Module: Mongoid::Association::Referenced::CounterCache

Extended by:
ActiveSupport::Concern
Included in:
Mongoid::Association
Defined in:
lib/mongoid/association/referenced/counter_cache.rb

Overview

Mixin module included into Mongoid::Document which adds the ability to cache the count of opposite-side documents in referenced n-to-many associations.

Defined Under Namespace

Modules: ClassMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.define_callbacks!(association) ⇒ Class

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Add the callbacks responsible for update the counter cache field.

Examples:

Add the touchable.

Mongoid::Association::Referenced::CounterCache.define_callbacks!(association)

Parameters:

Returns:

  • (Class) —

    The association’s owning class.



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# File 'lib/mongoid/association/referenced/counter_cache.rb', line 99

def self.define_callbacks!(association)
  name = association.name
  cache_column = association.counter_cache_column_name.to_sym

  association.inverse_class.tap do |klass|
    klass.after_update do
      foreign_key = association.foreign_key

      if send("#{foreign_key}_previously_changed?")
        original, current = send("#{foreign_key}_previous_change")

        unless original.nil?
          association.klass.with(persistence_context.for_child(association.klass)) do |_class|
            _class.decrement_counter(cache_column, original)
          end
        end

        if record = __send__(name)
          unless current.nil?
            record[cache_column] = (record[cache_column] || 0) + 1
            record.class.with(record.persistence_context) do |_class|
              _class.increment_counter(cache_column, current) if record.persisted?
            end
          end
        end
      end
    end

    klass.after_create do
      if record = __send__(name)
        record[cache_column] = (record[cache_column] || 0) + 1

        if record.persisted?
          record.class.with(record.persistence_context) do |_class|
            _class.increment_counter(cache_column, record._id)
          end
          record.remove_change(cache_column)
        end
      end
    end

    klass.before_destroy do
      if record = __send__(name)
        record[cache_column] = (record[cache_column] || 0) - 1 unless record.frozen?

        if record.persisted?
          record.class.with(record.persistence_context) do |_class|
            _class.decrement_counter(cache_column, record._id)
          end
          record.remove_change(cache_column)
        end
      end
    end
  end
end

Instance Method Details

#reset_counters(*counters) ⇒ Object

Reset the given counter using the .count() query from the db. This method is useful in case that a counter got corrupted, or a new counter was added to the collection.

Examples:

Reset the given counter cache

post.reset_counters(:comments)

Parameters:

  • *counters (Symbol...) —

    One or more counter caches to reset.



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# File 'lib/mongoid/association/referenced/counter_cache.rb', line 22

def reset_counters(*counters)
  self.class.with(persistence_context) do |_class|
    _class.reset_counters(self, *counters)
  end
end