ruby on rails - Active Record, count of grandchild association record -


let's i've got:

class town < activerecord::base   has_many :citizens end  class citizen < activerecord::base   belongs_to :town   has_many :cars end  class car < activerecord::base   belongs_to :citizen end

using activerecord, simplest way can count of cars in town?

in models can define through association.

class town < activerecord::base   has_many :citizens   has_many :cars , :through => :citizens end

and query this.

@town.cars.count

or

town.find("town id").cars.count

-

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