch: true)
def increment_counter(counter_name, id, touch: nil)
update_counters(id, counter_name => 1, touch: touch)
end
# Decrement a numeric field by one, via a direct SQL update.
#
# This works the same as #increment_counter but reduces the column value by
# 1 instead of increasing it.
#
# ==== Parameters
#
# * +counter_name+ - The name of the field that should be decremented.
# * +id+ - The id of the object that should be decremented or an array of ids.
# * :touch - Touch timestamp columns when updating.
# Pass +true+ to touch +updated_at+ and/or +updated_on+. Pass a symbol to
# touch that column or an array of symbols to touch just those ones.
#
# ==== Examples
#
# # Decrement the posts_count column for the record with an id of 5
# DiscussionBoard.decrement_counter(:posts_count, 5)
#
# # Decrement the posts_count column for the record with an id of 5
# # and update the updated_at value.
# DiscussionBoard.decrement_counter(:posts_count, 5, touch: true)
def decrement_counter(counter_name, id, touch: nil)
update_counters(id, counter_name => -1, touch: touch)
end
private
def touch_updates(touch)
touch = timestamp_attributes_for_update_in_model if touch == true
touch_time = current_time_from_proper_timezone
Array(touch).map { |column| [ column, touch_time ] }.to_h
end
end
private
def _create_record(*)
id = super
each_counter_cached_associations do |association|
if send(association.reflection.name)
association.increment_counters
@_after_create_counter_called = true
end
end
id
end
def destroy_row
affected_rows = super
if affected_rows > 0
each_counter_cached_associations do |association|
foreign_key = association.reflection.foreign_key.to_sym
unless destroyed_by_association && destroyed_by_association.foreign_key.to_sym == foreign_key
if send(association.reflection.name)
association.decrement_counters
end
end
end
end
affected_rows
end
def each_counter_cached_associations
_reflections.each do |name, reflection|
yield association(name.to_sym) if reflection.belongs_to? && reflection.counter_cache_column
end
end
end
end