Module: MongoMapper::Plugins::CounterCache::ClassMethods

Defined in:
lib/mongo_mapper/plugins/counter_cache.rb

Instance Method Summary collapse

Instance Method Details

#_raise_when_missing_counter_cache_key(klass, field) ⇒ Object



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# File 'lib/mongo_mapper/plugins/counter_cache.rb', line 91

def _raise_when_missing_counter_cache_key(klass, field)
  raise InvalidCounterCacheError, "Missing `key #{field.to_sym.inspect}, Integer, :default => 0' on model #{klass}"
end

#counter_cache(association_name, options = {}) ⇒ Object



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# File 'lib/mongo_mapper/plugins/counter_cache.rb', line 39

def counter_cache(association_name, options = {})
  options.symbolize_keys!

  field = options[:field] ?
    options[:field] :
    "#{self.collection_name.gsub(/.*\./, '')}_count"

  association = associations[association_name]

  if !association
    raise InvalidCounterCacheError, "You must define an association with name `#{association_name}' on model #{self}"
  end

  # make a define-time check to make sure the counter cache field is defined.
  # note: this can only be done in non-polymorphic classes
  # (since we may not know the class on the other side of the association)
  if !association.polymorphic?
    association_class = association.klass
    key_names = association_class.keys.keys

    if !key_names.include?(field.to_s)
      _raise_when_missing_counter_cache_key(association_class, field)
    end
  end

  after_create do
    if obj = self.send(association_name)
      if !obj.respond_to?(field)
        self.class._raise_when_missing_counter_cache_key(obj.class, field)
      end

      obj.increment(field => 1)
      obj.write_attribute(field, obj.read_attribute(field) + 1)
    end

    true
  end

  after_destroy do
    if obj = self.send(association_name)
      if !obj.respond_to?(field)
        self.class._raise_when_missing_counter_cache_key(obj.class, field)
      end

      obj.decrement(field => 1)
      obj.write_attribute(field, obj.read_attribute(field) - 1)
    end

    true
  end
end