lib/mongoid/relations/counter_cache.rb
# encoding: utf-8
module Mongoid
module Relations
module CounterCache
extend ActiveSupport::Concern
# Reset the given counter using the .count() query from the
# db. This method is usuful in case that a counter got
# corrupted, or a new counter was added to the collection.
#
# @example Reset the given counter cache
# post.reset_counters(:comments)
#
# @param [ Symbol, Array ] One or more counter caches to reset
#
# @since 4.0.0
def reset_counters(*counters)
self.class.reset_counters(self, *counters)
end
module ClassMethods
# Reset the given counter using the .count() query from the
# db. This method is usuful in case that a counter got
# corrupted, or a new counter was added to the collection.
#
# @example Reset the given counter cache
# Post.reset_counters('50e0edd97c71c17ea9000001', :comments)
#
# @param [ String ] The id of the object that will be reset.
# @param [ Symbol, Array ] One or more counter caches to reset
#
# @since 3.1.0
def reset_counters(id, *counters)
document = id.is_a?(Document) ? id : find(id)
counters.each do |name|
meta = reflect_on_association(name)
inverse = meta.klass.reflect_on_association(meta.inverse)
counter_name = inverse.counter_cache_column_name
document.update_attribute(counter_name, document.send(name).count)
end
end
# Update the given counters by the value factor. It uses the
# atomic $inc command.
#
# @example Add 5 to comments counter and remove 2 from likes
# counter.
# Post.update_counters('50e0edd97c71c17ea9000001',
# :comments_count => 5, :likes_count => -2)
#
# @param [ String ] The id of the object to update.
# @param [ Hash ] Key = counter_cache and Value = factor.
#
# @since 3.1.0
def update_counters(id, counters)
where(:_id => id).inc(counters)
end
# Increment the counter name from the entries that match the
# id by one. This method is used on associations callbacks
# when counter_cache is enabled
#
# @example Increment comments counter
# Post.increment_counter(:comments_count, '50e0edd97c71c17ea9000001')
#
# @param [ Symbol ] Counter cache name
# @param [ String ] The id of the object that will have its counter incremented.
#
# @since 3.1.0
def increment_counter(counter_name, id)
update_counters(id, counter_name.to_sym => 1)
end
# Decrement the counter name from the entries that match the
# id by one. This method is used on associations callbacks
# when counter_cache is enabled
#
# @example Decrement comments counter
# Post.decrement_counter(:comments_count, '50e0edd97c71c17ea9000001')
#
# @param [ Symbol ] Counter cache name
# @param [ String ] The id of the object that will have its counter decremented.
#
# @since 3.1.0
def decrement_counter(counter_name, id)
update_counters(id, counter_name.to_sym => -1)
end
private
# Add the callbacks responsible for update the counter cache field
#
# @api private
#
# @example Add the touchable.
# Person.add_counter_cache_callbacks(meta)
#
# @param [ Metadata ] metadata The metadata for the relation.
#
# @since 3.1.0
def add_counter_cache_callbacks(meta)
name = meta.name
cache_column = meta.counter_cache_column_name.to_sym
after_create do
if record = __send__(name)
record[cache_column] = (record[cache_column] || 0) + 1
if record.persisted?
record.class.increment_counter(cache_column, record._id)
record.remove_change(cache_column)
end
end
end
before_destroy do
if record = __send__(name)
record[cache_column] = (record[cache_column] || 0) - 1 unless record.frozen?
if record.persisted?
record.class.decrement_counter(cache_column, record._id)
record.remove_change(cache_column)
end
end
end
end
end
end
end
end